1
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Kono S, Pan J, Chegnizadeh M, Wang X, Youssefi A, Scigliuzzo M, Kippenberg TJ. Mechanically induced correlated errors on superconducting qubits with relaxation times exceeding 0.4 ms. Nat Commun 2024; 15:3950. [PMID: 38729959 PMCID: PMC11087564 DOI: 10.1038/s41467-024-48230-3] [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: 07/06/2023] [Accepted: 04/24/2024] [Indexed: 05/12/2024] Open
Abstract
Superconducting qubits are among the most advanced candidates for achieving fault-tolerant quantum computing. Despite recent significant advancements in the qubit lifetimes, the origin of the loss mechanism for state-of-the-art qubits is still subject to investigation. Furthermore, the successful implementation of quantum error correction requires negligible correlated errors between qubits. Here, we realize long-lived superconducting transmon qubits that exhibit fluctuating lifetimes, averaging 0.2 ms and exceeding 0.4 ms - corresponding to quality factors above 5 million and 10 million, respectively. We then investigate their dominant error mechanism. By introducing novel time-resolved error measurements that are synchronized with the operation of the pulse tube cooler in a dilution refrigerator, we find that mechanical vibrations from the pulse tube induce nonequilibrium dynamics in highly coherent qubits, leading to their correlated bit-flip errors. Our findings not only deepen our understanding of the qubit error mechanisms but also provide valuable insights into potential error-mitigation strategies for achieving fault tolerance by decoupling superconducting qubits from their mechanical environments.
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Affiliation(s)
- Shingo Kono
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland.
| | - Jiahe Pan
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Mahdi Chegnizadeh
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Xuxin Wang
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Amir Youssefi
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Marco Scigliuzzo
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Tobias J Kippenberg
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland.
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2
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Zou J, Bosco S, Loss D. Spatially correlated classical and quantum noise in driven qubits. NPJ QUANTUM INFORMATION 2024; 10:46. [PMID: 38706554 PMCID: PMC11062932 DOI: 10.1038/s41534-024-00842-9] [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: 08/27/2023] [Accepted: 04/17/2024] [Indexed: 05/07/2024]
Abstract
Correlated noise across multiple qubits poses a significant challenge for achieving scalable and fault-tolerant quantum processors. Despite recent experimental efforts to quantify this noise in various qubit architectures, a comprehensive understanding of its role in qubit dynamics remains elusive. Here, we present an analytical study of the dynamics of driven qubits under spatially correlated noise, including both Markovian and non-Markovian noise. Surprisingly, we find that by operating the qubit system at low temperatures, where correlated quantum noise plays an important role, significant long-lived entanglement between qubits can be generated. Importantly, this generation process can be controlled on-demand by turning the qubit driving on and off. On the other hand, we demonstrate that by operating the system at a higher temperature, the crosstalk between qubits induced by the correlated noise is unexpectedly suppressed. We finally reveal the impact of spatio-temporally correlated 1/f noise on the decoherence rate, and how its temporal correlations restore lost entanglement. Our findings provide critical insights into not only suppressing crosstalk between qubits caused by correlated noise but also in effectively leveraging such noise as a beneficial resource for controlled entanglement generation.
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Affiliation(s)
- Ji Zou
- Department of Physics, University of Basel, Basel, Switzerland
| | - Stefano Bosco
- Department of Physics, University of Basel, Basel, Switzerland
| | - Daniel Loss
- Department of Physics, University of Basel, Basel, Switzerland
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3
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Das A, Kurinsky N, Leane RK. Dark Matter Induced Power in Quantum Devices. PHYSICAL REVIEW LETTERS 2024; 132:121801. [PMID: 38579214 DOI: 10.1103/physrevlett.132.121801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 01/19/2024] [Accepted: 02/21/2024] [Indexed: 04/07/2024]
Abstract
We point out that power measurements of single quasiparticle devices open a new avenue to detect dark matter (DM). The threshold of these devices is set by the Cooper pair binding energy, and is therefore so low that they can detect DM as light as about an MeV incoming from the Galactic halo, as well as the low-velocity thermalized DM component potentially present in the Earth. Using existing power measurements with these new devices, as well as power measurements with SuperCDMS-CPD, we set new constraints on the spin-independent DM scattering cross section for DM masses from about 10 MeV to 10 GeV. We outline future directions to improve sensitivity to both halo DM and a thermalized DM population in the Earth using power deposition in quantum devices.
