1
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Fallek SD, Sandhu VS, McGill RA, Gray JM, Tinkey HN, Clark CR, Brown KR. Rapid exchange cooling with trapped ions. Nat Commun 2024; 15:1089. [PMID: 38316766 PMCID: PMC11258264 DOI: 10.1038/s41467-024-45232-z] [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: 09/22/2023] [Accepted: 01/18/2024] [Indexed: 02/07/2024] Open
Abstract
The trapped-ion quantum charge-coupled device (QCCD) architecture is a leading candidate for advanced quantum information processing. In current QCCD implementations, imperfect ion transport and anomalous heating can excite ion motion during a calculation. To counteract this, intermediate cooling is necessary to maintain high-fidelity gate performance. Cooling the computational ions sympathetically with ions of another species, a commonly employed strategy, creates a significant runtime bottleneck. Here, we demonstrate a different approach we call exchange cooling. Unlike sympathetic cooling, exchange cooling does not require trapping two different atomic species. The protocol introduces a bank of "coolant" ions which are repeatedly laser cooled. A computational ion can then be cooled by transporting a coolant ion into its proximity. We test this concept experimentally with two 40Ca+ ions, executing the necessary transport in 107 μs, an order of magnitude faster than typical sympathetic cooling durations. We remove over 96%, and as many as 102(5) quanta, of axial motional energy from the computational ion. We verify that re-cooling the coolant ion does not decohere the computational ion. This approach validates the feasibility of a single-species QCCD processor, capable of fast quantum simulation and computation.
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Affiliation(s)
| | | | - Ryan A McGill
- Georgia Tech Research Institute, Atlanta, 30332, GA, USA
| | - John M Gray
- Georgia Tech Research Institute, Atlanta, 30332, GA, USA
| | - Holly N Tinkey
- Georgia Tech Research Institute, Atlanta, 30332, GA, USA
| | - Craig R Clark
- Georgia Tech Research Institute, Atlanta, 30332, GA, USA
| | - Kenton R Brown
- Georgia Tech Research Institute, Atlanta, 30332, GA, USA
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2
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Srinivas R, Löschnauer CM, Malinowski M, Hughes AC, Nourshargh R, Negnevitsky V, Allcock DTC, King SA, Matthiesen C, Harty TP, Ballance CJ. Coherent Control of Trapped-Ion Qubits with Localized Electric Fields. PHYSICAL REVIEW LETTERS 2023; 131:020601. [PMID: 37505962 DOI: 10.1103/physrevlett.131.020601] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 05/23/2023] [Indexed: 07/30/2023]
Abstract
We present a new method for coherent control of trapped ion qubits in separate interaction regions of a multizone trap by simultaneously applying an electric field and a spin-dependent gradient. Both the phase and amplitude of the effective single-qubit rotation depend on the electric field, which can be localized to each zone. We demonstrate this interaction on a single ion using both laser-based and magnetic-field gradients in a surface-electrode ion trap, and measure the localization of the electric field.
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Affiliation(s)
- R Srinivas
- Oxford Ionics, Oxford, OX5 1PF, United Kingdom
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, United Kingdom
| | | | | | - A C Hughes
- Oxford Ionics, Oxford, OX5 1PF, United Kingdom
| | | | | | - D T C Allcock
- Oxford Ionics, Oxford, OX5 1PF, United Kingdom
- Department of Physics, University of Oregon, Eugene, Oregon 97403, USA
| | - S A King
- Oxford Ionics, Oxford, OX5 1PF, United Kingdom
| | | | - T P Harty
- Oxford Ionics, Oxford, OX5 1PF, United Kingdom
| | - C J Ballance
- Oxford Ionics, Oxford, OX5 1PF, United Kingdom
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, United Kingdom
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3
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Akhtar M, Bonus F, Lebrun-Gallagher FR, Johnson NI, Siegele-Brown M, Hong S, Hile SJ, Kulmiya SA, Weidt S, Hensinger WK. A high-fidelity quantum matter-link between ion-trap microchip modules. Nat Commun 2023; 14:531. [PMID: 36754957 PMCID: PMC9908934 DOI: 10.1038/s41467-022-35285-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 11/25/2022] [Indexed: 02/10/2023] Open
Abstract
System scalability is fundamental for large-scale quantum computers (QCs) and is being pursued over a variety of hardware platforms. For QCs based on trapped ions, architectures such as the quantum charge-coupled device (QCCD) are used to scale the number of qubits on a single device. However, the number of ions that can be hosted on a single quantum computing module is limited by the size of the chip being used. Therefore, a modular approach is of critical importance and requires quantum connections between individual modules. Here, we present the demonstration of a quantum matter-link in which ion qubits are transferred between adjacent QC modules. Ion transport between adjacent modules is realised at a rate of 2424 s-1 and with an infidelity associated with ion loss during transport below 7 × 10-8. Furthermore, we show that the link does not measurably impact the phase coherence of the qubit. The quantum matter-link constitutes a practical mechanism for the interconnection of QCCD devices. Our work will facilitate the implementation of modular QCs capable of fault-tolerant utility-scale quantum computation.
