1
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Weituschat LM, Castro I, Colomar I, Everly C, Postigo PA, Ramos D. Exploring regenerative coupling in phononic crystals for room temperature quantum optomechanics. Sci Rep 2024; 14:12330. [PMID: 38811848 PMCID: PMC11137142 DOI: 10.1038/s41598-024-63199-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Accepted: 05/27/2024] [Indexed: 05/31/2024] Open
Abstract
Quantum technologies play a pivotal role in driving transformative advancements across diverse fields, surpassing classical approaches and empowering us to address complex challenges more effectively; however, the need for ultra-low temperatures limits the use of these technologies to particular fields. This work comes to alleviate this problem. We present a way of phononic bandgap engineering using FEM by which the radiative mechanical energy dissipation of a nanomechanical oscillator can be significantly suppressed through coupling with a complementary oscillating mode of a defect of the surrounding phononic crystal (PnC). Applied to an optomechanically coupled nanobeam resonator in the megahertz regime, we find a mechanical quality factor improvement of up to four orders of magnitude compared to conventional PnC designs. As this method is based on geometrical optimization of the PnC and frequency matching of the resonator and defect mode, it is applicable to a wide range of resonator types and frequency ranges. Taking advantage of the, hereinafter referred to as, "regenerative coupling" in phononic crystals, the presented device is capable of reaching f × Q products exceeding 10E16 Hz with only two rows of PnC shield. Thus, stable quantum states with mechanical decoherence times up to 700 μs at room temperature can be obtained, offering new opportunities for the optimization of mechanical resonator performance and advancing the room temperature quantum field across diverse applications.
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Affiliation(s)
- Lukas M Weituschat
- Optomechanics Lab, Instituto de Ciencia de Materiales de Madrid (ICMM), CSIC, 3, Sor Juana Inés de la Cruz, 28049, Madrid, Spain
| | - Irene Castro
- Optomechanics Lab, Instituto de Ciencia de Materiales de Madrid (ICMM), CSIC, 3, Sor Juana Inés de la Cruz, 28049, Madrid, Spain
| | - Irene Colomar
- Optomechanics Lab, Instituto de Ciencia de Materiales de Madrid (ICMM), CSIC, 3, Sor Juana Inés de la Cruz, 28049, Madrid, Spain
| | - Christer Everly
- The Institute of Optics, University of Rochester, Rochester, NY, 14627, USA
| | - Pablo A Postigo
- The Institute of Optics, University of Rochester, Rochester, NY, 14627, USA
| | - Daniel Ramos
- Optomechanics Lab, Instituto de Ciencia de Materiales de Madrid (ICMM), CSIC, 3, Sor Juana Inés de la Cruz, 28049, Madrid, Spain.
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2
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Liao YQ, Liu YC, Wang YH, Fu PX, Xie Y, Gao S, Wang YX, Liu Z, Jiang SD. Angular-resolved Rabi oscillations of orthorhombic spins in a Co(II) molecular qubit. Phys Chem Chem Phys 2024; 26:14832-14838. [PMID: 38721813 DOI: 10.1039/d4cp01017e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2024]
Abstract
Magnetic molecules are promising candidates for quantum information processing (QIP) due to their tunable electron structures and quantum properties. A high spin Co(II) complex, CoH2dota, is studied for its potential to be used as a quantum bit (qubit) utilizing continuous wave (CW) and pulsed electron paramagnetic resonance (EPR) spectroscopy at low temperature. On the X-band microwave energy scale, the system can be treated as an effective spin 1/2 with a strongly anisotropic g-tensor resulting from the significant spin-orbital coupling. An experimental and theoretical study is conducted to investigate the anisotropic Rabi oscillations of the two magnetically equivalent spin centres with different orientations in a single crystal sample, which aims to verify the relationship between the Rabi frequency and the orientation of the g-tensor. The findings of this study show that an effective quantum manipulation method is developed for orthorhombic spin systems.
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Affiliation(s)
- Yi-Qiu Liao
- Spin-X Institute, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 511442, China.
| | - You-Chao Liu
- Spin-X Institute, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 511442, China.
| | - Yi-Han Wang
- Beijing National Laboratory of Molecular Science, Beijing Key Laboratory of Magnetoelectric Materials and Devices, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Peng-Xiang Fu
- Beijing National Laboratory of Molecular Science, Beijing Key Laboratory of Magnetoelectric Materials and Devices, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Yi Xie
- Spin-X Institute, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 511442, China.
| | - Song Gao
- Spin-X Institute, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 511442, China.
- Beijing National Laboratory of Molecular Science, Beijing Key Laboratory of Magnetoelectric Materials and Devices, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, LIFM, School of Chemistry, IGCME, Sun Yat-Sen University, Guangzhou 510275, China.
| | - Ye-Xin Wang
- Quantum Science Centre of Guangdong-Hong Kong-Macao Greater Bay Area, Shenzhen-Hong Kong International Science and Technology Park, NO. 3 Binglang Road, Futian District, Shenzhen, Guangdong, 518045, China.
| | - Zheng Liu
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, LIFM, School of Chemistry, IGCME, Sun Yat-Sen University, Guangzhou 510275, China.
| | - Shang-Da Jiang
- Spin-X Institute, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 511442, China.
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3
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Chepelianskii AD, Shepelyansky DL. Quantum Synchronization and Entanglement of Dissipative Qubits Coupled to a Resonator. ENTROPY (BASEL, SWITZERLAND) 2024; 26:415. [PMID: 38785664 PMCID: PMC11119807 DOI: 10.3390/e26050415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 04/21/2024] [Accepted: 05/10/2024] [Indexed: 05/25/2024]
Abstract
In a dissipative regime, we study the properties of several qubits coupled to a driven resonator in the framework of a Jaynes-Cummings model. The time evolution and the steady state of the system are numerically analyzed within the Lindblad master equation, with up to several million components. Two semi-analytical approaches, at weak and strong (semiclassical) dissipations, are developed to describe the steady state of this system and determine its validity by comparing it with the Lindblad equation results. We show that the synchronization of several qubits with the driving phase can be obtained due to their coupling to the resonator. We establish the existence of two different qubit synchronization regimes: In the first one, the semiclassical approach describes well the dynamics of qubits and, thus, their quantum features and entanglement are suppressed by dissipation and the synchronization is essentially classical. In the second one, the entangled steady state of a pair of qubits remains synchronized in the presence of dissipation and decoherence, corresponding to the regime non-existent in classical synchronization.
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Affiliation(s)
| | - Dima L. Shepelyansky
- Laboratoire de Physique Théorique, IRSAMC, Université de Toulouse, CNRS, UPS, 31062 Toulouse, France
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4
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Singh H, Kolodrubetz MH, Gopalakrishnan S, Vasseur R. Tunable Superdiffusion in Integrable Spin Chains Using Correlated Initial States. PHYSICAL REVIEW LETTERS 2024; 132:176303. [PMID: 38728724 DOI: 10.1103/physrevlett.132.176303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 02/05/2024] [Accepted: 04/01/2024] [Indexed: 05/12/2024]
Abstract
Although integrable spin chains host only ballistically propagating particles, they can still feature diffusive charge transfer. This diffusive charge transfer originates from quasiparticle charge fluctuations inherited from the initial state's magnetization Gaussian fluctuations. We show that ensembles of initial states with quasi-long-range correlations lead to superdiffusive charge transfer with a tunable dynamical exponent. We substantiate our prediction with numerical simulations and discuss how finite time and finite size effects might cause deviations.
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Affiliation(s)
- Hansveer Singh
- Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Michael H Kolodrubetz
- Department of Physics, The University of Texas at Dallas, Richardson, Texas 75080, USA
| | - Sarang Gopalakrishnan
- Department of Electrical and Computer Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Romain Vasseur
- Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA
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5
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Gutman N, Gorlach A, Tziperman O, Ruimy R, Kaminer I. Universal Control of Symmetric States Using Spin Squeezing. PHYSICAL REVIEW LETTERS 2024; 132:153601. [PMID: 38682988 DOI: 10.1103/physrevlett.132.153601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Accepted: 03/11/2024] [Indexed: 05/01/2024]
Abstract
The manipulation of quantum many-body systems is a crucial goal in quantum science. Entangled quantum states that are symmetric under qubits permutation are of growing interest. Yet, the creation and control of symmetric states has remained a challenge. Here, we introduce a method to universally control symmetric states, proposing a scheme that relies solely on coherent rotations and spin squeezing. We present protocols for the creation of different symmetric states including Schrödinger's cat and Gottesman-Kitaev-Preskill states. The obtained symmetric states can be transferred to traveling photonic states via spontaneous emission, providing a powerful approach for engineering desired quantum photonic states.
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Affiliation(s)
- Nir Gutman
- Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Alexey Gorlach
- Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Offek Tziperman
- Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Ron Ruimy
- Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Ido Kaminer
- Technion-Israel Institute of Technology, Haifa 32000, Israel
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6
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Bertini B, Kos P, Prosen T. Localized Dynamics in the Floquet Quantum East Model. PHYSICAL REVIEW LETTERS 2024; 132:080401. [PMID: 38457727 DOI: 10.1103/physrevlett.132.080401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 01/23/2024] [Indexed: 03/10/2024]
Abstract
We introduce and study the discrete-time version of the quantum East model, an interacting quantum spin chain inspired by simple kinetically constrained models of classical glasses. Previous work has established that its continuous-time counterpart displays a disorder-free localization transition signaled by the appearance of an exponentially large (in the volume) family of nonthermal, localized eigenstates. Here we combine analytical and numerical approaches to show that (i) the transition persists for discrete times, in fact, it is present for any finite value of the time step apart from a zero measure set; (ii) it is directly detected by following the nonequilibrium dynamics of the fully polarized state. Our findings imply that the transition is currently observable in state-of-the-art platforms for digital quantum simulation.