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Affiliation(s)
- Anirban Das
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - Noah Kurinsky
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, California 94035, USA
| | - Rebecca K Leane
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, California 94035, USA
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4
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Shirizly L, Misguich G, Landa H. Dissipative Dynamics of Graph-State Stabilizers with Superconducting Qubits. PHYSICAL REVIEW LETTERS 2024; 132:010601. [PMID: 38242658 DOI: 10.1103/physrevlett.132.010601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 11/21/2023] [Accepted: 11/29/2023] [Indexed: 01/21/2024]
Abstract
We study experimentally and numerically the noisy evolution of multipartite entangled states, focusing on superconducting qubit devices accessible via the cloud. We find that a valid modeling of the dynamics requires one to properly account for coherent frequency shifts, caused by stochastic charge-parity fluctuations. We introduce an approach modeling the charge-parity splitting using an extended Markovian environment. This approach is numerically scalable to tens of qubits, allowing us to simulate efficiently the dissipative dynamics of some large multiqubit states. Probing the continuous-time dynamics of increasingly larger and more complex initial states with up to 12 coupled qubits in a ring-graph state, we obtain a good agreement of the experiments and simulations. We show that the underlying many-body dynamics generate decays and revivals of stabilizers, which are used extensively in the context of quantum error correction. Furthermore, we demonstrate the mitigation of 2-qubit coherent interactions (crosstalk) using tailored dynamical decoupling sequences. Our noise model and the numerical approach can be valuable to advance the understanding of error correction and mitigation and invite further investigations of their dynamics.
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Affiliation(s)
- Liran Shirizly
- IBM Quantum, IBM Research - Israel, Haifa University Campus, Mount Carmel, Haifa 31905, Israel
| | - Grégoire Misguich
- Université Paris-Saclay, CNRS, CEA, Institut de Physique Théorique, 91191 Gif-sur-Yvette, France
| | - Haggai Landa
- IBM Quantum, IBM Research - Israel, Haifa University Campus, Mount Carmel, Haifa 31905, Israel
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5
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Liu CH, Harrison DC, Patel S, Wilen CD, Rafferty O, Shearrow A, Ballard A, Iaia V, Ku J, Plourde BLT, McDermott R. Quasiparticle Poisoning of Superconducting Qubits from Resonant Absorption of Pair-Breaking Photons. PHYSICAL REVIEW LETTERS 2024; 132:017001. [PMID: 38242669 DOI: 10.1103/physrevlett.132.017001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 11/22/2023] [Accepted: 11/29/2023] [Indexed: 01/21/2024]
Abstract
The ideal superconductor provides a pristine environment for the delicate states of a quantum computer: because there is an energy gap to excitations, there are no spurious modes with which the qubits can interact, causing irreversible decay of the quantum state. As a practical matter, however, there exists a high density of excitations out of the superconducting ground state even at ultralow temperature; these are known as quasiparticles. Observed quasiparticle densities are of order 1 μm^{-3}, tens of orders of magnitude greater than the equilibrium density expected from theory. Nonequilibrium quasiparticles extract energy from the qubit mode and can induce dephasing. Here we show that a dominant mechanism for quasiparticle poisoning is direct absorption of high-energy photons at the qubit junction. We use a Josephson junction-based photon source to controllably dose qubit circuits with millimeter-wave radiation, and we use an interferometric quantum gate sequence to reconstruct the charge parity of the qubit. We find that the structure of the qubit itself acts as a resonant antenna for millimeter-wave radiation, providing an efficient path for photons to generate quasiparticles. A deep understanding of this physics will pave the way to realization of next-generation superconducting qubits that are robust against quasiparticle poisoning.
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Affiliation(s)
- C H Liu
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - D C Harrison
- Intelligence Community Postdoctoral Research Fellowship Program, Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - S Patel
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - C D Wilen
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - O Rafferty
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - A Shearrow
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - A Ballard
- Department of Physics, Syracuse University, Syracuse, New York 13244, USA
| | - V Iaia
- Department of Physics, Syracuse University, Syracuse, New York 13244, USA
| | - J Ku
- Department of Physics, Syracuse University, Syracuse, New York 13244, USA
| | - B L T Plourde
- Department of Physics, Syracuse University, Syracuse, New York 13244, USA
| | - R McDermott
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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6
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Dodge K, Liu Y, Klots AR, Cole B, Shearrow A, Senatore M, Zhu S, Ioffe LB, McDermott R, Plourde BLT. Hardware Implementation of Quantum Stabilizers in Superconducting Circuits. PHYSICAL REVIEW LETTERS 2023; 131:150602. [PMID: 37897769 DOI: 10.1103/physrevlett.131.150602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Accepted: 09/07/2023] [Indexed: 10/30/2023]
Abstract
Stabilizer operations are at the heart of quantum error correction and are typically implemented in software-controlled entangling gates and measurements of groups of qubits. Alternatively, qubits can be designed so that the Hamiltonian corresponds directly to a stabilizer for protecting quantum information. We demonstrate such a hardware implementation of stabilizers in a superconducting circuit composed of chains of π-periodic Josephson elements. With local on-chip flux and charge biasing, we observe a progressive softening of the energy band dispersion with respect to flux as the number of frustrated plaquette elements is increased, in close agreement with our numerical modeling.