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Affiliation(s)
- M. Akhtar
- grid.12082.390000 0004 1936 7590Sussex Centre for Quantum Technologies, University of Sussex, Brighton, BN1 9QH UK ,Universal Quantum Ltd, Brighton, BN1 6SB UK
| | - F. Bonus
- Universal Quantum Ltd, Brighton, BN1 6SB UK ,grid.83440.3b0000000121901201Department of Physics and Astronomy, University College London, London, WC1E 6BT UK
| | - F. R. Lebrun-Gallagher
- grid.12082.390000 0004 1936 7590Sussex Centre for Quantum Technologies, University of Sussex, Brighton, BN1 9QH UK ,Universal Quantum Ltd, Brighton, BN1 6SB UK
| | - N. I. Johnson
- grid.12082.390000 0004 1936 7590Sussex Centre for Quantum Technologies, University of Sussex, Brighton, BN1 9QH UK
| | - M. Siegele-Brown
- grid.12082.390000 0004 1936 7590Sussex Centre for Quantum Technologies, University of Sussex, Brighton, BN1 9QH UK
| | - S. Hong
- grid.12082.390000 0004 1936 7590Sussex Centre for Quantum Technologies, University of Sussex, Brighton, BN1 9QH UK
| | - S. J. Hile
- grid.12082.390000 0004 1936 7590Sussex Centre for Quantum Technologies, University of Sussex, Brighton, BN1 9QH UK
| | - S. A. Kulmiya
- grid.12082.390000 0004 1936 7590Sussex Centre for Quantum Technologies, University of Sussex, Brighton, BN1 9QH UK ,grid.5337.20000 0004 1936 7603Quantum Engineering Centre for Doctoral Training, University of Bristol, Bristol, BS8 1TH UK
| | - S. Weidt
- grid.12082.390000 0004 1936 7590Sussex Centre for Quantum Technologies, University of Sussex, Brighton, BN1 9QH UK ,Universal Quantum Ltd, Brighton, BN1 6SB UK
| | - W. K. Hensinger
- grid.12082.390000 0004 1936 7590Sussex Centre for Quantum Technologies, University of Sussex, Brighton, BN1 9QH UK ,Universal Quantum Ltd, Brighton, BN1 6SB UK
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4
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Espinós H, Echanobe J, Lu XJ, Muga JG. Fast ion shuttling which is robust versus oscillatory perturbations. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2022; 380:20210269. [PMID: 36335938 DOI: 10.1098/rsta.2021.0269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 12/13/2021] [Indexed: 06/16/2023]
Abstract
Shuttling protocols designed by shortcut-to-adiabaticity techniques may suffer from perturbations and imperfect implementations. We study the motional excitation of a single ion shuttled in harmonic traps with time-dependent, 'systematic' oscillatory perturbations around the nominal parameters. These elementary perturbations could form any other by superposition. Robust shuttling strategies are proposed and compared, and optimizations are performed. This article is part of the theme issue 'Shortcuts to adiabaticity: theoretical, experimental and interdisciplinary perspectives'.
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Affiliation(s)
- H Espinós
- Department of Physical Chemistry, University of the Basque Country UPV/EHU, Apdo 644, Bilbao, Spain
| | - J Echanobe
- Departamento de Electricidad y Electrónica, UPV/EHU, Apdo 644, Bilbao, Spain
| | - X-J Lu
- School of Electric and Mechatronics Engineering, Xuchang University, Xuchang 461000, People's Republic of China
| | - J G Muga
- Department of Physical Chemistry, University of the Basque Country UPV/EHU, Apdo 644, Bilbao, Spain
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5
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Li J, Chen X, Ruschhaupt A. Fast transport of Bose-Einstein condensates in anharmonic traps. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2022; 380:20210280. [PMID: 36335948 PMCID: PMC9653254 DOI: 10.1098/rsta.2021.0280] [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: 07/11/2022] [Accepted: 09/20/2022] [Indexed: 06/16/2023]
Abstract
We present a method to transport Bose-Einstein condensates (BECs) in anharmonic traps and in the presence of atom-atom interactions in short times without residual excitation. Using a combination of a variational approach and inverse engineering methods, we derive a set of Ermakov-like equations that take into account the coupling between the centre of mass motion and the breathing mode. By an appropriate inverse engineering strategy of those equations, we then design the trap trajectory to achieve the desired boundary conditions. Numerical examples for cubic or quartic anharmonicities are provided for fast and high-fidelity transport of BECs. Potential applications are atom interferometry and quantum information processing. This article is part of the theme issue 'Shortcuts to adiabaticity: theoretical, experimental and interdisciplinary perspectives'.
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Affiliation(s)
- Jing Li
- Department of Physics, University College Cork, Cork, T12 H6T1 Ireland
| | - Xi Chen
- Department of Physical Chemistry, University of the Basque Country UPV/EHU, Apartado 644, 48080 Bilbao, Spain
- EHU Quantum Center, University of the Basque Country UPV/EHU, 48940 Leioa, Spain
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6
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Masuda S, Nakamura K. Fast-forward scaling theory. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2022; 380:20210278. [PMID: 36335946 PMCID: PMC9653242 DOI: 10.1098/rsta.2021.0278] [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: 04/27/2022] [Accepted: 05/12/2022] [Indexed: 06/16/2023]
Abstract
Speed is the key to further advances in technology. For example, quantum technologies, such as quantum computing, require fast manipulations of quantum systems in order to overcome the effect of decoherence. However, controlling the speed of quantum dynamics is often very difficult due to both the lack of a simple scaling property in the dynamics and the infinitely large parameter space to be explored. Therefore, protocols for speed control based on understanding of the dynamical properties of the system, such as non-trivial scaling property, are highly desirable. Fast-forward scaling theory (FFST) was originally developed to provide a way to accelerate, decelerate, stop and reverse the dynamics of quantum systems. FFST has been extended in order to accelerate quantum and classical adiabatic dynamics of various systems including cold atoms, internal state of molecules, spins and solid-state artificial atoms. This paper describes the basic concept of FFST and reviews the recent developments and its applications such as fast state-preparations, state protection and ion sorting. We introduce a method, called inter-trajectory travel, recently derived from FFST. We also point out the significance of deceleration in quantum technology. This article is part of the theme issue 'Shortcuts to adiabaticity: theoretical, experimental and interdisciplinary perspectives'.
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Affiliation(s)
- S. Masuda
- Research Center for Emerging Computing Technologies (RCECT), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - K. Nakamura
- Faculty of Physics, National University of Uzbekistan, Vuzgorodok, Tashkent 100174, Uzbekistan
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7
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A space-based quantum gas laboratory at picokelvin energy scales. Nat Commun 2022; 13:7889. [PMID: 36550117 PMCID: PMC9780313 DOI: 10.1038/s41467-022-35274-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Accepted: 11/17/2022] [Indexed: 12/24/2022] Open
Abstract
Ultracold quantum gases are ideal sources for high-precision space-borne sensing as proposed for Earth observation, relativistic geodesy and tests of fundamental physical laws as well as for studying new phenomena in many-body physics during extended free fall. Here we report on experiments with the Cold Atom Lab aboard the International Space Station, where we have achieved exquisite control over the quantum state of single 87Rb Bose-Einstein condensates paving the way for future high-precision measurements. In particular, we have applied fast transport protocols to shuttle the atomic cloud over a millimeter distance with sub-micrometer accuracy and subsequently drastically reduced the total expansion energy to below 100 pK with matter-wave lensing techniques.