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Affiliation(s)
- Bruno Bertini
- School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, United Kingdom
- Centre for the Mathematics and Theoretical Physics of Quantum Non-Equilibrium Systems, University of Nottingham, Nottingham, NG7 2RD, United Kingdom
| | - Pavel Kos
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, 85748 Garching, Germany
| | - Tomaž Prosen
- Department of Physics, Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia
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7
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Rolczynski BS, Díaz SA, Goldman ER, Medintz IL, Melinger JS. Investigating the dissipation of heat and quantum information from DNA-scaffolded chromophore networks. J Chem Phys 2024; 160:034105. [PMID: 38230810 DOI: 10.1063/5.0181034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 12/15/2023] [Indexed: 01/18/2024] Open
Abstract
Scaffolded molecular networks are important building blocks in biological pigment-protein complexes, and DNA nanotechnology allows analogous systems to be designed and synthesized. System-environment interactions in these systems are responsible for important processes, such as the dissipation of heat and quantum information. This study investigates the role of nanoscale molecular parameters in tuning these vibronic system-environment dynamics. Here, genetic algorithm methods are used to obtain nanoscale parameters for a DNA-scaffolded chromophore network based on comparisons between its calculated and measured optical spectra. These parameters include the positions, orientations, and energy level characteristics within the network. This information is then used to compute the dynamics, including the vibronic population dynamics and system-environment heat currents, using the hierarchical equations of motion. The dissipation of quantum information is identified by the system's transient change in entropy, which is proportional to the heat currents according to the second law of thermodynamics. These results indicate that the dissipation of quantum information is highly dependent on the particular nanoscale characteristics of the molecular network, which is a necessary first step before gleaning the systematic optimization rules. Subsequently, the I-concurrence dynamics are calculated to understand the evolution of the vibronic system's quantum entanglement, which are found to be long-lived compared to these system-bath dissipation processes.
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Affiliation(s)
- Brian S Rolczynski
- Electronics Science and Technology Division, Code 6800, U.S. Naval Research Laboratory, Washington, District of Columbia 20375, USA
| | - Sebastián A Díaz
- Center for Bio/Molecular Science and Engineering, Code 6900, U.S. Naval Research Laboratory, Washington, District of Columbia 20375, USA
| | - Ellen R Goldman
- Center for Bio/Molecular Science and Engineering, Code 6900, U.S. Naval Research Laboratory, Washington, District of Columbia 20375, USA
| | - Igor L Medintz
- Center for Bio/Molecular Science and Engineering, Code 6900, U.S. Naval Research Laboratory, Washington, District of Columbia 20375, USA
| | - Joseph S Melinger
- Electronics Science and Technology Division, Code 6800, U.S. Naval Research Laboratory, Washington, District of Columbia 20375, USA
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8
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Wang L, Ran Q, Ding J. Image Encryption Using Quantum 3D Mobius Scrambling and 3D Hyper-Chaotic Henon Map. ENTROPY (BASEL, SWITZERLAND) 2023; 25:1629. [PMID: 38136509 PMCID: PMC10743145 DOI: 10.3390/e25121629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 11/27/2023] [Accepted: 12/04/2023] [Indexed: 12/24/2023]
Abstract
In encryption technology, image scrambling is a common processing operation. This paper proposes a quantum version of the 3D Mobius scrambling transform based on the QRCI model, which changes not only the position of pixels but also the gray values. The corresponding quantum circuits are devised. Furthermore, an encryption scheme combining the quantum 3D Mobius transform with the 3D hyper-chaotic Henon map is suggested to protect the security of image information. To facilitate subsequent processing, the RGB color image is first represented with QRCI. Then, to achieve the pixel-level permutation effect, the quantum 3D Mobius transform is applied to scramble bit-planes and pixel positions. Ultimately, to increase the diffusion effect, the scrambled image is XORed with a key image created by the 3D hyper-chaotic Henon map to produce the encrypted image. Numerical simulations and result analyses indicate that our designed encryption scheme is secure and reliable. It offers better performance in the aspect of key space, histogram variance, and correlation coefficient than some of the latest algorithms.
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Affiliation(s)
- Ling Wang
- School of Internet, Anhui University, Hefei 230039, China
| | - Qiwen Ran
- National Key Laboratory of Tunable Laser Technology, Harbin Institute of Technology, Harbin 150001, China
| | - Junrong Ding
- National Key Laboratory of Tunable Laser Technology, Harbin Institute of Technology, Harbin 150001, China
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9
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Matarèse BFE, Rusin A, Seymour C, Mothersill C. Quantum Biology and the Potential Role of Entanglement and Tunneling in Non-Targeted Effects of Ionizing Radiation: A Review and Proposed Model. Int J Mol Sci 2023; 24:16464. [PMID: 38003655 PMCID: PMC10671017 DOI: 10.3390/ijms242216464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 11/01/2023] [Accepted: 11/13/2023] [Indexed: 11/26/2023] Open
Abstract
It is well established that cells, tissues, and organisms exposed to low doses of ionizing radiation can induce effects in non-irradiated neighbors (non-targeted effects or NTE), but the mechanisms remain unclear. This is especially true of the initial steps leading to the release of signaling molecules contained in exosomes. Voltage-gated ion channels, photon emissions, and calcium fluxes are all involved but the precise sequence of events is not yet known. We identified what may be a quantum entanglement type of effect and this prompted us to consider whether aspects of quantum biology such as tunneling and entanglement may underlie the initial events leading to NTE. We review the field where it may be relevant to ionizing radiation processes. These include NTE, low-dose hyper-radiosensitivity, hormesis, and the adaptive response. Finally, we present a possible quantum biological-based model for NTE.
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Affiliation(s)
- Bruno F. E. Matarèse
- Department of Haematology, University of Cambridge, Cambridge CB2 1TN, UK;
- Department of Physics, University of Cambridge, Cambridge CB2 1TN, UK
| | - Andrej Rusin
- Department of Biology, McMaster University, Hamilton, ON L8S 4L8, Canada; (A.R.); (C.S.)
| | - Colin Seymour
- Department of Biology, McMaster University, Hamilton, ON L8S 4L8, Canada; (A.R.); (C.S.)
| | - Carmel Mothersill
- Department of Biology, McMaster University, Hamilton, ON L8S 4L8, Canada; (A.R.); (C.S.)
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10
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Salimian S, Tavassoly MK, Ghasemi M. Multistage entanglement swapping using superconducting qubits in the absence and presence of dissipative environment without Bell state measurement. Sci Rep 2023; 13:16342. [PMID: 37770646 PMCID: PMC10539405 DOI: 10.1038/s41598-023-43592-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 09/26/2023] [Indexed: 09/30/2023] Open
Abstract
In recent decades the entangled state generation is of great importance in the quantum information processing and technologies. In this paper, producing the distributed entangled state of superconducting (SC) qubits is considered using an entanglement swapping protocol in three successive stages. The SC qubit pairs [Formula: see text] with [Formula: see text], where each pair of the qubits has been placed on a separate chip, are initially prepared in maximally entangled states. The external magnetic fields on capacitively coupled pairs [Formula: see text] and [Formula: see text] are implemented for modulating the frequency of qubits. Then, the SC qubits [Formula: see text] and [Formula: see text] are converted into entangled states via operating proper measurements instead of Bell state measurement (which is generally a hard task). Finally, the distributed entangled state of target SC qubits [Formula: see text] can be obtained by applying external magnetic fields on qubits [Formula: see text] and via operating suitable measurements. This process is studied in the absence and presence of thermal decoherence effects. The concurrence, as a measure of entanglement between two target qubits, success probability of the distributed entangled states and the corresponding fidelities are evaluated, by which we find that the state of target SC qubits [Formula: see text] is converted to Bell state with maximum entanglement at some moments of time. Under appropriate conditions the maximum of success probability of the obtained states in each stage approaches 1. However, the maxima of concurrence and success probability gradually decrease due to the thermal noise as time goes on. Moreover, compelling amounts of fidelity, success probability and entanglement can be obtained for the achieved entangled states.
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Affiliation(s)
- S Salimian
- Laser and Optics Group, Faculty of Physics, Yazd University, Yazd, Iran
| | - M K Tavassoly
- Laser and Optics Group, Faculty of Physics, Yazd University, Yazd, Iran.
| | - M Ghasemi
- Laser and Optics Group, Faculty of Physics, Yazd University, Yazd, Iran
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11
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Wesdorp JJ, Grünhaupt L, Vaartjes A, Pita-Vidal M, Bargerbos A, Splitthoff LJ, Krogstrup P, van Heck B, de Lange G. Dynamical Polarization of the Fermion Parity in a Nanowire Josephson Junction. PHYSICAL REVIEW LETTERS 2023; 131:117001. [PMID: 37774257 DOI: 10.1103/physrevlett.131.117001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 01/22/2023] [Accepted: 07/14/2023] [Indexed: 10/01/2023]
Abstract
Josephson junctions in InAs nanowires proximitized with an Al shell can host gate-tunable Andreev bound states. Depending on the bound state occupation, the fermion parity of the junction can be even or odd. Coherent control of Andreev bound states has recently been achieved within each parity sector, but it is impeded by incoherent parity switches due to excess quasiparticles in the superconducting environment. Here, we show that we can polarize the fermion parity dynamically using microwave pulses by embedding the junction in a superconducting LC resonator. We demonstrate polarization up to 94%±1% (89%±1%) for the even (odd) parity as verified by single shot parity readout. Finally, we apply this scheme to probe the flux-dependent transition spectrum of the even or odd parity sector selectively, without any postprocessing or heralding.
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Affiliation(s)
- J J Wesdorp
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ, Delft, Netherlands
| | - L Grünhaupt
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ, Delft, Netherlands
| | - A Vaartjes
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ, Delft, Netherlands
| | - M Pita-Vidal
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ, Delft, Netherlands
| | - A Bargerbos
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ, Delft, Netherlands
| | - L J Splitthoff
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ, Delft, Netherlands
| | - P Krogstrup
- NNF Quantum Computing Programme, Niels Bohr Institute, University of Copenhagen, Denmark
| | - B van Heck
- Microsoft Quantum Lab Delft, 2628 CJ, Delft, Netherlands
- Leiden Institute of Physics, Universiteit Leiden, Niels Bohrweg 2, 2333 CA Leiden, Netherlands
- Dipartimento di Fisica, Sapienza Università di Roma, P.le Aldo Moro 2, 00185 Roma, Italy
| | - G de Lange
- Microsoft Quantum Lab Delft, 2628 CJ, Delft, Netherlands
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12
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Schlimgen AW, Guo Y, Head-Marsden K. Characterizing Excited States of a Copper-Based Molecular Qubit Candidate with Correlated Electronic Structure Methods. J Phys Chem A 2023; 127:6764-6770. [PMID: 37531508 DOI: 10.1021/acs.jpca.3c03827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/04/2023]
Abstract
Molecular spins have a variety of potential advantages as qubits for quantum computation, such as tunability and well-understood design pathways through organometallic synthesis. Organometallic and heavy-metal-based molecular spin qubits can also exhibit rich electronic structures due to ligand field interactions and electron correlation. These features make consistent and reliable modeling of these species a considerable challenge for contemporary electronic structure techniques. Here, we elucidate the electronic structure of a Cu(II) complex analogous to a recently proposed room-temperature molecular spin qubit. Using active space methods to describe the electron correlation, we show the nuanced interaction between the metal d orbitals and ligand σ and π orbitals makes these systems challenging to model, both in terms of the delocalized spin density and the excited state ordering. We show that predicting the correct spin delocalization requires special consideration of the Cu d orbitals and that the excited state spectrum for the Cu(III) complex also requires the explicit inclusion of the π orbitals in the active space. These interactions are rather common in molecular spin qubit motifs and may play an important role in spin-decoherence processes. Our results may lend insight into future studies of the orbital interactions and electron delocalization of similar complexes.