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Affiliation(s)
- K Dodge
- Department of Physics, Syracuse University, Syracuse, New York 13244-1130, USA
| | - Y Liu
- Department of Physics, Syracuse University, Syracuse, New York 13244-1130, USA
| | - A R Klots
- Google Quantum AI, Santa Barbara, California 93111, USA
| | - B Cole
- Department of Physics, Syracuse University, Syracuse, New York 13244-1130, USA
| | - A Shearrow
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - M Senatore
- Department of Physics, Syracuse University, Syracuse, New York 13244-1130, USA
| | - S Zhu
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - L B Ioffe
- Google Quantum AI, Santa Barbara, California 93111, USA
| | - R McDermott
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - B L T Plourde
- Department of Physics, Syracuse University, Syracuse, New York 13244-1130, USA
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7
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Lingenfelter A, Clerk AA. Surpassing spectator qubits with photonic modes and continuous measurement for Heisenberg-limited noise mitigation. NPJ QUANTUM INFORMATION 2023; 9:81. [PMID: 38726362 PMCID: PMC11080661 DOI: 10.1038/s41534-023-00748-y] [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: 01/09/2023] [Accepted: 07/25/2023] [Indexed: 05/12/2024]
Abstract
Noise is an ever-present challenge to the creation and preservation of fragile quantum states. Recent work suggests that spatial noise correlations can be harnessed as a resource for noise mitigation via the use of spectator qubits to measure environmental noise. In this work we generalize this concept from spectator qubits to a spectator mode: a photonic mode which continuously measures spatially correlated classical dephasing noise and applies a continuous correction drive to frequency-tunable data qubits. Our analysis shows that by using many photon states, spectator modes can surpass many of the quantum measurement constraints that limit spectator qubit approaches. We also find that long-time data qubit dephasing can be arbitrarily suppressed, even for white noise dephasing. Further, using a squeezing (parametric) drive, the error in the spectator mode approach can exhibit Heisenberg-limited scaling in the number of photons used. We also show that spectator mode noise mitigation can be implemented completely autonomously using engineered dissipation. In this case no explicit measurement or processing of a classical measurement record is needed. Our work establishes spectator modes as a potentially powerful alternative to spectator qubits for noise mitigation.
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Affiliation(s)
- Andrew Lingenfelter
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637 USA
- Department of Physics, University of Chicago, Chicago, IL 60637 USA
| | - Aashish A. Clerk
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637 USA
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8
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Kitzman JM, Lane JR, Undershute C, Harrington PM, Beysengulov NR, Mikolas CA, Murch KW, Pollanen J. Phononic bath engineering of a superconducting qubit. Nat Commun 2023; 14:3910. [PMID: 37400431 DOI: 10.1038/s41467-023-39682-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 06/22/2023] [Indexed: 07/05/2023] Open
Abstract
Phonons, the ubiquitous quanta of vibrational energy, play a vital role in the performance of quantum technologies. Conversely, unintended coupling to phonons degrades qubit performance and can lead to correlated errors in superconducting qubit systems. Regardless of whether phonons play an enabling or deleterious role, they do not typically admit control over their spectral properties, nor the possibility of engineering their dissipation to be used as a resource. Here we show that coupling a superconducting qubit to a bath of piezoelectric surface acoustic wave phonons enables a novel platform for investigating open quantum systems. By shaping the loss spectrum of the qubit via the bath of lossy surface phonons, we demonstrate preparation and dynamical stabilization of superposition states through the combined effects of drive and dissipation. These experiments highlight the versatility of engineered phononic dissipation and advance the understanding of mechanical losses in superconducting qubit systems.
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Affiliation(s)
- J M Kitzman
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI, 48824, USA.
| | - J R Lane
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI, 48824, USA
| | - C Undershute
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI, 48824, USA
| | - P M Harrington
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - N R Beysengulov
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI, 48824, USA
| | - C A Mikolas
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI, 48824, USA
| | - K W Murch
- Department of Physics, Washington University, St. Louis, MO, 63130, USA
| | - J Pollanen
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI, 48824, USA.
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9
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Lucas M, Danilov AV, Levitin LV, Jayaraman A, Casey AJ, Faoro L, Tzalenchuk AY, Kubatkin SE, Saunders J, de Graaf SE. Quantum bath suppression in a superconducting circuit by immersion cooling. Nat Commun 2023; 14:3522. [PMID: 37316500 DOI: 10.1038/s41467-023-39249-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 06/02/2023] [Indexed: 06/16/2023] Open
Abstract
Quantum circuits interact with the environment via several temperature-dependent degrees of freedom. Multiple experiments to-date have shown that most properties of superconducting devices appear to plateau out at T ≈ 50 mK - far above the refrigerator base temperature. This is for example reflected in the thermal state population of qubits, in excess numbers of quasiparticles, and polarisation of surface spins - factors contributing to reduced coherence. We demonstrate how to remove this thermal constraint by operating a circuit immersed in liquid 3He. This allows to efficiently cool the decohering environment of a superconducting resonator, and we see a continuous change in measured physical quantities down to previously unexplored sub-mK temperatures. The 3He acts as a heat sink which increases the energy relaxation rate of the quantum bath coupled to the circuit a thousand times, yet the suppressed bath does not introduce additional circuit losses or noise. Such quantum bath suppression can reduce decoherence in quantum circuits and opens a route for both thermal and coherence management in quantum processors.