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8
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Soriani A, Miranda E, Deffner S, Bonança MVS. Shortcuts to Thermodynamic Quasistaticity. PHYSICAL REVIEW LETTERS 2022; 129:170602. [PMID: 36332265 DOI: 10.1103/physrevlett.129.170602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 09/16/2022] [Accepted: 09/22/2022] [Indexed: 06/16/2023]
Abstract
The operation of near-term quantum technologies requires the development of feasible, implementable, and robust strategies of controlling complex many body systems. To this end, a variety of techniques, so-called "shortcuts to adiabaticity," have been developed. Many of these shortcuts have already been demonstrated to be powerful and implementable in distinct scenarios. Yet, it is often also desirable to have additional, approximate strategies available that are applicable to a large class of systems. Hence, in this Letter, we take inspiration from thermodynamics and propose to focus on the macrostate, rather than the microstate. Adiabatic dynamics can then be identified as such processes that preserve the equation of state, and systematic corrections are obtained from adiabatic perturbation theory. We demonstrate this approach by improving upon fast quasiadiabatic driving, and by applying the method to the quantum Ising chain in the transverse field.
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Affiliation(s)
- Artur Soriani
- Gleb Wataghin Institute of Physics, University of Campinas, Campinas, São Paulo 13083-950, Brazil
| | - Eduardo Miranda
- Gleb Wataghin Institute of Physics, University of Campinas, Campinas, São Paulo 13083-950, Brazil
| | - Sebastian Deffner
- Department of Physics, University of Maryland, Baltimore County, Baltimore, Maryland 21250, USA
| | - Marcus V S Bonança
- Gleb Wataghin Institute of Physics, University of Campinas, Campinas, São Paulo 13083-950, Brazil
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9
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Tinkey HN, Clark CR, Sawyer BC, Brown KR. Transport-Enabled Entangling Gate for Trapped Ions. PHYSICAL REVIEW LETTERS 2022; 128:050502. [PMID: 35179924 DOI: 10.1103/physrevlett.128.050502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 01/07/2022] [Indexed: 06/14/2023]
Abstract
We implement a 2-qubit entangling Mølmer-Sørensen interaction by transporting two cotrapped ^{40}Ca^{+} ions through a stationary, bichromatic optical beam within a surface-electrode Paul trap. We describe a procedure for achieving a constant Doppler shift during the transport, which uses fine temporal adjustment of the moving confinement potential. The fixed interaction duration of the ions transported through the laser beam as well as the dynamically changing ac Stark shift require alterations to the calibration procedures used for a stationary gate. We use the interaction to produce Bell states with fidelities commensurate to those of stationary gates performed in the same system. This result establishes the feasibility of actively incorporating ion transport into quantum information entangling operations.
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Affiliation(s)
- Holly N Tinkey
- Georgia Tech Research Institute, Atlanta, Georgia 30332, USA
| | - Craig R Clark
- Georgia Tech Research Institute, Atlanta, Georgia 30332, USA
| | - Brian C Sawyer
- Georgia Tech Research Institute, Atlanta, Georgia 30332, USA
| | - Kenton R Brown
- Georgia Tech Research Institute, Atlanta, Georgia 30332, USA
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10
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Sutherland RT, Burd SC, Slichter DH, Libby SB, Leibfried D. Motional Squeezing for Trapped Ion Transport and Separation. PHYSICAL REVIEW LETTERS 2021; 127:083201. [PMID: 34477447 PMCID: PMC10545415 DOI: 10.1103/physrevlett.127.083201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 07/19/2021] [Indexed: 06/13/2023]
Abstract
Transport, separation, and merging of trapped ion crystals are essential operations for most large-scale quantum computing architectures. In this Letter, we develop a theoretical framework that describes the dynamics of ions in time-varying potentials with a motional squeeze operator, followed by a motional displacement operator. Using this framework, we develop a new, general protocol for trapped ion transport, separation, and merging. We show that motional squeezing can prepare an ion wave packet to enable transfer from the ground state of one trapping potential to another. The framework and protocol are applicable if the potential is harmonic over the extent of the ion wave packets at all times. As illustrations, we discuss two specific operations: changing the strength of the confining potential for a single ion and separating same-species ions with their mutual Coulomb force. Both of these operations are, ideally, free of residual motional excitation.
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Affiliation(s)
- R. T. Sutherland
- Department of Electrical and Computer Engineering, University of Texas at San Antonio, San Antonio, Texas 78249, USA
| | - S. C. Burd
- Time and Frequency Division, National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - D. H. Slichter
- Time and Frequency Division, National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - S. B. Libby
- Physics Division, Physical and Life Sciences, Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - D. Leibfried
- Time and Frequency Division, National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
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11
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Kolbow JD, Lindquist NC, Ertsgaard CT, Yoo D, Oh SH. Nano-Optical Tweezers: Methods and Applications for Trapping Single Molecules and Nanoparticles. Chemphyschem 2021; 22:1409-1420. [PMID: 33797179 DOI: 10.1002/cphc.202100004] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 03/31/2021] [Indexed: 11/10/2022]
Abstract
Optical tweezers were developed in 1970 by Arthur Ashkin as a tool for the manipulation of micron-sized particles. Ashkin's original design was then adapted for a variety of purposes, such as trapping and manipulation of biological materials[1] and the laser cooling of atoms.[2,3] More recent development has led to nano-optical tweezers, for trapping particles on the scale of only a few nanometers, and holographic tweezers, which allow for dynamic control of multiple traps in real-time. These alternatives to conventional optical tweezers have made it possible to trap single molecules and to perform a variety of studies on them. Presented here is a review of recent developments in nano-optical tweezers and their current and future applications.