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Affiliation(s)
- Anthony W Schlimgen
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 61630, United States
| | - Yangyang Guo
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 61630, United States
| | - Kade Head-Marsden
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 61630, United States
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13
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Wang SP, Ridolfo A, Li T, Savasta S, Nori F, Nakamura Y, You JQ. Probing the symmetry breaking of a light-matter system by an ancillary qubit. Nat Commun 2023; 14:4397. [PMID: 37474535 PMCID: PMC10359332 DOI: 10.1038/s41467-023-40097-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 07/11/2023] [Indexed: 07/22/2023] Open
Abstract
Hybrid quantum systems in the ultrastrong, and even more in the deep-strong, coupling regimes can exhibit exotic physical phenomena and promise new applications in quantum technologies. In these nonperturbative regimes, a qubit-resonator system has an entangled quantum vacuum with a nonzero average photon number in the resonator, where the photons are virtual and cannot be directly detected. The vacuum field, however, is able to induce the symmetry breaking of a dispersively coupled probe qubit. We experimentally observe the parity symmetry breaking of an ancillary Xmon artificial atom induced by the field of a lumped-element superconducting resonator deep-strongly coupled with a flux qubit. This result opens a way to experimentally explore the novel quantum-vacuum effects emerging in the deep-strong coupling regime.
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Affiliation(s)
- Shuai-Peng Wang
- Quantum Physics and Quantum Information Division, Beijing Computational Science Research Center, Beijing, 100193, China
- Interdisciplinary Center of Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, and Zhejiang Province Key Laboratory of Quantum Technology and Device, School of Physics, Zhejiang University, Hangzhou, 310027, China
| | - Alessandro Ridolfo
- Dipartimento di Fisica e Astronomia, Università di Catania, 95123, Catania, Italy
| | - Tiefu Li
- School of Integrated Circuits, and Frontier Science Center for Quantum Information, Tsinghua University, Beijing, 100084, China.
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China.
| | - Salvatore Savasta
- Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra, Università di Messina, I-98166, Messina, Italy.
| | - Franco Nori
- Theoretical Quantum Physics Laboratory, Cluster for Pioneering Research, RIKEN, Wako, Saitama, 351-0198, Japan
- Physics Department, The University of Michigan, Ann Arbor, MI, 48109-1040, USA
- RIKEN Center for Quantum Computing (RQC), Wako, Saitama, 351-0198, Japan
| | - Y Nakamura
- RIKEN Center for Quantum Computing (RQC), Wako, Saitama, 351-0198, Japan
- Department of Applied Physics, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - J Q You
- Interdisciplinary Center of Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, and Zhejiang Province Key Laboratory of Quantum Technology and Device, School of Physics, Zhejiang University, Hangzhou, 310027, China.
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14
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Hassani F, Peruzzo M, Kapoor LN, Trioni A, Zemlicka M, Fink JM. Inductively shunted transmons exhibit noise insensitive plasmon states and a fluxon decay exceeding 3 hours. Nat Commun 2023; 14:3968. [PMID: 37407570 DOI: 10.1038/s41467-023-39656-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 06/22/2023] [Indexed: 07/07/2023] Open
Abstract
Currently available quantum processors are dominated by noise, which severely limits their applicability and motivates the search for new physical qubit encodings. In this work, we introduce the inductively shunted transmon, a weakly flux-tunable superconducting qubit that offers charge offset protection for all levels and a 20-fold reduction in flux dispersion compared to the state-of-the-art resulting in a constant coherence over a full flux quantum. The parabolic confinement provided by the inductive shunt as well as the linearity of the geometric superinductor facilitates a high-power readout that resolves quantum jumps with a fidelity and QND-ness of >90% and without the need for a Josephson parametric amplifier. Moreover, the device reveals quantum tunneling physics between the two prepared fluxon ground states with a measured average decay time of up to 3.5 h. In the future, fast time-domain control of the transition matrix elements could offer a new path forward to also achieve full qubit control in the decay-protected fluxon basis.
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Affiliation(s)
- F Hassani
- Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria.
| | - M Peruzzo
- Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria
| | - L N Kapoor
- Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria
| | - A Trioni
- Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria
| | - M Zemlicka
- Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria
| | - J M Fink
- Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria.
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15
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Vernier E, Bertini B, Giudici G, Piroli L. Integrable Digital Quantum Simulation: Generalized Gibbs Ensembles and Trotter Transitions. PHYSICAL REVIEW LETTERS 2023; 130:260401. [PMID: 37450812 DOI: 10.1103/physrevlett.130.260401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 04/18/2023] [Accepted: 06/05/2023] [Indexed: 07/18/2023]
Abstract
The Trotter-Suzuki decomposition is a promising avenue for digital quantum simulation (DQS), approximating continuous-time dynamics by discrete Trotter steps of duration τ. Recent work suggested that DQS is typically characterized by a sharp Trotter transition: when τ is increased beyond a threshold value, approximation errors become uncontrolled at large times due to the onset of quantum chaos. Here, we contrast this picture with the case of integrable DQS. We focus on a simple quench from a spin-wave state in the prototypical XXZ Heisenberg spin chain, and study its integrable Trotterized evolution as a function of τ. Because of its exact local conservation laws, the system does not heat up to infinite temperature and the late-time properties of the dynamics are captured by a discrete generalized Gibbs ensemble (dGGE). By means of exact calculations we find that, for small τ, the dGGE depends analytically on the Trotter step, implying that discretization errors remain bounded even at infinite times. Conversely, the dGGE changes abruptly at a threshold value τ_{th}, signaling a novel type of Trotter transition. We show that the latter can be detected locally, as it is associated with the appearance of a nonzero staggered magnetization with a subtle dependence on τ. We highlight the differences between continuous and discrete GGEs, suggesting the latter as novel interesting nonequilibrium states exclusive to digital platforms.
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Affiliation(s)
- Eric Vernier
- CNRS and Université Paris Cité, Laboratoire de Probabilités, Statistique et Modélisation, F-75013 Paris, France
| | - Bruno Bertini
- School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, United Kingdom
- Centre for the Mathematics and Theoretical Physics of Quantum Non-Equilibrium Systems, University of Nottingham, Nottingham, NG7 2RD, United Kingdom
| | - Giuliano Giudici
- Arnold Sommerfeld Center for Theoretical Physics, University of Munich, Theresienstr. 37, 80333 München, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstraße 4, 80799 München, Germany
| | - Lorenzo Piroli
- Philippe Meyer Institute, Physics Department, École Normale Supérieure (ENS), Université PSL, 24 rue Lhomond, F-75231 Paris, France
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16
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de Paula MVS, Sinesio WWT, Dodonov AV. Ancilla-Assisted Generation of Photons from Vacuum via Time-Modulation of Extracavity Qubit. ENTROPY (BASEL, SWITZERLAND) 2023; 25:901. [PMID: 37372245 DOI: 10.3390/e25060901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 05/14/2023] [Accepted: 05/22/2023] [Indexed: 06/29/2023]
Abstract
We propose a scheme for the generation of photons from a vacuum via time-modulation of a quantum system indirectly coupled to the cavity field through some ancilla quantum subsystem. We consider the simplest case when the modulation is applied to an artificial two-level atom (we call 't-qubit', that can be located even outside the cavity), while the ancilla is a stationary qubit coupled via the dipole interaction both to the cavity and t-qubit. We find that tripartite entangled states with a small number of photons can be generated from the system ground state under resonant modulations, even when the t-qubit is far detuned from both the ancilla and the cavity, provided its bare and modulation frequencies are properly adjusted. We attest our approximate analytic results by numeric simulations and show that photon generation from vacuum persists in the presence of common dissipation mechanisms.
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Affiliation(s)
- Marcos V S de Paula
- Institute of Physics, University of Brasilia, Caixa Postal 04455, Brasilia 70910-900, DF, Brazil
| | - William W T Sinesio
- Institute of Physics, University of Brasilia, Caixa Postal 04455, Brasilia 70910-900, DF, Brazil
| | - Alexandre V Dodonov
- Institute of Physics, University of Brasilia, Caixa Postal 04455, Brasilia 70910-900, DF, Brazil
- International Center of Physics, Institute of Physics, University of Brasilia, Brasilia 70910-900, DF, Brazil
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17
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De Filippis G, de Candia A, Di Bello G, Perroni CA, Cangemi LM, Nocera A, Sassetti M, Fazio R, Cataudella V. Signatures of Dissipation Driven Quantum Phase Transition in Rabi Model. PHYSICAL REVIEW LETTERS 2023; 130:210404. [PMID: 37295090 DOI: 10.1103/physrevlett.130.210404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 04/13/2023] [Indexed: 06/12/2023]
Abstract
By using the worldline Monte Carlo technique, matrix product state, and a variational approach à la Feynman, we investigate the equilibrium properties and relaxation features of the dissipative quantum Rabi model, where a two level system is coupled to a linear harmonic oscillator embedded in a viscous fluid. We show that, in the Ohmic regime, a Beretzinski-Kosterlitz-Thouless quantum phase transition occurs by varying the coupling strength between the two level system and the oscillator. This is a nonperturbative result, occurring even for extremely low dissipation magnitude. By using state-of-the-art theoretical methods, we unveil the features of the relaxation towards the thermodynamic equilibrium, pointing out the signatures of quantum phase transition both in the time and frequency domains. We prove that, for low and moderate values of the dissipation, the quantum phase transition occurs in the deep strong coupling regime. We propose to realize this model by coupling a flux qubit and a damped LC oscillator.