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Affiliation(s)
- M Lucas
- Physics Department, Royal Holloway University of London, Egham, UK
| | - A V Danilov
- Department of Microtechnology and Nanoscience MC2, Chalmers University of Technology, SE-412 96, Göteborg, Sweden
| | - L V Levitin
- Physics Department, Royal Holloway University of London, Egham, UK
| | - A Jayaraman
- Department of Microtechnology and Nanoscience MC2, Chalmers University of Technology, SE-412 96, Göteborg, Sweden
| | - A J Casey
- Physics Department, Royal Holloway University of London, Egham, UK
| | - L Faoro
- Google Quantum AI, Google Research, Mountain View, CA, USA
| | - A Ya Tzalenchuk
- Physics Department, Royal Holloway University of London, Egham, UK
- National Physical Laboratory, Teddington, TW11 0LW, UK
| | - S E Kubatkin
- Department of Microtechnology and Nanoscience MC2, Chalmers University of Technology, SE-412 96, Göteborg, Sweden
| | - J Saunders
- Physics Department, Royal Holloway University of London, Egham, UK
| | - S E de Graaf
- National Physical Laboratory, Teddington, TW11 0LW, UK.
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10
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Singh K, Bradley CE, Anand S, Ramesh V, White R, Bernien H. Mid-circuit correction of correlated phase errors using an array of spectator qubits. Science 2023:eade5337. [PMID: 37228222 DOI: 10.1126/science.ade5337] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 05/15/2023] [Indexed: 05/27/2023]
Abstract
Scaling up invariably error-prone quantum processors is a formidable challenge. Although quantum error correction ultimately promises fault-tolerant operation, the required qubit overhead and error thresholds are daunting. In a complementary proposal, co-located, auxiliary 'spectator' qubits act as in-situ probes of noise, and enable real-time, coherent corrections of data qubit errors. We use an array of cesium spectator qubits to correct correlated phase errors on an array of rubidium data qubits. By combining in-sequence readout, data processing, and feed-forward operations, these correlated errors are suppressed within the execution of the quantum circuit. The protocol is broadly applicable to quantum information platforms, and establishes key tools for scaling neutral-atom quantum processors: mid-circuit readout of atom arrays, real-time processing and feed-forward, and coherent mid-circuit reloading of atomic qubits.
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Affiliation(s)
- K Singh
- Intelligence Community Postdoctoral Research Fellowship Program, Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA
| | - C E Bradley
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA
| | - S Anand
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA
| | - V Ramesh
- Department of Physics, University of Chicago, Chicago, IL 60637, USA
| | - R White
- Department of Physics, University of Chicago, Chicago, IL 60637, USA
| | - H Bernien
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA
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11
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Han C, Meir Y, Sela E. Realistic Protocol to Measure Entanglement at Finite Temperatures. PHYSICAL REVIEW LETTERS 2023; 130:136201. [PMID: 37067316 DOI: 10.1103/physrevlett.130.136201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 03/14/2023] [Indexed: 06/19/2023]
Abstract
It is desirable to relate entanglement of many-body systems to measurable observables. In systems with a conserved charge, it was recently shown that the number entanglement entropy (NEE)-i.e., the entropy change due to an unselective subsystem charge measurement-is an entanglement monotone. Here we derive finite-temperature equilibrium relations between Rényi moments of the NEE, and multipoint charge correlations. These relations are exemplified in quantum dot systems where the desired charge correlations can be measured via a nearby quantum point contact. In quantum dots recently realizing the multichannel Kondo effect we show that the NEE has a nontrivial universal temperature dependence which is now accessible using the proposed methods.
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Affiliation(s)
- Cheolhee Han
- School of Physics and Astronomy, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Yigal Meir
- Department of Physics, Ben-Gurion University of the Negev, Beer-Sheva, 84105 Israel
- Department of Physics, Princeton University, Princeton, New Jersey 08540, USA
| | - Eran Sela
- School of Physics and Astronomy, Tel Aviv University, Tel Aviv 6997801, Israel
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12
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Rovny J, Yuan Z, Fitzpatrick M, Abdalla AI, Futamura L, Fox C, Cambria MC, Kolkowitz S, de Leon NP. Nanoscale covariance magnetometry with diamond quantum sensors. Science 2022; 378:1301-1305. [PMID: 36548408 DOI: 10.1126/science.ade9858] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Nitrogen vacancy (NV) centers in diamond are atom-scale defects that can be used to sense magnetic fields with high sensitivity and spatial resolution. Typically, the magnetic field is measured by averaging sequential measurements of single NV centers, or by spatial averaging over ensembles of many NV centers, which provides mean values that contain no nonlocal information about the relationship between two points separated in space or time. Here, we propose and implement a sensing modality whereby two or more NV centers are measured simultaneously, and we extract temporal and spatial correlations in their signals that would otherwise be inaccessible. We demonstrate measurements of correlated applied noise using spin-to-charge readout of two NV centers and implement a spectral reconstruction protocol for disentangling local and nonlocal noise sources.