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Affiliation(s)
- Joshua D Kolbow
- Department of Electrical and Computer Engineering, University of Minnesota Kenneth H. Keller Hall, 200, Union St SE, Minneapolis, MN 55455, USA
| | - Nathan C Lindquist
- Department of Physics and Engineering, Bethel University, 3900 Bethel Drive, St. Paul, MN 55112, USA
| | - Christopher T Ertsgaard
- Department of Electrical and Computer Engineering, University of Minnesota Kenneth H. Keller Hall, 200, Union St SE, Minneapolis, MN 55455, USA
| | - Daehan Yoo
- Department of Electrical and Computer Engineering, University of Minnesota Kenneth H. Keller Hall, 200, Union St SE, Minneapolis, MN 55455, USA
| | - Sang-Hyun Oh
- Department of Electrical and Computer Engineering, University of Minnesota Kenneth H. Keller Hall, 200, Union St SE, Minneapolis, MN 55455, USA
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12
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Demonstration of the trapped-ion quantum CCD computer architecture. Nature 2021; 592:209-213. [PMID: 33828318 DOI: 10.1038/s41586-021-03318-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 02/01/2021] [Indexed: 02/01/2023]
Abstract
The trapped-ion quantum charge-coupled device (QCCD) proposal1,2 lays out a blueprint for a universal quantum computer that uses mobile ions as qubits. Analogous to a charge-coupled device (CCD) camera, which stores and processes imaging information as movable electrical charges in coupled pixels, a QCCD computer stores quantum information in the internal state of electrically charged ions that are transported between different processing zones using dynamic electric fields. The promise of the QCCD architecture is to maintain the low error rates demonstrated in small trapped-ion experiments3-5 by limiting the quantum interactions to multiple small ion crystals, then physically splitting and rearranging the constituent ions of these crystals into new crystals, where further interactions occur. This approach leverages transport timescales that are fast relative to the coherence times of the qubits, the insensitivity of the qubit states of the ion to the electric fields used for transport, and the low crosstalk afforded by spatially separated crystals. However, engineering a machine capable of executing these operations across multiple interaction zones with low error introduces many difficulties, which have slowed progress in scaling this architecture to larger qubit numbers. Here we use a cryogenic surface trap to integrate all necessary elements of the QCCD architecture-a scalable trap design, parallel interaction zones and fast ion transport-into a programmable trapped-ion quantum computer that has a system performance consistent with the low error rates achieved in the individual ion crystals. We apply this approach to realize a teleported CNOT gate using mid-circuit measurement6, negligible crosstalk error and a quantum volume7 of 26 = 64. These results demonstrate that the QCCD architecture provides a viable path towards high-performance quantum computers.
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13
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Connection between Inverse Engineering and Optimal Control in Shortcuts to Adiabaticity. ENTROPY 2021; 23:e23010084. [PMID: 33435274 PMCID: PMC7827842 DOI: 10.3390/e23010084] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 01/02/2021] [Accepted: 01/06/2021] [Indexed: 11/25/2022]
Abstract
We consider fast high-fidelity quantum control by using a shortcut to adiabaticity (STA) technique and optimal control theory (OCT). Three specific examples, including expansion of cold atoms from the harmonic trap, atomic transport by moving harmonic trap, and spin dynamics in the presence of dissipation, are explicitly detailed. Using OCT as a qualitative guide, we demonstrate how STA protocols designed from inverse engineering method can approach with very high precision optimal solutions built about physical constraints, by a proper choice of the interpolation function and with a very reduced number of adjustable parameters.
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14
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Zhu G, Lavasani A, Barkeshli M. Universal Logical Gates on Topologically Encoded Qubits via Constant-Depth Unitary Circuits. PHYSICAL REVIEW LETTERS 2020; 125:050502. [PMID: 32794843 DOI: 10.1103/physrevlett.125.050502] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 07/08/2020] [Indexed: 06/11/2023]
Abstract
A fundamental question in the theory of quantum computation is to understand the ultimate space-time resource costs for performing a universal set of logical quantum gates to arbitrary precision. Here we demonstrate that non-Abelian anyons in Turaev-Viro quantum error correcting codes can be moved over a distance of order of the code distance, and thus braided, by a constant depth local unitary quantum circuit followed by a permutation of qubits. Our gates are protected in the sense that the lengths of error strings do not grow by more than a constant factor. When applied to the Fibonacci code, our results demonstrate that a universal logical gate set can be implemented on encoded qubits through a constant depth unitary quantum circuit, and without increasing the asymptotic scaling of the space overhead. These results also apply directly to braiding of topological defects in surface codes. Our results reformulate the notion of braiding in general as an effectively instantaneous process, rather than as an adiabatic, slow process.
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Affiliation(s)
- Guanyu Zhu
- Department of Physics, Condensed Matter Theory Center, University of Maryland, College Park, Maryland 20742, USA and Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA
| | - Ali Lavasani
- Department of Physics, Condensed Matter Theory Center, University of Maryland, College Park, Maryland 20742, USA and Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA
| | - Maissam Barkeshli
- Department of Physics, Condensed Matter Theory Center, University of Maryland, College Park, Maryland 20742, USA and Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA
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15
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Impens F, Duboscq R, Guéry-Odelin D. Quantum Control beyond the Adiabatic Regime in 2D Curved Matter-Wave Guides. PHYSICAL REVIEW LETTERS 2020; 124:250403. [PMID: 32639754 DOI: 10.1103/physrevlett.124.250403] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 06/04/2020] [Indexed: 06/11/2023]
Abstract
The propagation of matter waves in curved geometry is relevant for ion transport, atomtronics and electrons in nanowires. Curvature effects are usually addressed within the adiabatic limit and treated via an effective potential acting on the manifold to which the particles are strongly confined. However, the strength of the confinements that can be achieved experimentally are limited in practice, and the adiabatic approximation often appears too restrictive for realistic guides. Here, we work out a design method for 2D sharply bent waveguides beyond this approximation using an exact inverse-engineering technique. The efficiency of the method is confirmed by the resolution of the 2D nonlinear Schrödinger equation in curved geometry. In this way, we realize reflectionless and ultrarobust curved guides, even in the presence of interactions. Here, the transverse stability is improved by several orders of magnitude when compared to circular guides of similar size.
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Affiliation(s)
- François Impens
- Instituto de Física, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-972, Brazil
| | - Romain Duboscq
- Université de Toulouse; CNRS, INSA IMT, F-31062 Toulouse Cedex 9, France
| | - David Guéry-Odelin
- Laboratoire Collisions, Agrégats, Réactivité, IRSAMC, Université de Toulouse, CNRS, UPS, F-31062 Toulouse Cedex 09, France
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16
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Stephenson LJ, Nadlinger DP, Nichol BC, An S, Drmota P, Ballance TG, Thirumalai K, Goodwin JF, Lucas DM, Ballance CJ. High-Rate, High-Fidelity Entanglement of Qubits Across an Elementary Quantum Network. PHYSICAL REVIEW LETTERS 2020; 124:110501. [PMID: 32242699 DOI: 10.1103/physrevlett.124.110501] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 02/06/2020] [Indexed: 06/11/2023]
Abstract
We demonstrate remote entanglement of trapped-ion qubits via a quantum-optical fiber link with fidelity and rate approaching those of local operations. Two ^{88}Sr^{+} qubits are entangled via the polarization degree of freedom of two spontaneously emitted 422 nm photons which are coupled by high-numerical-aperture lenses into single-mode optical fibers and interfere on a beam splitter. A novel geometry allows high-efficiency photon collection while maintaining unit fidelity for ion-photon entanglement. We generate heralded Bell pairs with fidelity 94% at an average rate 182 s^{-1} (success probability 2.18×10^{-4}).