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Affiliation(s)
- G De Filippis
- SPIN-CNR and Dip. di Fisica E. Pancini-Università di Napoli Federico II-I-80126 Napoli, Italy
- INFN, Sezione di Napoli-Complesso Universitario di Monte S. Angelo-I-80126 Napoli, Italy
| | - A de Candia
- SPIN-CNR and Dip. di Fisica E. Pancini-Università di Napoli Federico II-I-80126 Napoli, Italy
- INFN, Sezione di Napoli-Complesso Universitario di Monte S. Angelo-I-80126 Napoli, Italy
| | - G Di Bello
- Dipartimento di Fisica Ettore Pancini-Università di Napoli Federico II-I-80126 Napoli, Italy
| | - C A Perroni
- SPIN-CNR and Dip. di Fisica E. Pancini-Università di Napoli Federico II-I-80126 Napoli, Italy
| | - L M Cangemi
- Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900, Israel
| | - A Nocera
- Department of Physics and Astronomy and Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia, Canada, V6T 1Z1
| | - M Sassetti
- Dipartimento di Fisica, Università di Genova, I-16146 Genova, Italy
- SPIN-CNR, I-16146 Genova, Italy
| | - R Fazio
- SPIN-CNR and Dip. di Fisica E. Pancini-Università di Napoli Federico II-I-80126 Napoli, Italy
- ICTP, Strada Costiera 11, I-34151 Trieste, Italy
- NEST, Istituto Nanoscienze-CNR, I-56126 Pisa, Italy
| | - V Cataudella
- SPIN-CNR and Dip. di Fisica E. Pancini-Università di Napoli Federico II-I-80126 Napoli, Italy
- INFN, Sezione di Napoli-Complesso Universitario di Monte S. Angelo-I-80126 Napoli, Italy
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18
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Crescente A, Ferraro D, Carrega M, Sassetti M. Analytically Solvable Model for Qubit-Mediated Energy Transfer between Quantum Batteries. ENTROPY (BASEL, SWITZERLAND) 2023; 25:e25050758. [PMID: 37238512 DOI: 10.3390/e25050758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 05/03/2023] [Accepted: 05/04/2023] [Indexed: 05/28/2023]
Abstract
The coherent energy transfer between two identical two-level systems is investigated. Here, the first quantum system plays the role of a charger, while the second can be seen as a quantum battery. Firstly, a direct energy transfer between the two objects is considered and then compared to a transfer mediated by an additional intermediate two-level system. In this latter case, it is possible to distinguish between a two-step process, where the energy is firstly transferred from the charger to the mediator and only after from the mediator to the battery, and a single-step in which the two transfers occurs simultaneously. The differences between these configurations are discussed in the framework of an analytically solvable model completing what recently discussed in literature.
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Affiliation(s)
- Alba Crescente
- Dipartimento di Fisica, Università di Genova, Via Dodecaneso 33, 16146 Genova, Italy
- CNR-SPIN, Via Dodecaneso 33, 16146 Genova, Italy
| | - Dario Ferraro
- Dipartimento di Fisica, Università di Genova, Via Dodecaneso 33, 16146 Genova, Italy
- CNR-SPIN, Via Dodecaneso 33, 16146 Genova, Italy
| | | | - Maura Sassetti
- Dipartimento di Fisica, Università di Genova, Via Dodecaneso 33, 16146 Genova, Italy
- CNR-SPIN, Via Dodecaneso 33, 16146 Genova, Italy
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19
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Belousov Y, Chernousov I, Man'ko V. Pseudo-Qutrit Formed by Two Interacting Identical Spins (s = 1/2) in a Variable External Magnetic Field. ENTROPY (BASEL, SWITZERLAND) 2023; 25:e25050716. [PMID: 37238471 DOI: 10.3390/e25050716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 04/15/2023] [Accepted: 04/23/2023] [Indexed: 05/28/2023]
Abstract
An analytical solution is obtained for the problem of two interacting, identical but separated spin 1/2 particles in a time-dependent external magnetic field, in a general case. The solution involves isolating the pseudo-qutrit subsystem from a two-qubit system. It is shown that the quantum dynamics of a pseudo-qutrit system with a magnetic dipole-dipole interaction can be described clearly and accurately in an adiabatic representation, using a time-dependent basis set. The transition probabilities between the energy levels for an adiabatically varying magnetic field, which follows the Landau-Majorana-Stuckelberg-Zener (LMSZ) model within a short time interval, are illustrated in the appropriate graphs. It is shown that for close energy levels and entangled states, the transition probabilities are not small and strongly depend on the time. These results provide insight into the degree of entanglement of two spins (qubits) over time. Furthermore, the results are applicable to more complex systems with a time-dependent Hamiltonian.
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Affiliation(s)
- Yury Belousov
- Terra Quantum AG, St. Gallerstrasse 16A, 9400 Rorschach, Switzerland
| | - Igor Chernousov
- Moscow Institute of Physics and Technology, Institutskiy Per. 9, Moscow Distr., Dolgoprudny 141701, Russia
| | - Vladimir Man'ko
- Lebedev Physical Institute, Leninskii Prospect 53, Moscow 119991, Russia
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20
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Ahmed S, Quijandría F, Kockum AF. Gradient-Descent Quantum Process Tomography by Learning Kraus Operators. PHYSICAL REVIEW LETTERS 2023; 130:150402. [PMID: 37115870 DOI: 10.1103/physrevlett.130.150402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 02/17/2023] [Accepted: 03/16/2023] [Indexed: 06/19/2023]
Abstract
We perform quantum process tomography (QPT) for both discrete- and continuous-variable quantum systems by learning a process representation using Kraus operators. The Kraus form ensures that the reconstructed process is completely positive. To make the process trace preserving, we use a constrained gradient-descent (GD) approach on the so-called Stiefel manifold during optimization to obtain the Kraus operators. Our ansatz uses a few Kraus operators to avoid direct estimation of large process matrices, e.g., the Choi matrix, for low-rank quantum processes. The GD-QPT matches the performance of both compressed-sensing (CS) and projected least-squares (PLS) QPT in benchmarks with two-qubit random processes, but shines by combining the best features of these two methods. Similar to CS (but unlike PLS), GD-QPT can reconstruct a process from just a small number of random measurements, and similar to PLS (but unlike CS) it also works for larger system sizes, up to at least five qubits. We envisage that the data-driven approach of GD-QPT can become a practical tool that greatly reduces the cost and computational effort for QPT in intermediate-scale quantum systems.
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Affiliation(s)
- Shahnawaz Ahmed
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Fernando Quijandría
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
- Quantum Machines Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa 904-0495, Japan
| | - Anton Frisk Kockum
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
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21
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Lock EH, Lee J, Choi DS, Bedford RG, Karna SP, Roy AK. Materials Innovations for Quantum Technology Acceleration: A Perspective. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023:e2201064. [PMID: 37021584 DOI: 10.1002/adma.202201064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 01/16/2023] [Indexed: 06/19/2023]
Abstract
A broad perspective of quantum technology state of the art is provided and critical stumbling blocks for quantum technology development are identified. Innovations in demonstrating and understanding electron entanglement phenomena using bulk and low-dimensional materials and structures are summarized. Correlated photon-pair generation via processes such as nonlinear optics is discussed. Application of qubits to current and future high-impact quantum technology development is presented. Approaches for realizing unique qubit features for large-scale encrypted communication, sensing, computing, and other technologies are still evolving; thus, materials innovation is crucially important. A perspective on materials modeling approaches for quantum technology acceleration that incorporate physics-based AI/ML, integrated with quantum metrology is discussed.
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Affiliation(s)
- Evgeniya H Lock
- Materials Science and Technology Division, U. S. Naval Research Laboratory, Washington, DC, 20375, USA
| | - Jonghoon Lee
- Air Force Research Laboratory, Materials and Manufacturing Directorate, AFRL/RXAN, 2179 12th St, WPAFB, OH, 45433, USA
- ARCTOS Technology Solutions, 1270 N Fairfield Rd, Beavercreek, OH, 45432, USA
| | - Daniel S Choi
- DEVCOM Army Research Laboratory, Weapons and Materials Research Directorate, FCDD-RLW, Aberdeen Proving Ground, Beavercreek, MD, 21015, USA
| | - Robert G Bedford
- Air Force Research Laboratory, Materials and Manufacturing Directorate, AFRL/RXAN, 2179 12th St, WPAFB, OH, 45433, USA
| | - Shashi P Karna
- DEVCOM Army Research Laboratory, Weapons and Materials Research Directorate, FCDD-RLW, Aberdeen Proving Ground, Beavercreek, MD, 21015, USA
| | - Ajit K Roy
- Air Force Research Laboratory, Materials and Manufacturing Directorate, AFRL/RXAN, 2179 12th St, WPAFB, OH, 45433, USA
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22
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Xing FF, Qin LG, Tian LJ, Wu XY, Huang JH. Optomechanically-induced nonreciprocal conversion between microwave and optical photons. OPTICS EXPRESS 2023; 31:7120-7133. [PMID: 36859849 DOI: 10.1364/oe.480597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 01/24/2023] [Indexed: 06/18/2023]
Abstract
We theoretically propose a scheme of the nonreciprocal conversion device between photons of two arbitrary frequencies in a hybrid cavity optomechanical system, where two optical cavities and two microwave cavities are coupled to two different mechanical resonators via radiation pressure. Two mechanical resonators are coupled together via the Coulomb interaction. We study the nonreciprocal conversions between both the same and different types of frequency photons. The device is based on multichannel quantum interference to break the time-reversal symmetry. Our results show the perfect nonreciprocity conditions. By adjusting the Coulomb interaction and the phase differences, we find that the nonreciprocity can be modulated and even transformed into reciprocity. These results provide new insight into the design of nonreciprocal devices, including isolators, circulators, and routers in quantum information processing and quantum networks.
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23
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Arrachea L. Energy dynamics, heat production and heat-work conversion with qubits: toward the development of quantum machines. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2023; 86:036501. [PMID: 36603220 DOI: 10.1088/1361-6633/acb06b] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 01/05/2023] [Indexed: 06/17/2023]
Abstract
We present an overview of recent advances in the study of energy dynamics and mechanisms for energy conversion in qubit systems with special focus on realizations in superconducting quantum circuits. We briefly introduce the relevant theoretical framework to analyze heat generation, energy transport and energy conversion in these systems with and without time-dependent driving considering the effect of equilibrium and non-equilibrium environments. We analyze specific problems and mechanisms under current investigation in the context of qubit systems. These include the problem of energy dissipation and possible routes for its control, energy pumping between driving sources and heat pumping between reservoirs, implementation of thermal machines and mechanisms for energy storage. We highlight the underlying fundamental phenomena related to geometrical and topological properties, as well as many-body correlations. We also present an overview of recent experimental activity in this field.