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Affiliation(s)
- Jared Rovny
- Department of Electrical and Computer Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Zhiyang Yuan
- Department of Electrical and Computer Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Mattias Fitzpatrick
- Department of Electrical and Computer Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Ahmed I Abdalla
- Department of Electrical and Computer Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Laura Futamura
- Department of Electrical and Computer Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Carter Fox
- Department of Physics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | | | - Shimon Kolkowitz
- Department of Physics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Nathalie P de Leon
- Department of Electrical and Computer Engineering, Princeton University, Princeton, NJ 08544, USA
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13
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Pan X, Zhou Y, Yuan H, Nie L, Wei W, Zhang L, Li J, Liu S, Jiang ZH, Catelani G, Hu L, Yan F, Yu D. Engineering superconducting qubits to reduce quasiparticles and charge noise. Nat Commun 2022; 13:7196. [PMID: 36418286 PMCID: PMC9684549 DOI: 10.1038/s41467-022-34727-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 11/02/2022] [Indexed: 11/25/2022] Open
Abstract
Identifying, quantifying, and suppressing decoherence mechanisms in qubits are important steps towards the goal of engineering a quantum computer or simulator. Superconducting circuits offer flexibility in qubit design; however, their performance is adversely affected by quasiparticles (broken Cooper pairs). Developing a quasiparticle mitigation strategy compatible with scalable, high-coherence devices is therefore highly desirable. Here we experimentally demonstrate how to control quasiparticle generation by downsizing the qubit, capping it with a metallic cover, and equipping it with suitable quasiparticle traps. Using a flip-chip design, we shape the electromagnetic environment of the qubit above the superconducting gap, inhibiting quasiparticle poisoning. Our findings support the hypothesis that quasiparticle generation is dominated by the breaking of Cooper pairs at the junction, as a result of photon absorption by the antenna-like qubit structure. We achieve record low charge-parity switching rate (<1 Hz). Our aluminium devices also display improved stability with respect to discrete charging events.
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Affiliation(s)
- Xianchuang Pan
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China.,International Quantum Academy, Shenzhen, Guangdong, China.,Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Yuxuan Zhou
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China.,International Quantum Academy, Shenzhen, Guangdong, China.,Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China.,Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Haolan Yuan
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China.,International Quantum Academy, Shenzhen, Guangdong, China.,Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China.,Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Lifu Nie
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China.,International Quantum Academy, Shenzhen, Guangdong, China.,Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Weiwei Wei
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China.,International Quantum Academy, Shenzhen, Guangdong, China.,Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Libo Zhang
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China.,International Quantum Academy, Shenzhen, Guangdong, China.,Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Jian Li
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China.,International Quantum Academy, Shenzhen, Guangdong, China.,Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Song Liu
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China.,International Quantum Academy, Shenzhen, Guangdong, China.,Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Zhi Hao Jiang
- State Key Laboratory of Millimeter Waves, School of Information Science and Engineering, Southeast University, Nanjing, China
| | - Gianluigi Catelani
- JARA Institute for Quantum Information (PGI-11), Forschungszentrum Jülich, 52425, Jülich, Germany. .,Quantum Research Centre, Technology Innovation Institute, Abu Dhabi, UAE.
| | - Ling Hu
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China. .,International Quantum Academy, Shenzhen, Guangdong, China. .,Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China.
| | - Fei Yan
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China. .,International Quantum Academy, Shenzhen, Guangdong, China. .,Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China.
| | - Dapeng Yu
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China.,International Quantum Academy, Shenzhen, Guangdong, China.,Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China.,Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong, China
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14
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Phonon downconversion to suppress correlated errors in superconducting qubits. Nat Commun 2022; 13:6425. [PMID: 36307415 DOI: 10.1038/s41467-022-33997-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 10/07/2022] [Indexed: 11/09/2022] Open
Abstract
Quantum error correction can preserve quantum information in the presence of local errors, but correlated errors are fatal. For superconducting qubits, high-energy particle impacts from background radioactivity produce energetic phonons that travel throughout the substrate and create excitations above the superconducting ground state, known as quasiparticles, which can poison all qubits on the chip. We use normal metal reservoirs on the chip back side to downconvert phonons to low energies where they can no longer poison qubits. We introduce a pump-probe scheme involving controlled injection of pair-breaking phonons into the qubit chips. We examine quasiparticle poisoning on chips with and without back-side metallization and demonstrate a reduction in the flux of pair-breaking phonons by over a factor of 20. We use a Ramsey interferometer scheme to simultaneously monitor quasiparticle parity on three qubits for each chip and observe a two-order of magnitude reduction in correlated poisoning due to background radiation.