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Affiliation(s)
- L J Stephenson
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - D P Nadlinger
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - B C Nichol
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - S An
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - P Drmota
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - T G Ballance
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - K Thirumalai
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - J F Goodwin
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - D M Lucas
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - C J Ballance
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
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17
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Invariant-Based Inverse Engineering for Fast and Robust Load Transport in a Double Pendulum Bridge Crane. ENTROPY 2020; 22:e22030350. [PMID: 33286124 PMCID: PMC7516821 DOI: 10.3390/e22030350] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 03/12/2020] [Accepted: 03/14/2020] [Indexed: 11/17/2022]
Abstract
We set a shortcut-to-adiabaticity strategy to design the trolley motion in a double-pendulum bridge crane. The trajectories found guarantee payload transport without residual excitation regardless of the initial conditions within the small oscillations regime. The results are compared with exact dynamics to set the working domain of the approach. The method is free from instabilities due to boundary effects or to resonances with the two natural frequencies.
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18
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19
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Lu XJ, Ruschhaupt A, Martínez-Garaot S, Muga JG. Noise Sensitivities for an Atom Shuttled by a Moving Optical Lattice via Shortcuts to Adiabaticity. ENTROPY 2020; 22:e22030262. [PMID: 33286036 PMCID: PMC7516713 DOI: 10.3390/e22030262] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 02/21/2020] [Accepted: 02/21/2020] [Indexed: 11/30/2022]
Abstract
We find the noise sensitivities (i.e., the quadratic terms of the energy with respect to the perturbation of the noise) of a particle shuttled by an optical lattice that moves according to a shortcut-to-adiabaticity transport protocol. Noises affecting different optical lattice parameters, trap depth, position, and lattice periodicity, are considered. We find generic expressions of the sensitivities for arbitrary noise spectra but focus on the white-noise limit as a basic reference, and on Ornstein–Uhlenbeck noise to account for the effect of non-zero correlation times.
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Affiliation(s)
- Xiao-Jing Lu
- School of Electric and Mechatronics Engineering, Xuchang University, Xuchang 461000, China;
| | | | - Sofía Martínez-Garaot
- Departamento de Química Física, UPV/EHU, Apdo 644, 48080 Bilbao, Spain;
- Correspondence:
| | - Juan Gonzalo Muga
- Departamento de Química Física, UPV/EHU, Apdo 644, 48080 Bilbao, Spain;
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20
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Vogel J, Li W, Mokhberi A, Lesanovsky I, Schmidt-Kaler F. Shuttling of Rydberg Ions for Fast Entangling Operations. PHYSICAL REVIEW LETTERS 2019; 123:153603. [PMID: 31702316 DOI: 10.1103/physrevlett.123.153603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Indexed: 06/10/2023]
Abstract
We introduce a scheme to entangle Rydberg ions in a linear ion crystal, using the high electric polarizability of the Rydberg electronic states in combination with mutual Coulomb coupling of ions that establishes common modes of motion. After laser initialization of ions to a superposition of ground and Rydberg states, the entanglement operation is driven purely by applying a voltage pulse that shuttles the ion crystal back and forth. This operation can achieve entanglement on a sub-μs timescale, more than 2 orders of magnitude faster than typical gate operations driven by continuous-wave lasers. Our analysis shows that the fidelity achieved with this protocol can exceed 99.9% with experimentally achievable parameters.
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Affiliation(s)
- J Vogel
- QUANTUM, Johannes Gutenberg-Universität Mainz, Staudinger Weg 7, 55128 Mainz, Germany
| | - W Li
- School of Physics and Astronomy, Nottingham NG7 2RD, United Kingdom
- Centre for the Mathematics and Theoretical Physics of Quantum Non-equilibrium Systems, Nottingham NG7 2RD, United Kingdom
| | - A Mokhberi
- QUANTUM, Johannes Gutenberg-Universität Mainz, Staudinger Weg 7, 55128 Mainz, Germany
| | - I Lesanovsky
- School of Physics and Astronomy, Nottingham NG7 2RD, United Kingdom
- Centre for the Mathematics and Theoretical Physics of Quantum Non-equilibrium Systems, Nottingham NG7 2RD, United Kingdom
- Institut für Theoretische Physik, Universität Tübingen, Auf der Morgenstelle 14, 72076 Tübingen, Germany
| | - F Schmidt-Kaler
- QUANTUM, Johannes Gutenberg-Universität Mainz, Staudinger Weg 7, 55128 Mainz, Germany
- Helmholtz-Institut Mainz, Staudinger Weg 18, 55128 Mainz, Germany
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21
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Claeys PW, Pandey M, Sels D, Polkovnikov A. Floquet-Engineering Counterdiabatic Protocols in Quantum Many-Body Systems. PHYSICAL REVIEW LETTERS 2019; 123:090602. [PMID: 31524451 DOI: 10.1103/physrevlett.123.090602] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 07/17/2019] [Indexed: 05/26/2023]
Abstract
Counterdiabatic (CD) driving presents a way of generating adiabatic dynamics at an arbitrary pace, where excitations due to nonadiabaticity are exactly compensated by adding an auxiliary driving term to the Hamiltonian. While this CD term is theoretically known and given by the adiabatic gauge potential, obtaining and implementing this potential in many-body systems is a formidable task, requiring knowledge of the spectral properties of the instantaneous Hamiltonians and control of highly nonlocal multibody interactions. We show how an approximate gauge potential can be systematically built up as a series of nested commutators, remaining well defined in the thermodynamic limit. Furthermore, the resulting CD driving protocols can be realized up to arbitrary order without leaving the available control space using tools from periodically driven (Floquet) systems. This is illustrated on few- and many-body quantum systems, where the resulting Floquet protocols significantly suppress dissipation and provide a drastic increase in fidelity.