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Affiliation(s)
- Liliana Arrachea
- Escuela de Ciencia y Tecnología and ICIFI, Universidad de San Martín, Av. 25 de Mayo y Francia, 1650 Buenos Aires, Argentina
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24
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Mozgunov E, Lidar DA. Quantum adiabatic theorem for unbounded Hamiltonians with a cutoff and its application to superconducting circuits. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2023; 381:20210407. [PMID: 36463925 PMCID: PMC9719797 DOI: 10.1098/rsta.2021.0407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 07/18/2022] [Indexed: 06/17/2023]
Abstract
We present a new quantum adiabatic theorem that allows one to rigorously bound the adiabatic timescale for a variety of systems, including those described by originally unbounded Hamiltonians that are made finite-dimensional by a cutoff. Our bound is geared towards the qubit approximation of superconducting circuits and presents a sufficient condition for remaining within the [Formula: see text]-dimensional qubit subspace of a circuit model of [Formula: see text] qubits. The novelty of this adiabatic theorem is that, unlike previous rigorous results, it does not contain [Formula: see text] as a factor in the adiabatic timescale, and it allows one to obtain an expression for the adiabatic timescale independent of the cutoff of the infinite-dimensional Hilbert space of the circuit Hamiltonian. As an application, we present an explicit dependence of this timescale on circuit parameters for a superconducting flux qubit and demonstrate that leakage out of the qubit subspace is inevitable as the tunnelling barrier is raised towards the end of a quantum anneal. We also discuss a method of obtaining a [Formula: see text] effective Hamiltonian that best approximates the true dynamics induced by slowly changing circuit control parameters. This article is part of the theme issue 'Quantum annealing and computation: challenges and perspectives'.
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Affiliation(s)
- Evgeny Mozgunov
- Center for Quantum Information Science and Technology, University of Southern California, Los Angeles, CA 90089, USA
| | - Daniel A. Lidar
- Center for Quantum Information Science and Technology, University of Southern California, Los Angeles, CA 90089, USA
- Department of Electrical and Computer Engineering, University of Southern California, Los Angeles, CA 90089, USA
- Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089, USA
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA
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25
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Murthy AA, Masih Das P, Ribet SM, Kopas C, Lee J, Reagor MJ, Zhou L, Kramer MJ, Hersam MC, Checchin M, Grassellino A, Reis RD, Dravid VP, Romanenko A. Developing a Chemical and Structural Understanding of the Surface Oxide in a Niobium Superconducting Qubit. ACS NANO 2022; 16:17257-17262. [PMID: 36153944 DOI: 10.1021/acsnano.2c07913] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Superconducting thin films of niobium have been extensively employed in transmon qubit architectures. Although these architectures have demonstrated improvements in recent years, further improvements in performance through materials engineering will aid in large-scale deployment. Here, we use information retrieved from secondary ion mass spectrometry and electron microscopy to conduct a detailed assessment of the surface oxide that forms in ambient conditions for transmon test qubit devices patterned from a niobium film. We observe that this oxide exhibits a varying stoichiometry with NbO and NbO2 found closer to the niobium film/oxide interface and Nb2O5 found closer to the surface. In terms of structural analysis, we find that the Nb2O5 region is semicrystalline in nature and exhibits randomly oriented grains on the order of 1-3 nm corresponding to monoclinic N-Nb2O5 that are dispersed throughout an amorphous matrix. Using fluctuation electron microscopy, we are able to map the relative crystallinity in the Nb2O5 region with nanometer spatial resolution. Through this correlative method, we observe that the highly disordered regions are more likely to contain oxygen vacancies and exhibit weaker bonds between the niobium and oxygen atoms. Based on these findings, we expect that oxygen vacancies likely serve as a decoherence mechanism in quantum systems.
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Affiliation(s)
- Akshay A Murthy
- Superconducting Quantum Materials and Systems Division, Fermi National Accelerator Laboratory (FNAL), Batavia, Illinois 60510, United States
| | - Paul Masih Das
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Stephanie M Ribet
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
- International Institute of Nanotechnology, Northwestern University, Evanston, Illinois 60208, United States
| | - Cameron Kopas
- Rigetti Computing, Berkeley, California 94710, United States
| | - Jaeyel Lee
- Superconducting Quantum Materials and Systems Division, Fermi National Accelerator Laboratory (FNAL), Batavia, Illinois 60510, United States
| | | | - Lin Zhou
- Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, United States
| | - Matthew J Kramer
- Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, United States
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Mattia Checchin
- Superconducting Quantum Materials and Systems Division, Fermi National Accelerator Laboratory (FNAL), Batavia, Illinois 60510, United States
| | - Anna Grassellino
- Superconducting Quantum Materials and Systems Division, Fermi National Accelerator Laboratory (FNAL), Batavia, Illinois 60510, United States
| | - Roberto Dos Reis
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
- The NUANCE Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Vinayak P Dravid
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
- International Institute of Nanotechnology, Northwestern University, Evanston, Illinois 60208, United States
- The NUANCE Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Alexander Romanenko
- Superconducting Quantum Materials and Systems Division, Fermi National Accelerator Laboratory (FNAL), Batavia, Illinois 60510, United States
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26
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Abad T, Fernández-Pendás J, Frisk Kockum A, Johansson G. Universal Fidelity Reduction of Quantum Operations from Weak Dissipation. PHYSICAL REVIEW LETTERS 2022; 129:150504. [PMID: 36269966 DOI: 10.1103/physrevlett.129.150504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 09/19/2022] [Indexed: 06/16/2023]
Abstract
Quantum information processing is in real systems often limited by dissipation, stemming from remaining uncontrolled interaction with microscopic degrees of freedom. Given recent experimental progress, we consider weak dissipation, resulting in a small error probability per operation. Here, we find a simple formula for the fidelity reduction of any desired quantum operation, where the ideal evolution is confined to the computational subspace. Interestingly, this reduction is independent of the specific operation; it depends only on the operation time and the dissipation. Using our formula, we investigate the situation where dissipation in different parts of the system has correlations, which is detrimental for the successful application of quantum error correction. Surprisingly, we find that a large class of correlations gives the same fidelity reduction as uncorrelated dissipation of similar strength.
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Affiliation(s)
- Tahereh Abad
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Jorge Fernández-Pendás
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Anton Frisk Kockum
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Göran Johansson
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
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27
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Tang S, Yang C, Li D, Shao X. Implementation of Quantum Algorithms via Fast Three-Rydberg-Atom CCZ Gates. ENTROPY (BASEL, SWITZERLAND) 2022; 24:1371. [PMID: 37420391 DOI: 10.3390/e24101371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 09/20/2022] [Accepted: 09/21/2022] [Indexed: 07/09/2023]
Abstract
Multiqubit CCZ gates form one of the building blocks of quantum algorithms and have been involved in achieving many theoretical and experimental triumphs. Designing a simple and efficient multiqubit gate for quantum algorithms is still by no means trivial as the number of qubits increases. Here, by virtue of the Rydberg blockade effect, we propose a scheme to rapidly implement a three-Rydberg-atom CCZ gate via a single Rydberg pulse, and successfully apply the gate to realize the three-qubit refined Deutsch-Jozsa algorithm and three-qubit Grover search. The logical states of the three-qubit gate are encoded to the same ground states to avoid an adverse effect of the atomic spontaneous emission. Furthermore, there is no requirement for individual addressing of atoms in our protocol.
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Affiliation(s)
- Shiqing Tang
- College of Physics and Electronic Engineering, Hengyang Normal University, Hengyang 421002, China
| | - Chong Yang
- College of Physics Science and Technology, Shenyang Normal University, Shenyang 110034, China
| | - Dongxiao Li
- College of Physics Science and Technology, Shenyang Normal University, Shenyang 110034, China
| | - Xiaoqiang Shao
- Center for Quantum Sciences and School of Physics, Northeast Normal University, Changchun 130024, China
- Center for Advanced Optoelectronic Functional Materials Research, and Key Laboratory for UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024, China
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28
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Sauza-de la Vega A, Pandharkar R, Stroscio GD, Sarkar A, Truhlar DG, Gagliardi L. Multiconfiguration Pair-Density Functional Theory for Chromium(IV) Molecular Qubits. JACS AU 2022; 2:2029-2037. [PMID: 36186551 PMCID: PMC9516709 DOI: 10.1021/jacsau.2c00306] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 08/19/2022] [Accepted: 08/19/2022] [Indexed: 05/30/2023]
Abstract
Pseudotetrahedral organometallic complexes containing chromium(IV) and aryl ligands have been experimentally identified as promising molecular qubit candidates. Here we present a computational protocol based on multiconfiguration pair-density functional theory for computing singlet-triplet gaps and zero-field splitting (ZFS) parameters in Cr(IV) aryl complexes. We find that two multireference methods, multistate complete active space second-order perturbation theory (MS-CASPT2) and hybrid multistate pair-density functional theory (HMS-PDFT), perform better than Kohn-Sham density functional theory for singlet-triplet gaps. Despite the very small values of the ZFS parameters, both multireference methods performed qualitatively well. MS-CASPT2 and HMS-PDFT performed particularly well for predicting the trend in the ratio of the rhombic and axial ZFS parameters, |E/D|. We have also investigated the dependence and sensitivity of the calculated ZFS parameters on the active space and the molecular geometry. The methodologies outlined here can guide future prediction of ZFS parameters in molecular qubit candidates.
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Affiliation(s)
- Arturo Sauza-de la Vega
- Department
of Chemistry, Pritzker School of Molecular Engineering, James Franck
Institute, Chicago Center for Theoretical Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - Riddhish Pandharkar
- Department
of Chemistry, Pritzker School of Molecular Engineering, James Franck
Institute, Chicago Center for Theoretical Chemistry, University of Chicago, Chicago, Illinois 60637, United States
- Argonne
National Laboratory, Lemont, Illinois 60439, United States
| | - Gautam D. Stroscio
- Department
of Chemistry, Pritzker School of Molecular Engineering, James Franck
Institute, Chicago Center for Theoretical Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - Arup Sarkar
- Department
of Chemistry, Pritzker School of Molecular Engineering, James Franck
Institute, Chicago Center for Theoretical Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - Donald G. Truhlar
- Department
of Chemistry, Chemical Theory Center, and Minnesota Supercomputing
Institute, University of Minnesota, Minneapolis, Minnesota 55455−0431, United States
| | - Laura Gagliardi
- Department
of Chemistry, Pritzker School of Molecular Engineering, James Franck
Institute, Chicago Center for Theoretical Chemistry, University of Chicago, Chicago, Illinois 60637, United States
- Argonne
National Laboratory, Lemont, Illinois 60439, United States
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29
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Yang S, Xu JB. Density-wave-ordered phases of Rydberg atoms on a honeycomb lattice. Phys Rev E 2022; 106:034121. [PMID: 36266797 DOI: 10.1103/physreve.106.034121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 08/30/2022] [Indexed: 06/16/2023]
Abstract
Rydberg atom arrays have recently emerged to be a promising platform for the exploration of exotic quantum phases of matter and quantum phenomena. In this work, we map out the ground-state phase diagram of Rydberg atoms on a honeycomb lattice as a function of the Rydberg blockade radius and the laser detuning by performing large-scale finite-size density matrix renormalization group simulations. Apart from a featureless disordered phase, we find five other intricate long-range density-wave-ordered phases within a relatively wide parameter space. The properties of these quantum phases are analyzed by calculating their Rydberg excitation profiles and static structure factors. In addition, a continuous quantum phase transition belonging to the (2+1)-dimensional Ising universality class is explored by a standard finite-size scaling analysis. Our work implies some different physics, such as the possible nontrivial quantum phase transitions and a highly degenerate string ordered phase, that a honeycomb geometry could bring to the Rydberg system and serves as a numerical guide for possible real experiments.