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15
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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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16
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Ryu H, Kang JH. Devitalizing noise-driven instability of entangling logic in silicon devices with bias controls. Sci Rep 2022; 12:15200. [PMID: 36071130 PMCID: PMC9452571 DOI: 10.1038/s41598-022-19404-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 08/29/2022] [Indexed: 11/20/2022] Open
Abstract
The quality of quantum bits (qubits) in silicon is highly vulnerable to charge noise that is omnipresent in semiconductor devices and is in principle hard to be suppressed. For a realistically sized quantum dot system based on a silicon-germanium heterostructure whose confinement is manipulated with electrical biases imposed on top electrodes, we computationally explore the noise-robustness of 2-qubit entangling operations with a focus on the controlled-X (CNOT) logic that is essential for designs of gate-based universal quantum logic circuits. With device simulations based on the physics of bulk semiconductors augmented with electronic structure calculations, we not only quantify the degradation in fidelity of single-step CNOT operations with respect to the strength of charge noise, but also discuss a strategy of device engineering that can significantly enhance noise-robustness of CNOT operations with almost no sacrifice of speed compared to the single-step case. Details of device designs and controls that this work presents can establish practical guideline for potential efforts to secure silicon-based quantum processors using an electrode-driven quantum dot platform.
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Affiliation(s)
- Hoon Ryu
- Korea Institute of Science and Technology Information, Daejeon, 34141, Republic of Korea.
| | - Ji-Hoon Kang
- Korea Institute of Science and Technology Information, Daejeon, 34141, Republic of Korea
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17
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Muniandy SV, Ishak NI, Yi CW. Entropy fluctuation and correlation transfer in tunable discrete-time quantum walk with fractional Gaussian noise. Phys Rev E 2022; 106:024113. [PMID: 36109886 DOI: 10.1103/physreve.106.024113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 07/26/2022] [Indexed: 06/15/2023]
Abstract
We study the time correlation in the von Neumann entropy fluctuation of the tunable discrete-time quantum walk in one dimension, induced by the coin disorder arising from the temporal fractional Gaussian noise (fGn). The fGn is characterized by the Hurst exponent H, which provides three different correlation scenarios, namely antipersistent (0<H<0.5), memoryless (H=0.5), and persistent (0.5<H<1). We show the correlation of fGn is transferred to the coin's degree of entanglement and eventually transpires in the time correlation of the von Neumann entropy fluctuation. This study hints at the potential of using noise correlation as a resource to sustain information backflow via the interaction of quantum system with the noisy environment.
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Affiliation(s)
- S V Muniandy
- Center for Theoretical and Computational Physics, Department of Physics, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia
| | - Nur Izzati Ishak
- Center for Theoretical and Computational Physics, Department of Physics, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia
| | - Chong Wu Yi
- Photonics Research Centre, University of Malaya, Kuala Lumpur 50603, Malaysia
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18
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Islam S, Shamim S, Ghosh A. Benchmarking Noise and Dephasing in Emerging Electrical Materials for Quantum Technologies. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022:e2109671. [PMID: 35545231 DOI: 10.1002/adma.202109671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 05/01/2022] [Indexed: 06/15/2023]
Abstract
As quantum technologies develop, a specific class of electrically conducting materials is rapidly gaining interest because they not only form the core quantum-enabled elements in superconducting qubits, semiconductor nanostructures, or sensing devices, but also the peripheral circuitry. The phase coherence of the electronic wave function in these emerging materials will be crucial when incorporated in the quantum architecture. The loss of phase memory, or dephasing, occurs when a quantum system interacts with the fluctuations in the local electromagnetic environment, which manifests in "noise" in the electrical conductivity. Hence, characterizing these materials and devices therefrom, for quantum applications, requires evaluation of both dephasing and noise, although there are very few materials where these properties are investigated simultaneously. Here, the available data on magnetotransport and low-frequency fluctuations in electrical conductivity are reviewed to benchmark the dephasing and noise. The focus is on new materials that are of direct interest to quantum technologies. The physical processes causing dephasing and noise in these systems are elaborated, the impact of both intrinsic and extrinsic parameters from materials synthesis and devices realization are evaluated, and it is hoped that a clearer pathway to design and characterize both material and devices for quantum applications is thus provided.