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Affiliation(s)
- Pieter W Claeys
- Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA
| | - Mohit Pandey
- Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA
| | - Dries Sels
- Department of Physics, Harvard University, 17 Oxford Street, Cambridge, Massachusetts 02138, USA
- Theory of Quantum and Complex Systems, Universiteit Antwerpen, B-2610 Antwerpen, Belgium
| | - Anatoli Polkovnikov
- Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA
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22
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Wan Y, Kienzler D, Erickson SD, Mayer KH, Tan TR, Wu JJ, Vasconcelos HM, Glancy S, Knill E, Wineland DJ, Wilson AC, Leibfried D. Quantum gate teleportation between separated qubits in a trapped-ion processor. Science 2019; 364:875-878. [DOI: 10.1126/science.aaw9415] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 05/08/2019] [Indexed: 11/02/2022]
Affiliation(s)
- Yong Wan
- National Institute of Standards and Technology, Boulder, CO 80305, USA
- Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - Daniel Kienzler
- National Institute of Standards and Technology, Boulder, CO 80305, USA
- Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - Stephen D. Erickson
- National Institute of Standards and Technology, Boulder, CO 80305, USA
- Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - Karl H. Mayer
- National Institute of Standards and Technology, Boulder, CO 80305, USA
- Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - Ting Rei Tan
- National Institute of Standards and Technology, Boulder, CO 80305, USA
- Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - Jenny J. Wu
- National Institute of Standards and Technology, Boulder, CO 80305, USA
- Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - Hilma M. Vasconcelos
- National Institute of Standards and Technology, Boulder, CO 80305, USA
- Department of Physics, University of Colorado, Boulder, CO 80309, USA
- Departamento de Engenharia de Teleinformática, Universidade Federal do Ceará, Fortaleza, Ceará, 60440, Brazil
| | - Scott Glancy
- National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - Emanuel Knill
- National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - David J. Wineland
- National Institute of Standards and Technology, Boulder, CO 80305, USA
- Department of Physics, University of Colorado, Boulder, CO 80309, USA
- Department of Physics, University of Oregon, Eugene, OR 97403, USA
| | - Andrew C. Wilson
- National Institute of Standards and Technology, Boulder, CO 80305, USA
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23
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Abah O, Paternostro M. Shortcut-to-adiabaticity Otto engine: A twist to finite-time thermodynamics. Phys Rev E 2019; 99:022110. [PMID: 30934342 DOI: 10.1103/physreve.99.022110] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Indexed: 06/09/2023]
Abstract
We consider a finite-time Otto engine operating on a quantum harmonic oscillator and driven by shortcut-to-adiabaticity (STA) techniques to speed up its cycle. We study its efficiency and power when internal friction, time-averaged work, and work fluctuations are used as quantitative figures of merit, showing that time-averaged efficiency and power are useful cost functions for the characterization of the performance of the engine. We then use the minimum allowed time for validity of STA protocol relation to establish a physically relevant bound to the efficiency at maximum power of the STA-driven cycle.
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Affiliation(s)
- Obinna Abah
- Centre for Theoretical Atomic, Molecular and Optical Physics, Queen's University Belfast, Belfast BT7 1NN, United Kingdom
| | - Mauro Paternostro
- Centre for Theoretical Atomic, Molecular and Optical Physics, Queen's University Belfast, Belfast BT7 1NN, United Kingdom
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24
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Abstract
The control and manipulation of quantum systems without excitation are challenging, due to the complexities in fully modeling such systems accurately and the difficulties in controlling these inherently fragile systems experimentally. For example, while protocols to decompress Bose-Einstein condensates (BECs) faster than the adiabatic timescale (without excitation or loss) have been well developed theoretically, experimental implementations of these protocols have yet to reach speeds faster than the adiabatic timescale. In this work, we experimentally demonstrate an alternative approach based on a machine-learning algorithm which makes progress toward this goal. The algorithm is given control of the coupled decompression and transport of a metastable helium condensate, with its performance determined after each experimental iteration by measuring the excitations of the resultant BEC. After each iteration the algorithm adjusts its internal model of the system to create an improved control output for the next iteration. Given sufficient control over the decompression, the algorithm converges to a solution that sets the current speed record in relation to the adiabatic timescale, beating out other experimental realizations based on theoretical approaches. This method presents a feasible approach for implementing fast-state preparations or transformations in other quantum systems, without requiring a solution to a theoretical model of the system. Implications for fundamental physics and cooling are discussed.
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25
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Chupeau M, Besga B, Guéry-Odelin D, Trizac E, Petrosyan A, Ciliberto S. Thermal bath engineering for swift equilibration. Phys Rev E 2018; 98:010104. [PMID: 30110875 DOI: 10.1103/physreve.98.010104] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Indexed: 06/08/2023]
Abstract
We provide a theoretical and experimental protocol that dynamically controls the effective temperature of a thermal bath, through a well-designed noise engineering. We use this powerful technique to shortcut the relaxation of an overdamped Brownian particle in a quadratic potential by a joint time engineering of the confinement strength and of the noise. For an optically trapped colloid, we report an equilibrium recovery time reduced by about two orders of magnitude compared to the natural relaxation time. Our scheme paves the way towards reservoir engineering in nanosystems.
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Affiliation(s)
- Marie Chupeau
- LPTMS, CNRS, Université Paris-Sud, Université Paris-Saclay, UMR 8626, 91405 Orsay, France
| | - Benjamin Besga
- CNRS, Laboratoire de Physique de l'École Normale Supérieure, Université de Lyon, UMR 5672, 46 Allée d'Italie, 69364 Lyon, France
| | - David Guéry-Odelin
- Laboratoire de Collisions Agrégats Réactivité, CNRS, UMR 5589, IRSAMC, France
| | - Emmanuel Trizac
- LPTMS, CNRS, Université Paris-Sud, Université Paris-Saclay, UMR 8626, 91405 Orsay, France
| | - Artyom Petrosyan
- CNRS, Laboratoire de Physique de l'École Normale Supérieure, Université de Lyon, UMR 5672, 46 Allée d'Italie, 69364 Lyon, France
| | - Sergio Ciliberto
- CNRS, Laboratoire de Physique de l'École Normale Supérieure, Université de Lyon, UMR 5672, 46 Allée d'Italie, 69364 Lyon, France
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26
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Schäfer VM, Ballance CJ, Thirumalai K, Stephenson LJ, Ballance TG, Steane AM, Lucas DM. Fast quantum logic gates with trapped-ion qubits. Nature 2018; 555:75-78. [DOI: 10.1038/nature25737] [Citation(s) in RCA: 139] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 01/09/2018] [Indexed: 01/14/2023]
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27
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Kaufmann P, Gloger TF, Kaufmann D, Johanning M, Wunderlich C. High-Fidelity Preservation of Quantum Information During Trapped-Ion Transport. PHYSICAL REVIEW LETTERS 2018; 120:010501. [PMID: 29350951 DOI: 10.1103/physrevlett.120.010501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Indexed: 06/07/2023]
Abstract
A promising scheme for building scalable quantum simulators and computers is the synthesis of a scalable system using interconnected subsystems. A prerequisite for this approach is the ability to faithfully transfer quantum information between subsystems. With trapped atomic ions, this can be realized by transporting ions with quantum information encoded into their internal states. Here, we measure with high precision the fidelity of quantum information encoded into hyperfine states of a ^{171}Yb^{+} ion during ion transport in a microstructured Paul trap. Ramsey spectroscopy of the ion's internal state is interleaved with up to 4000 transport operations over a distance of 280 μm each taking 12.8 μs. We obtain a state fidelity of 99.9994( _{-7}^{+6})% per ion transport.