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Affiliation(s)
- Sheng Yang
- Zhejiang Institute of Modern Physics and Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - Jing-Bo Xu
- Zhejiang Institute of Modern Physics and Department of Physics, Zhejiang University, Hangzhou 310027, China
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30
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Qiao L, Gong J. Coherent Control of Collective Spontaneous Emission through Self-Interference. PHYSICAL REVIEW LETTERS 2022; 129:093602. [PMID: 36083648 DOI: 10.1103/physrevlett.129.093602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 08/01/2022] [Indexed: 06/15/2023]
Abstract
As one of the central topics in quantum optics, collective spontaneous emission such as superradiance has been realized in a variety of systems. This Letter proposes an innovative scheme to coherently control collective emission rates via a self-interference mechanism in a nonlinear waveguide setting. The self-interference is made possible by photon backward scattering incurred by quantum scatterers in a waveguide working as quantum switches. Whether the interference is constructive or destructive is found to depend strongly on the distance between the scatterers and the emitters. The interference between two propagation pathways of the same photon leads to controllable superradiance and subradiance, with their collective decay rates much enhanced or suppressed (also leading to hyperradiance or population trapping). Furthermore, the self-interference mechanism is manifested by an abrupt change in the emission rates in real time. An experimental setup based on superconducting transmission line resonators and transmon qubits is further proposed to realize controllable collective emission rates.
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Affiliation(s)
- Lei Qiao
- Department of Physics, National University of Singapore, Singapore 117551, Singapore
| | - Jiangbin Gong
- Department of Physics, National University of Singapore, Singapore 117551, Singapore
- Center for Quantum Technologies, National University of Singapore, Singapore 117543, Singapore
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31
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Acceleration and deceleration of quantum dynamics based on inter-trajectory travel with fast-forward scaling theory. Sci Rep 2022; 12:10744. [PMID: 35750790 PMCID: PMC9232509 DOI: 10.1038/s41598-022-14973-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Accepted: 06/15/2022] [Indexed: 11/11/2022] Open
Abstract
Quantum information processing requires fast manipulations of quantum systems in order to overcome dissipative effects. We propose a method to accelerate quantum dynamics and obtain a target state in a shorter time relative to unmodified dynamics, and apply the theory to a system consisting of two linearly coupled qubits. We extend the technique to accelerate quantum adiabatic evolution in order to rapidly generate a desired target state, thereby realizing a shortcut to adiabaticity. Further, we address experimental limitations to the rate of change of control parameters for quantum devices which often limit one’s ability to generate a desired target state with high fidelity. We show that an initial state following decelerated dynamics can reach a target state while varying control parameters more slowly, enabling more experimentally feasible driving schemes.
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32
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Müller MM, Said RS, Jelezko F, Calarco T, Montangero S. One decade of quantum optimal control in the chopped random basis. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2022; 85:076001. [PMID: 35605567 DOI: 10.1088/1361-6633/ac723c] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 05/23/2022] [Indexed: 06/15/2023]
Abstract
The chopped random basis (CRAB) ansatz for quantum optimal control has been proven to be a versatile tool to enable quantum technology applications such as quantum computing, quantum simulation, quantum sensing, and quantum communication. Its capability to encompass experimental constraints-while maintaining an access to the usually trap-free control landscape-and to switch from open-loop to closed-loop optimization (including with remote access-or RedCRAB) is contributing to the development of quantum technology on many different physical platforms. In this review article we present the development, the theoretical basis and the toolbox for this optimization algorithm, as well as an overview of the broad range of different theoretical and experimental applications that exploit this powerful technique.
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Affiliation(s)
- Matthias M Müller
- Peter Grünberg Institute-Quantum Control (PGI-8), Forschungszentrum Jülich GmbH, D-52425 Germany
| | - Ressa S Said
- Institute for Quantum Optics & Center for Integrated Quantum Science and Technology, Universität Ulm, D-89081 Germany
| | - Fedor Jelezko
- Institute for Quantum Optics & Center for Integrated Quantum Science and Technology, Universität Ulm, D-89081 Germany
| | - Tommaso Calarco
- Peter Grünberg Institute-Quantum Control (PGI-8), Forschungszentrum Jülich GmbH, D-52425 Germany
- Institute for Theoretical Physics, University of Cologne, D-50937 Germany
| | - Simone Montangero
- Dipartimento di Fisica e Astronomia 'G. Galilei', Università degli Studi di Padova & INFN, Sezione di Padova, I-35131 Italy
- Padua Quantum Technology Center, Università degli Studi di Padova, I-35131 Italy
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33
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Yuan B, Wang W, Liu F, He H, Shan Z. Comparison of Lumped Oscillator Model and Energy Participation Ratio Methods in Designing Two-Dimensional Superconducting Quantum Chips. ENTROPY 2022; 24:e24060792. [PMID: 35741513 PMCID: PMC9222679 DOI: 10.3390/e24060792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 05/27/2022] [Accepted: 06/05/2022] [Indexed: 01/25/2023]
Abstract
Over the past two decades, superconducting quantum circuits have become one of the essential platforms for realizing quantum computers. The Hamiltonian of a superconducting quantum circuit system is the key to describing the dynamic evolution of the system. For this reason, various methods for analyzing the Hamiltonian of a superconducting quantum circuit system have been proposed, among which the LOM (Lumped Oscillator Model) and the EPR (Energy Participation Ratio) methods are the most popular ones. To analyze and improve the design methods of superconducting quantum chips, this paper compares the similarities and differences of the LOM and the EPR quantification methods. We verify the applicability of these two theoretical approaches to the design of 2D transmon quantum chips. By comparing the theoretically simulated results and the experimentally measured data at extremely low temperature, the errors between the theoretical calculation and observed measurement values of the two methods were summarized. Results show that the LOM method has more parameter outputs in data diversity and the qubit frequency calculation in LOM is more accurate. The reason is that in LOM more coupling between different systems are taken into consideration. These analyses would have reference significance for the design of superconducting quantum chips.
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34
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Deterministic Entanglement Swapping with Hybrid Discrete- and Continuous-Variable Systems. PHOTONICS 2022. [DOI: 10.3390/photonics9060368] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The study of entanglement between discrete and continuous variables is an important theoretical and experimental topic in quantum information processing, for which entanglement swapping is one of the interesting elements. Entanglement swapping allows two particles without interacting with each other in any way, to form an entangled state by the action of another pair of entangled particles. In this paper, we propose an experimentally feasible scheme to realize deterministic entanglement swapping in the hybrid system with discrete and continuous variables. The process is achieved by preparing two pairs of entangled states, each is formed by a qubit and two quasi-orthogonal coherent state elements of a cavity, performing a Bell-state analysis through nonlocal operations on the continuous variable states of the two cavities, and projecting the two qubits into a maximally entangled state. The present scheme may be applied to other physical systems sustaining such hybrid discrete and continuous forms, providing a typical paradigm for entanglement manipulation through deterministic swapping operations.
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35
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Error rate reduction of single-qubit gates via noise-aware decomposition into native gates. Sci Rep 2022; 12:6379. [PMID: 35430608 PMCID: PMC9013363 DOI: 10.1038/s41598-022-10339-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 04/04/2022] [Indexed: 11/28/2022] Open
Abstract
In the current era of Noisy Intermediate-Scale Quantum (NISQ) technology, the practical use of quantum computers remains inhibited by our inability to aptly decouple qubits from their environment to mitigate computational errors. In this paper, we introduce an approach by which knowledge of a qubit’s initial quantum state and the standard parameters describing its decoherence can be leveraged to mitigate the noise present during the execution of a single-qubit gate. We benchmark our protocol using cloud-based access to IBM quantum processors. On ibmq_rome, we demonstrate a reduction of the single-qubit error rate by 38%, from \documentclass[12pt]{minimal}
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\begin{document}$$T_2$$\end{document}T2 times have not drifted above 100 times their assumed values. The protocol can be used to reduce quantum state preparation errors, as well as to improve the fidelity of quantum circuits for which some knowledge of the qubits’ intermediate states can be inferred. This paper presents a pathway to using information about noise levels and quantum state distributions to significantly reduce error rates associated with quantum gates via optimized decomposition into native hardware gates.
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36
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Mohamed ABA, Rahman AU, Eleuch H. Measurement Uncertainty, Purity, and Entanglement Dynamics of Maximally Entangled Two Qubits Interacting Spatially with Isolated Cavities: Intrinsic Decoherence Effect. ENTROPY 2022; 24:e24040545. [PMID: 35455208 PMCID: PMC9030500 DOI: 10.3390/e24040545] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 03/26/2022] [Accepted: 03/31/2022] [Indexed: 02/04/2023]
Abstract
In a system of two charge-qubits that are initially prepared in a maximally entangled Bell’s state, the dynamics of quantum memory-assisted entropic uncertainty, purity, and negative entanglement are investigated. Isolated external cavity fields are considered in two different configurations: coherent-even coherent and even coherent cavity fields. For different initial cavity configurations, the temporal evolution of the final state of qubits and cavities is solved analytically. The effects of intrinsic decoherence and detuning strength on the dynamics of bipartite entropic uncertainty, purity and entanglement are explored. Depending on the field parameters, nonclassical correlations can be preserved. Nonclassical correlations and revival aspects appear to be significantly inhibited when intrinsic decoherence increases. Nonclassical correlations stay longer and have greater revivals due to the high detuning of the two qubits and the coherence strength of the initial cavity fields. Quantum memory-assisted entropic uncertainty and entropy have similar dynamics while the negativity presents fewer revivals in contrast.