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Affiliation(s)
- Saurav Islam
- Department of Physics, Indian Institute of Science, Bengaluru, 560012, India
| | - Saquib Shamim
- Experimentelle Physik III, Physikalisches Institut, Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
- Institute for Topological Insulators, Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Arindam Ghosh
- Department of Physics, Indian Institute of Science, Bengaluru, 560012, India
- Centre for Nano Science and Engineering, Indian Institute of Science, Bengaluru, 560012, India
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19
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Spring PA, Cao S, Tsunoda T, Campanaro G, Fasciati S, Wills J, Bakr M, Chidambaram V, Shteynas B, Carpenter L, Gow P, Gates J, Vlastakis B, Leek PJ. High coherence and low cross-talk in a tileable 3D integrated superconducting circuit architecture. SCIENCE ADVANCES 2022; 8:eabl6698. [PMID: 35452292 PMCID: PMC9032975 DOI: 10.1126/sciadv.abl6698] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 03/07/2022] [Indexed: 06/14/2023]
Abstract
We report high qubit coherence as well as low cross-talk and single-qubit gate errors in a superconducting circuit architecture that promises to be tileable to two-dimensional (2D) lattices of qubits. The architecture integrates an inductively shunted cavity enclosure into a design featuring nongalvanic out-of-plane control wiring and qubits and resonators fabricated on opposing sides of a substrate. The proof-of-principle device features four uncoupled transmon qubits and exhibits average energy relaxation times T1 = 149(38) μs, pure echoed dephasing times Tϕ,e = 189(34) μs, and single-qubit gate fidelities F = 99.982(4)% as measured by simultaneous randomized benchmarking. The 3D integrated nature of the control wiring means that qubits will remain addressable as the architecture is tiled to form larger qubit lattices. Band structure simulations are used to predict that the tiled enclosure will still provide a clean electromagnetic environment to enclosed qubits at arbitrary scale.
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Affiliation(s)
- Peter A. Spring
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Shuxiang Cao
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Takahiro Tsunoda
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Giulio Campanaro
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Simone Fasciati
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - James Wills
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Mustafa Bakr
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Vivek Chidambaram
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Boris Shteynas
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Lewis Carpenter
- Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK
| | - Paul Gow
- Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK
| | - James Gates
- Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK
| | - Brian Vlastakis
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Peter J. Leek
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
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20
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Vepsäläinen A, Winik R, Karamlou AH, Braumüller J, Paolo AD, Sung Y, Kannan B, Kjaergaard M, Kim DK, Melville AJ, Niedzielski BM, Yoder JL, Gustavsson S, Oliver WD. Improving qubit coherence using closed-loop feedback. Nat Commun 2022; 13:1932. [PMID: 35410327 PMCID: PMC9001732 DOI: 10.1038/s41467-022-29287-4] [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: 05/17/2021] [Accepted: 02/24/2022] [Indexed: 11/09/2022] Open
Abstract
Superconducting qubits are a promising platform for building a larger-scale quantum processor capable of solving otherwise intractable problems. In order for the processor to reach practical viability, the gate errors need to be further suppressed and remain stable for extended periods of time. With recent advances in qubit control, both single- and two-qubit gate fidelities are now in many cases limited by the coherence times of the qubits. Here we experimentally employ closed-loop feedback to stabilize the frequency fluctuations of a superconducting transmon qubit, thereby increasing its coherence time by 26% and reducing the single-qubit error rate from (8.5 ± 2.1) × 10−4 to (5.9 ± 0.7) × 10−4. Importantly, the resulting high-fidelity operation remains effective even away from the qubit flux-noise insensitive point, significantly increasing the frequency bandwidth over which the qubit can be operated with high fidelity. This approach is helpful in large qubit grids, where frequency crowding and parasitic interactions between the qubits limit their performance. The presence of various noises in the qubit environment is a major limitation on qubit coherence time. Here, the authors demonstrate the use a closed-loop feedback to stabilize frequency noise in a flux-tunable superconducting qubit and suggest this as a scalable approach applicable to other types of noise.
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21
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Search for Majorana neutrinos exploiting millikelvin cryogenics with CUORE. Nature 2022; 604:53-58. [PMID: 35388194 PMCID: PMC8986534 DOI: 10.1038/s41586-022-04497-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 02/01/2022] [Indexed: 11/16/2022]
Abstract
The possibility that neutrinos may be their own antiparticles, unique among the known fundamental particles, arises from the symmetric theory of fermions proposed by Ettore Majorana in 19371. Given the profound consequences of such Majorana neutrinos, among which is a potential explanation for the matter–antimatter asymmetry of the universe via leptogenesis2, the Majorana nature of neutrinos commands intense experimental scrutiny globally; one of the primary experimental probes is neutrinoless double beta (0νββ) decay. Here we show results from the search for 0νββ decay of 130Te, using the latest advanced cryogenic calorimeters with the CUORE experiment3. CUORE, operating just 10 millikelvin above absolute zero, has pushed the state of the art on three frontiers: the sheer mass held at such ultralow temperatures, operational longevity, and the low levels of ionizing radiation emanating from the cryogenic infrastructure. We find no evidence for 0νββ decay and set a lower bound of the process half-life as 2.2 × 1025 years at a 90 per cent credibility interval. We discuss potential applications of the advances made with CUORE to other fields such as direct dark matter, neutrino and nuclear physics searches and large-scale quantum computing, which can benefit from sustained operation of large payloads in a low-radioactivity, ultralow-temperature cryogenic environment. The CUORE experiment finds no evidence for neutrinoless double beta decay after operating a large cryogenic TeO2 calorimeter stably for several years in an extreme low-radiation environment at a temperature of 10 millikelvin.