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Affiliation(s)
- Peter Kaufmann
- Department Physik, Naturwissenschaftlich-Technische Fakultät, Universität Siegen, 57068 Siegen, Germany
| | - Timm F Gloger
- Department Physik, Naturwissenschaftlich-Technische Fakultät, Universität Siegen, 57068 Siegen, Germany
| | - Delia Kaufmann
- Department Physik, Naturwissenschaftlich-Technische Fakultät, Universität Siegen, 57068 Siegen, Germany
| | - Michael Johanning
- Department Physik, Naturwissenschaftlich-Technische Fakultät, Universität Siegen, 57068 Siegen, Germany
| | - Christof Wunderlich
- Department Physik, Naturwissenschaftlich-Technische Fakultät, Universität Siegen, 57068 Siegen, Germany
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28
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Poulsen Nautrup H, Friis N, Briegel HJ. Fault-tolerant interface between quantum memories and quantum processors. Nat Commun 2017; 8:1321. [PMID: 29109426 PMCID: PMC5674034 DOI: 10.1038/s41467-017-01418-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 09/14/2017] [Indexed: 11/22/2022] Open
Abstract
Topological error correction codes are promising candidates to protect quantum computations from the deteriorating effects of noise. While some codes provide high noise thresholds suitable for robust quantum memories, others allow straightforward gate implementation needed for data processing. To exploit the particular advantages of different topological codes for fault-tolerant quantum computation, it is necessary to be able to switch between them. Here we propose a practical solution, subsystem lattice surgery, which requires only two-body nearest-neighbor interactions in a fixed layout in addition to the indispensable error correction. This method can be used for the fault-tolerant transfer of quantum information between arbitrary topological subsystem codes in two dimensions and beyond. In particular, it can be employed to create a simple interface, a quantum bus, between noise resilient surface code memories and flexible color code processors. In the quest for fault-tolerant quantum computation, being able to interface different topological codes such as surface and color codes would allow to get the best of each code. Here, the authors show how to interface arbitrary topological quantum error correction codes in two dimensions.
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Affiliation(s)
- Hendrik Poulsen Nautrup
- Institute for Theoretical Physics, University of Innsbruck, Technikerstr. 21a, 6020, Innsbruck, Austria.
| | - Nicolai Friis
- Institute for Theoretical Physics, University of Innsbruck, Technikerstr. 21a, 6020, Innsbruck, Austria.,Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Boltzmanngasse 3, 1090, Vienna, Austria
| | - Hans J Briegel
- Institute for Theoretical Physics, University of Innsbruck, Technikerstr. 21a, 6020, Innsbruck, Austria
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29
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Kaufmann H, Ruster T, Schmiegelow CT, Luda MA, Kaushal V, Schulz J, von Lindenfels D, Schmidt-Kaler F, Poschinger UG. Scalable Creation of Long-Lived Multipartite Entanglement. PHYSICAL REVIEW LETTERS 2017; 119:150503. [PMID: 29077443 DOI: 10.1103/physrevlett.119.150503] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Indexed: 06/07/2023]
Abstract
We demonstrate the deterministic generation of multipartite entanglement based on scalable methods. Four qubits are encoded in ^{40}Ca^{+}, stored in a microstructured segmented Paul trap. These qubits are sequentially entangled by laser-driven pairwise gate operations. Between these, the qubit register is dynamically reconfigured via ion shuttling operations, where ion crystals are separated and merged, and ions are moved in and out of a fixed laser interaction zone. A sequence consisting of three pairwise entangling gates yields a four-ion Greenberger-Horne-Zeilinger state |ψ⟩=(1/sqrt[2])(|0000⟩+|1111⟩), and full quantum state tomography reveals a state fidelity of 94.4(3)%. We analyze the decoherence of this state and employ dynamic decoupling on the spatially distributed constituents to maintain 69(5)% coherence at a storage time of 1.1 sec.
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Affiliation(s)
- H Kaufmann
- Institut für Physik, Universität Mainz, Staudingerweg 7, 55128 Mainz, Germany
| | - T Ruster
- Institut für Physik, Universität Mainz, Staudingerweg 7, 55128 Mainz, Germany
| | - C T Schmiegelow
- Institut für Physik, Universität Mainz, Staudingerweg 7, 55128 Mainz, Germany
| | - M A Luda
- Institut für Physik, Universität Mainz, Staudingerweg 7, 55128 Mainz, Germany
| | - V Kaushal
- Institut für Physik, Universität Mainz, Staudingerweg 7, 55128 Mainz, Germany
| | - J Schulz
- Institut für Physik, Universität Mainz, Staudingerweg 7, 55128 Mainz, Germany
| | - D von Lindenfels
- Institut für Physik, Universität Mainz, Staudingerweg 7, 55128 Mainz, Germany
| | - F Schmidt-Kaler
- Institut für Physik, Universität Mainz, Staudingerweg 7, 55128 Mainz, Germany
| | - U G Poschinger
- Institut für Physik, Universität Mainz, Staudingerweg 7, 55128 Mainz, Germany
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30
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Abstract
We study the shuttling of an atom in a trap with controllable position and frequency. Using invariant-based inverse engineering, protocols in which the trap is simultaneously displaced and expanded are proposed to speed up transport between stationary trap locations as well as launching processes with narrow final-velocity distributions. Depending on the physical constraints imposed, either simultaneous or sequential approaches may be faster. We consider first a perfectly harmonic trap, and then extend the treatment to generic traps. Finally, we apply this general framework to a double-well potential to separate different motional states with different launching velocities.