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Affiliation(s)
- Abdel-Baset A. Mohamed
- Department of Mathematics, College of Science and Humanities in Al-Aflaj, Prince Sattam bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia
- Department of Mathematics, Faculty of Science, Assiut University, Assiut 71515, Egypt
- Correspondence:
| | - Atta Ur Rahman
- Key Laboratory of Aerospace Information Security and Trusted Computing, Wuhan University, Wuhan 430072, China;
| | - Hichem Eleuch
- Department of Applied Physics and Astronomy, University of Sharjah, Sharjah P.O. Box 26666, United Arab Emirates;
- College of Arts and Sciences, Abu Dhabi University, Abu Dhabi P.O. Box 59911, United Arab Emirates
- Institute for Quantum Science and Engineering, Texas A&M University, College Station, TX 77843, USA
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37
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Li Y, Xin T, Qiu C, Li K, Liu G, Li J, Wan Y, Lu D. Dynamical-Invariant-based Holonomic Quantum Gates: Theory and Experiment. FUNDAMENTAL RESEARCH 2022. [DOI: 10.1016/j.fmre.2021.11.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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38
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Belousov Y, Man’ko VI, Migliore A, Sergi A, Messina A. Symmetry-Induced Emergence of a Pseudo-Qutrit in the Dipolar Coupling of Two Qubits. ENTROPY 2022; 24:e24020223. [PMID: 35205517 PMCID: PMC8871430 DOI: 10.3390/e24020223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 01/27/2022] [Accepted: 01/28/2022] [Indexed: 02/05/2023]
Abstract
We investigate a system of two identical and distinguishable spins 1/2, with a direct magnetic dipole–dipole interaction, in an external magnetic field. Constraining the hyperfine tensor to exhibit axial symmetry generates the notable symmetry properties of the corresponding Hamiltonian model. In fact, we show that the reduction of the anisotropy induces the invariance of the Hamiltonian in the 3×3 subspace of the Hilbert space of the two spins in which S^2 invariably assumes its highest eigenvalue of 2. By means of appropriate mapping, it is then possible to choose initial density matrices of the two-spin system that evolve in such a way as to exactly simulate the time evolution of a pseudo-qutrit, in the sense that the the actual two-spin system nests the subdynamics of a qutrit regardless of the strength of the magnetic field. The occurrence of this dynamic similitude is investigated using two types of representation for the initial density matrix of the two spins. We show that the qutrit state emerges when the initial polarizations and probability vectors of the two spins are equal to each other. Further restrictions on the components of the probability vectors are reported and discussed.
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Affiliation(s)
- Yury Belousov
- Moscow Institute of Physics and Technology, Institutskii Per. 9, Dolgoprudny, 141700 Moscow, Russia;
- Terra Quantum AG, St. Gallerstrasse 16A, 9400 Rorschach, Switzerland
| | - Vladimir I. Man’ko
- Lebedev Physical Institute, Leninskii Prospect 53, 119991 Moscow, Russia;
| | - Agostino Migliore
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy;
| | - Alessandro Sergi
- Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra, Università degli Studi di Messina, Viale F. Stagno d’Alcontres 31, 98166 Messina, Italy;
- Istituto Nazionale di Fisica Nucleare, Sez. di Catania, 95123 Catania, Italy
- Institute of Systems Science, Durban University of Technology, P.O. Box 1334, Durban 4000, South Africa
| | - Antonino Messina
- Dipartimento di Matematica ed Informatica dell’Università di Palermo, Via Archirafi 34, 90123 Palermo, Italy
- Correspondence:
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39
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He S, Li Y, Wei LF. Group delay controls of the photons transmitting through two cavities coupled by an artificial atomic ensemble: controllable electromagnetically induced transparency-like effects. OPTICS EXPRESS 2022; 30:721-739. [PMID: 35209257 DOI: 10.1364/oe.440027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 12/14/2021] [Indexed: 06/14/2023]
Abstract
As one of the typical quantum coherence phenomena, electromagnetically induced transparency (EIT) has been extensively applied to implement various quantum coherent manipulations, typically, e.g., optical quantum memories, photonic switches, and optical quantum computations, etc. By applying the input-output theory to the photonic transports through two cavities dispersively coupled by an artificial two-level atomic ensemble, we show here that the EIT-like effects could be observed. Particularly, the transparency windows and phase shift spectra of the transmitting photons could be engineered by manipulating the atomic levels in the ensemble to adjust the effective coupling strength between the cavities. As a consequence, the group delays of the transmitting photons can be manipulated by using the EIT-like effects. The proposal is demonstrated specifically with the experimental superconducting coplanar waveguide resonators coupled by the voltage-biased electrons on liquid Helium.
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40
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Rolczynski BS, Díaz SA, Kim YC, Medintz IL, Cunningham PD, Melinger JS. Understanding Disorder, Vibronic Structure, and Delocalization in Electronically Coupled Dimers on DNA Duplexes. J Phys Chem A 2021; 125:9632-9644. [PMID: 34709821 DOI: 10.1021/acs.jpca.1c07205] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Structural DNA nanotechnology is a promising approach to create chromophore networks with modular structures and Hamiltonians to control the material's functions. The functional behaviors of these systems depend on the interactions of the chromophores' vibronic states, as well as interactions with their environment. To optimize their functions, it is necessary to characterize the chromophore network's structural and energetic properties, including the electronic delocalization in some cases. In this study, parameters of interest are deduced in DNA-scaffolded Cyanine 3 and Cyanine 5 dimers. The methods include steady-state optical measurements, physical modeling, and a genetic algorithm approach. The parameters include the chromophore network's vibronic Hamiltonian, molecular positions, transition dipole orientations, and environmentally induced energy broadening. Additionally, the study uses temperature-dependent optical measurements to characterize the spectral broadening further. These combined results reveal the quantum mechanical delocalization, which is important for functions like coherent energy transport and quantum information applications.
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Affiliation(s)
- Brian S Rolczynski
- Electronics Science and Technology Division, Code 6800, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Sebastián A Díaz
- Center for Bio/Molecular Science and Engineering, Code 6900, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Young C Kim
- Materials Science and Technology Division, Code 6300, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Igor L Medintz
- Center for Bio/Molecular Science and Engineering, Code 6900, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Paul D Cunningham
- Electronics Science and Technology Division, Code 6800, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Joseph S Melinger
- Electronics Science and Technology Division, Code 6800, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States
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41
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Ahmed S, Sánchez Muñoz C, Nori F, Kockum AF. Quantum State Tomography with Conditional Generative Adversarial Networks. PHYSICAL REVIEW LETTERS 2021; 127:140502. [PMID: 34652197 DOI: 10.1103/physrevlett.127.140502] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 05/21/2021] [Accepted: 06/10/2021] [Indexed: 06/13/2023]
Abstract
Quantum state tomography (QST) is a challenging task in intermediate-scale quantum devices. Here, we apply conditional generative adversarial networks (CGANs) to QST. In the CGAN framework, two dueling neural networks, a generator and a discriminator, learn multimodal models from data. We augment a CGAN with custom neural-network layers that enable conversion of output from any standard neural network into a physical density matrix. To reconstruct the density matrix, the generator and discriminator networks train each other on data using standard gradient-based methods. We demonstrate that our QST-CGAN reconstructs optical quantum states with high fidelity, using orders of magnitude fewer iterative steps, and less data, than both accelerated projected-gradient-based and iterative maximum-likelihood estimation. We also show that the QST-CGAN can reconstruct a quantum state in a single evaluation of the generator network if it has been pretrained on similar quantum states.
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Affiliation(s)
- Shahnawaz Ahmed
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Carlos Sánchez Muñoz
- Departamento de Fisica Teorica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autonoma de Madrid, Madrid 28049, Spain
| | - Franco Nori
- Theoretical Quantum Physics Laboratory, RIKEN Cluster for Pioneering Research, Wako-shi, Saitama 351-0198, Japan
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040, USA
| | - Anton Frisk Kockum
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
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42
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Li Y, Zaki N, Garlea VO, Savici AT, Fobes D, Xu Z, Camino F, Petrovic C, Gu G, Johnson PD, Tranquada JM, Zaliznyak IA. Electronic properties of the bulk and surface states of Fe 1+yTe 1-xSe x. NATURE MATERIALS 2021; 20:1221-1227. [PMID: 33888904 DOI: 10.1038/s41563-021-00984-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 03/12/2021] [Indexed: 06/12/2023]
Abstract
The idea of employing non-Abelian statistics for error-free quantum computing ignited interest in reports of topological surface superconductivity and Majorana zero modes (MZMs) in FeTe0.55Se0.45. However, the topological features and superconducting properties are not observed uniformly across the sample surface. The understanding and practical control of these electronic inhomogeneities present a prominent challenge for potential applications. Here, we combine neutron scattering, scanning angle-resolved photoemission spectroscopy, and microprobe composition and resistivity measurements to characterize the electronic state of Fe1+yTe1-xSex. We establish a phase diagram in which the superconductivity is observed only at sufficiently low Fe concentration, in association with distinct antiferromagnetic correlations, whereas the coexisting topological surface state occurs only at sufficiently high Te concentration. We find that FeTe0.55Se0.45 is located very close to both phase boundaries, which explains the inhomogeneity of superconducting and topological states. Our results demonstrate the compositional control required for use of topological MZMs in practical applications.
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Affiliation(s)
- Yangmu Li
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY, USA
| | - Nader Zaki
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY, USA
| | - Vasile O Garlea
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Andrei T Savici
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - David Fobes
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY, USA
| | - Zhijun Xu
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY, USA
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA
- Department of Materials Science and Engineering, University of Maryland, College Park, MD, USA
| | - Fernando Camino
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY, USA
| | - Cedomir Petrovic
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY, USA
| | - Genda Gu
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY, USA
| | - Peter D Johnson
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY, USA
| | - John M Tranquada
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY, USA
| | - Igor A Zaliznyak
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY, USA.
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43
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Nguyen DH, Sidorenko A, Taupin M, Knebel G, Lapertot G, Schuberth E, Paschen S. Superconductivity in an extreme strange metal. Nat Commun 2021; 12:4341. [PMID: 34290244 PMCID: PMC8295387 DOI: 10.1038/s41467-021-24670-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 06/28/2021] [Indexed: 11/09/2022] Open
Abstract
Some of the highest-transition-temperature superconductors across various materials classes exhibit linear-in-temperature 'strange metal' or 'Planckian' electrical resistivities in their normal state. It is thus believed by many that this behavior holds the key to unlock the secrets of high-temperature superconductivity. However, these materials typically display complex phase diagrams governed by various competing energy scales, making an unambiguous identification of the physics at play difficult. Here we use electrical resistivity measurements into the micro-Kelvin regime to discover superconductivity condensing out of an extreme strange metal state-with linear resistivity over 3.5 orders of magnitude in temperature. We propose that the Cooper pairing is mediated by the modes associated with a recently evidenced dynamical charge localization-delocalization transition, a mechanism that may well be pertinent also in other strange metal superconductors.