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22
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Seif A, Wang YX, Clerk AA. Distinguishing between Quantum and Classical Markovian Dephasing Dissipation. PHYSICAL REVIEW LETTERS 2022; 128:070402. [PMID: 35244435 DOI: 10.1103/physrevlett.128.070402] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 12/09/2021] [Accepted: 01/20/2022] [Indexed: 06/14/2023]
Abstract
Understanding whether dissipation in an open quantum system is truly quantum is a question of both fundamental and practical interest. We consider n qubits subject to correlated Markovian dephasing and present a sufficient condition for when bath-induced dissipation can generate system entanglement and hence must be considered quantum. Surprisingly, we find that the presence or absence of time-reversal symmetry plays a crucial role: broken time-reversal symmetry is required for dissipative entanglement generation. Further, simply having nonzero bath susceptibilities is not enough for the dissipation to be quantum. We also present an explicit experimental protocol for identifying truly quantum dephasing dissipation and lay the groundwork for studying more complex dissipative systems and finding optimal noise mitigating strategies.
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Affiliation(s)
- Alireza Seif
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| | - Yu-Xin Wang
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| | - Aashish A Clerk
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
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23
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Hirota O. Introduction to Semi-Classical Analysis for Digital Errors of Qubit in Quantum Processor. ENTROPY 2021; 23:e23121577. [PMID: 34945882 PMCID: PMC8700742 DOI: 10.3390/e23121577] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 11/23/2021] [Accepted: 11/23/2021] [Indexed: 11/22/2022]
Abstract
In recent years, remarkable progress has been achieved in the development of quantum computers. For further development, it is important to clarify properties of errors by quantum noise and environment noise. However, when the system scale of quantum processors is expanded, it has been pointed out that a new type of quantum error, such as nonlinear error, appears. It is not clear how to handle such new effects in information theory. First of all, one should make the characteristics of the error probability of qubits clear as communication channel error models in information theory. The purpose of this paper is to survey the progress for modeling the quantum noise effects that information theorists are likely to face in the future, to cope with such nontrivial errors mentioned above. This paper explains a channel error model to represent strange properties of error probability due to new quantum noise. By this model, specific examples on the features of error probability caused by, for example, quantum recurrence effects, collective relaxation, and external force, are given. As a result, it is possible to understand the meaning of strange features of error probability that do not exist in classical information theory without going through complex physical phenomena.
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Affiliation(s)
- Osamu Hirota
- Quantum ICT Research Institute, Tamagawa University, Tokyo 194-8610, Japan;
- Reserch and Development Initiative, Chuo University, Tokyo 112-8551, Japan
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24
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Intrinsic and induced quantum quenches for enhancing qubit-based quantum noise spectroscopy. Nat Commun 2021; 12:6528. [PMID: 34764276 PMCID: PMC8586144 DOI: 10.1038/s41467-021-26868-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 10/26/2021] [Indexed: 11/18/2022] Open
Abstract
Quantum sensing protocols that exploit the dephasing of a probe qubit are powerful and ubiquitous methods for interrogating an unknown environment. They have a variety of applications, ranging from noise mitigation in quantum processors, to the study of correlated electron states. Here, we discuss a simple strategy for enhancing these methods, based on the fact that they often give rise to an inadvertent quench of the probed system: there is an effective sudden change in the environmental Hamiltonian at the start of the sensing protocol. These quenches are extremely sensitive to the initial environmental state, and lead to observable changes in the sensor qubit evolution. We show how these new features give access to environmental response properties. This enables methods for direct measurement of bath temperature, and for detecting non-thermal equilibrium states. We also discuss how to deliberately control and modulate this quench physics, which enables reconstruction of the bath spectral function. Extensions to non-Gaussian quantum baths are also discussed, as is the application of our ideas to a range of sensing platforms (e.g., nitrogen-vacancy (NV) centers in diamond, semiconductor quantum dots, and superconducting circuits).
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25
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Mannila ET, Maisi VF, Pekola JP. Self-Calibrating Superconducting Pair-Breaking Detector. PHYSICAL REVIEW LETTERS 2021; 127:147001. [PMID: 34652173 DOI: 10.1103/physrevlett.127.147001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 06/23/2021] [Accepted: 08/06/2021] [Indexed: 06/13/2023]
Abstract
We propose and experimentally demonstrate a self-calibrating detector of Cooper pair depairing in a superconductor based on a mesoscopic superconducting island coupled to normal metal leads. On average, exactly one electron passes through the device per broken Cooper pair, independent of the absorber volume, device, or material parameters. The device operation is explained by a simple analytical model and verified with numerical simulations in quantitative agreement with experiment. In a proof-of-concept experiment, we use such a detector to measure the high-frequency phonons generated by another, electrically decoupled superconducting island, with a measurable signal resulting from less than 10 fW of dissipated power.
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Affiliation(s)
- E T Mannila
- QTF Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland
| | - V F Maisi
- Physics Department and NanoLund, Lund University, Box 118, 22100 Lund, Sweden
| | - J P Pekola
- QTF Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland
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