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Affiliation(s)
- D H Nguyen
- Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, Vienna, Austria
| | - A Sidorenko
- Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, Vienna, Austria
| | - M Taupin
- Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, Vienna, Austria
| | - G Knebel
- Université Grenoble Alpes, CEA, Grenoble INP, IRIG, PHELIQS, Grenoble, France
| | - G Lapertot
- Université Grenoble Alpes, CEA, Grenoble INP, IRIG, PHELIQS, Grenoble, France
| | - E Schuberth
- Technische Universität München, Garching, Germany
| | - S Paschen
- Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, Vienna, Austria.
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Zhao T, Wu SP, Yang GQ, Huang GM, Li GX. Ultranarrow spectral line of the radiation in double qubit-cavity ultrastrong coupling system. OPTICS EXPRESS 2021; 29:23939-23952. [PMID: 34614648 DOI: 10.1364/oe.432358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 07/05/2021] [Indexed: 06/13/2023]
Abstract
The ultrastrongly coupling (USC) system has very important research significance in quantum simulation and quantum computing. In this paper, the ultranarrow spectrum of a circuit QED system with two qubits ultrastrongly coupled to a single-mode cavity is studied. In the regime of USC, the JC model breaks down and the counter-rotating terms in the quantum Rabi Hamiltonian leads to the level anti-crossing in the energy spectrum. Choosing a single-photon driving field at the point of avoided-level crossing, we can get an equivalent four-level dressed state model, in which the dissipation of the two intermediate states is only related to the qubits decay. Due to the electron shelving of these two metastable states, a narrow peak appears in the cavity emission spectrum. Furthermore, we find that the physical origin for the spectral narrowing is the vacuum-induced quantum interference between two transition pathways. And this interference effect couples the slowly decaying incoherent components of the density matrix into the equations of the sidebands. This result provides a possibility for the study of quantum interference effect in the USC system.
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45
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de Vries FK, Portolés E, Zheng G, Taniguchi T, Watanabe K, Ihn T, Ensslin K, Rickhaus P. Gate-defined Josephson junctions in magic-angle twisted bilayer graphene. NATURE NANOTECHNOLOGY 2021; 16:760-763. [PMID: 33941917 DOI: 10.1038/s41565-021-00896-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/10/2021] [Indexed: 05/12/2023]
Abstract
In situ electrostatic control of two-dimensional superconductivity1 is commonly limited due to large charge carrier densities, and gate-defined Josephson junctions are therefore rare2,3. Magic-angle twisted bilayer graphene (MATBG)4-8 has recently emerged as a versatile platform that combines metallic, superconducting, magnetic and insulating phases in a single crystal9-14. Although MATBG appears to be an ideal two-dimensional platform for gate-tunable superconductivity9,11,13, progress towards practical implementations has been hindered by the need for well-defined gated regions. Here we use multilayer gate technology to create a device based on two distinct phases in adjustable regions of MATBG. We electrostatically define the superconducting and insulating regions of a Josephson junction and observe tunable d.c. and a.c. Josephson effects15,16. The ability to tune the superconducting state within a single material circumvents interface and fabrication challenges, which are common in multimaterial nanostructures. This work is an initial step towards devices where gate-defined correlated states are connected in single-crystal nanostructures. We envision applications in superconducting electronics17,18 and quantum information technology19,20.
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Affiliation(s)
| | - Elías Portolés
- Solid State Physics Laboratory, ETH Zurich, Zurich, Switzerland
| | - Giulia Zheng
- Solid State Physics Laboratory, ETH Zurich, Zurich, Switzerland
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Thomas Ihn
- Solid State Physics Laboratory, ETH Zurich, Zurich, Switzerland
| | - Klaus Ensslin
- Solid State Physics Laboratory, ETH Zurich, Zurich, Switzerland
| | - Peter Rickhaus
- Solid State Physics Laboratory, ETH Zurich, Zurich, Switzerland.
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46
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Petiziol F, Sameti M, Carretta S, Wimberger S, Mintert F. Quantum Simulation of Three-Body Interactions in Weakly Driven Quantum Systems. PHYSICAL REVIEW LETTERS 2021; 126:250504. [PMID: 34241528 DOI: 10.1103/physrevlett.126.250504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 03/17/2021] [Accepted: 05/07/2021] [Indexed: 06/13/2023]
Abstract
The realization of effective Hamiltonians featuring many-body interactions beyond pairwise coupling would enable the quantum simulation of central models underpinning topological physics and quantum computation. We overcome crucial limitations of perturbative Floquet engineering and discuss the highly accurate realization of a purely three-body Hamiltonian in superconducting circuits and molecular nanomagnets.
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Affiliation(s)
- Francesco Petiziol
- Università di Parma, Dipartimento di Scienze Matematiche, Fisiche e Informatiche, I-43124 Parma, Italy
- UdR Parma, INSTM, I-43124 Parma, Italy
| | - Mahdi Sameti
- Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
| | - Stefano Carretta
- Università di Parma, Dipartimento di Scienze Matematiche, Fisiche e Informatiche, I-43124 Parma, Italy
- UdR Parma, INSTM, I-43124 Parma, Italy
| | - Sandro Wimberger
- Università di Parma, Dipartimento di Scienze Matematiche, Fisiche e Informatiche, I-43124 Parma, Italy
- INFN, Sezione di Milano Bicocca, Gruppo Collegato di Parma, Parma, Italy
| | - Florian Mintert
- Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
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Sharifi J. Superconductor qubits hamiltonian approximations effect on quantum state evolution and control. Sci Rep 2021; 11:12791. [PMID: 34140590 PMCID: PMC8211851 DOI: 10.1038/s41598-021-92290-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 05/28/2021] [Indexed: 12/02/2022] Open
Abstract
Microwave IQ-mixer controllers are designed for the three approximated Hamiltonians of charge, phase and flux qubits and the controllers are exerted both on approximate and precise quantum system models. The controlled qubits are for the implementation of the two quantum-gates with these three fundamental types of qubits, Quantum NOT-gate and Hadamard-gate. In the charge-qubit, for implementation of both gates, in the approximated and precise model, we observed different controlled trajectories. But fortunately, applying the controller designed for the approximated system over the precise system leads to the passing of the quantum state from the desired state sooner that the expected time. Phase-qubit and flux qubit have similar behaviour under the control system action. In both of them, the implementation of NOT-gate operation led to same trajectories which arrive at final goal state at different times. But in both of those two qubits for implementation of Hadamard-gate, desired trajectory and precise trajectory have some angle of deviation, then by exerting the approximated design controller to precise system, it caused the quantum state to approach the goal state for Hadamard gate implementation, and since the quantum state does not completely reach the goal state, we can not obtain very high gate fidelity.
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Affiliation(s)
- Javad Sharifi
- Electrical and Computer Engineering Department, Qom University of Technology, Qom, 37181-46645, Iran.
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Casado-Pascual J, Lamata L, Reynoso AA. Spin dynamics under the influence of elliptically rotating fields: Extracting the field topology from time-averaged quantities. Phys Rev E 2021; 103:052139. [PMID: 34134222 DOI: 10.1103/physreve.103.052139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Accepted: 05/07/2021] [Indexed: 11/07/2022]
Abstract
Systems that can be effectively described as a localized spin-s particle subject to time-dependent fields have attracted a great deal of interest due to, among other things, their relevance for quantum technologies. Establishing analytical relationships between the topological features of the applied fields and certain time-averaged quantities of the spin can provide important information for the theoretical understanding of these systems. Here, we address this question in the case of a localized spin-s particle subject to a static magnetic field coplanar to a coexisting elliptically rotating magnetic field. The total field periodically traces out an ellipse which encloses the origin of the coordinate system or not, depending on the values taken on by the static and the rotating components. As a result, two regimes with different topological properties characterized by the winding number of the total field emerge: the winding number is 1 if the origin lies inside the ellipse, and 0 if it lies outside. We show that the time average of the energy associated with the rotating component of the magnetic field is always proportional to the time average of the out-of-plane component of the expectation value of the spin. Moreover, the product of the signs of these two time-averaged quantities is uniquely determined by the topology of the total field and, consequently, provides a measurable indicator of this topology. We also propose an implementation of these theoretical results in a trapped-ion quantum system. Remarkably, our findings are valid in the totality of the parameter space and regardless of the initial state of the spin. In particular, when the system is prepared in a Floquet state, we demonstrate that the quasienergies, as a function of the driving amplitude at constant eccentricity, have stationary points at the topological transition boundary. The ability of the topological indicator proposed here to accurately locate the abrupt topological transition can have practical applications for the determination of unknown parameters appearing in the Hamiltonian. In addition, our predictions about the quasienergies can assist in the interpretation of conductance measurements in transport experiments with spin carriers in mesoscopic rings.
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Affiliation(s)
- Jesús Casado-Pascual
- Física Teórica, Universidad de Sevilla, Apartado de Correos 1065, 41080 Sevilla, Spain
| | - Lucas Lamata
- Departamento de Física Atómica, Molecular y Nuclear, Universidad de Sevilla, Apartado de Correos 1065, 41080 Sevilla, Spain
| | - Andrés A Reynoso
- INN-CONICET, Centro Atómico Bariloche, 8400, San Carlos de Bariloche, Argentina
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50
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Dajka J. Currents in a Quantum Nanoring Controlled by Non-Classical Electromagnetic Field. ENTROPY 2021; 23:e23060652. [PMID: 34070969 PMCID: PMC8224575 DOI: 10.3390/e23060652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 05/18/2021] [Accepted: 05/19/2021] [Indexed: 11/23/2022]
Abstract
Quantum ring accommodating interacting spin-less fermions threaded by magnetic flux with a non-classical component added to a static, inducing persistent current, is considered. It is investigated how current flowing in the ring becomes affected by a state of non-classical flux and how Coulomb interaction between fermions influences entanglement of quantum ring and the driving field. In particular it is shown that in an absence of decoherence and under certain conditions fermion–fermion interaction is necessary for a ring–field entanglement to occur.
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Affiliation(s)
- Jerzy Dajka
- Institute of Physics, University of Silesia in Katowice, 40-007 Katowice, Poland;
- Silesian Center for Education and Interdisciplinary Research, University of Silesia in Katowice, 41-500 Chorzów, Poland
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