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31
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Patra A, Jarzynski C. Classical and Quantum Shortcuts to Adiabaticity in a Tilted Piston. J Phys Chem B 2017; 121:3403-3411. [PMID: 27700088 DOI: 10.1021/acs.jpcb.6b08769] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Adiabatic quantum state evolution can be accelerated through a variety of shortcuts to adiabaticity. In one approach, a counterdiabatic quantum Hamiltonian, ĤCD, is constructed to suppress nonadiabatic excitations. In the analogous classical problem, a counterdiabatic classical Hamiltonian, HCD, ensures that the classical action remains constant even under rapid driving. Both the quantum and classical versions of this problem have been solved for the special case of scale-invariant driving, characterized by linear expansions, contractions, or translations of the system. Here we investigate an example of a non-scale-invariant system, a tilted piston. We solve exactly for the classical counterdiabatic Hamiltonian, HCD(q, p, t), which we then quantize to obtain a Hermitian operator, ĤCD(t). Using numerical simulations, we find that ĤCD effectively suppresses nonadiabatic excitations under rapid driving. These results offer a proof of principle, beyond the special case of scale-invariant driving, that quantum shortcuts to adiabaticity can successfully be constructed from their classical counterparts.
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Affiliation(s)
- Ayoti Patra
- Department of Physics, University of Maryland , College Park, Maryland 20742, United States
| | - Christopher Jarzynski
- Department of Physics, University of Maryland , College Park, Maryland 20742, United States.,Department of Chemistry and Biochemistry, University of Maryland , College Park, Maryland 20742, United States.,Institute for Physical Science and Technology, University of Maryland , College Park, Maryland 20742, United States
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32
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Tan TR, Wan Y, Erickson S, Bierhorst P, Kienzler D, Glancy S, Knill E, Leibfried D, Wineland DJ. Chained Bell Inequality Experiment with High-Efficiency Measurements. PHYSICAL REVIEW LETTERS 2017; 118:130403. [PMID: 28409945 DOI: 10.1103/physrevlett.118.130403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Indexed: 06/07/2023]
Abstract
We report correlation measurements on two ^{9}Be^{+} ions that violate a chained Bell inequality obeyed by any local-realistic theory. The correlations can be modeled as derived from a mixture of a local-realistic probabilistic distribution and a distribution that violates the inequality. A statistical framework is formulated to quantify the local-realistic fraction allowable in the observed distribution without the fair-sampling or independent-and-identical-distributions assumptions. We exclude models of our experiment whose local-realistic fraction is above 0.327 at the 95% confidence level. This bound is significantly lower than 0.586, the minimum fraction derived from a perfect Clauser-Horne-Shimony-Holt inequality experiment. Furthermore, our data provide a device-independent certification of the deterministically created Bell states.
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Affiliation(s)
- T R Tan
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Y Wan
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - S Erickson
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - P Bierhorst
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - D Kienzler
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - S Glancy
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - E Knill
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
- Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA
| | - D Leibfried
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - D J Wineland
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
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33
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Lekitsch B, Weidt S, Fowler AG, Mølmer K, Devitt SJ, Wunderlich C, Hensinger WK. Blueprint for a microwave trapped ion quantum computer. SCIENCE ADVANCES 2017; 3:e1601540. [PMID: 28164154 PMCID: PMC5287699 DOI: 10.1126/sciadv.1601540] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 12/15/2016] [Indexed: 06/02/2023]
Abstract
The availability of a universal quantum computer may have a fundamental impact on a vast number of research fields and on society as a whole. An increasingly large scientific and industrial community is working toward the realization of such a device. An arbitrarily large quantum computer may best be constructed using a modular approach. We present a blueprint for a trapped ion-based scalable quantum computer module, making it possible to create a scalable quantum computer architecture based on long-wavelength radiation quantum gates. The modules control all operations as stand-alone units, are constructed using silicon microfabrication techniques, and are within reach of current technology. To perform the required quantum computations, the modules make use of long-wavelength radiation-based quantum gate technology. To scale this microwave quantum computer architecture to a large size, we present a fully scalable design that makes use of ion transport between different modules, thereby allowing arbitrarily many modules to be connected to construct a large-scale device. A high error-threshold surface error correction code can be implemented in the proposed architecture to execute fault-tolerant operations. With appropriate adjustments, the proposed modules are also suitable for alternative trapped ion quantum computer architectures, such as schemes using photonic interconnects.
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Affiliation(s)
- Bjoern Lekitsch
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, U.K
| | - Sebastian Weidt
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, U.K
| | | | - Klaus Mølmer
- Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Simon J. Devitt
- Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama 315-0198, Japan
| | - Christof Wunderlich
- Department Physik, Naturwissenschaftlich-Technische Fakultät, Universität Siegen, 57068 Siegen, Germany
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34
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Shortcuts to adiabaticity by counterdiabatic driving for trapped-ion displacement in phase space. Nat Commun 2016; 7:12999. [PMID: 27669897 PMCID: PMC5052658 DOI: 10.1038/ncomms12999] [Citation(s) in RCA: 133] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 08/19/2016] [Indexed: 11/22/2022] Open
Abstract
The application of adiabatic protocols in quantum technologies is severely limited by environmental sources of noise and decoherence. Shortcuts to adiabaticity by counterdiabatic driving constitute a powerful alternative that speed up time-evolution while mimicking adiabatic dynamics. Here we report the experimental implementation of counterdiabatic driving in a continuous variable system, a shortcut to the adiabatic transport of a trapped ion in phase space. The resulting dynamics is equivalent to a ‘fast-motion video' of the adiabatic trajectory. The robustness of this protocol is shown to surpass that of competing schemes based on classical local controls and Fourier optimization methods. Our results demonstrate that shortcuts to adiabaticity provide a robust speedup of quantum protocols of wide applicability in quantum technologies. The application of adiabatic protocols in quantum technologies is limited due to the detrimental action of decoherence. Here the authors demonstrate a shortcut to adiabaticity via counterdiabatic driving in a trapped ion system.
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Martínez IA, Petrosyan A, Guéry-Odelin D, Trizac E, Ciliberto S. Engineered Swift Equilibration of a Brownian particle. NATURE PHYSICS 2016; 12:843-846. [PMID: 27610190 PMCID: PMC5011424 DOI: 10.1038/nphys3758] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
A fundamental and intrinsic property of any device or natural system is its relaxation time relax, which is the time it takes to return to equilibrium after the sudden change of a control parameter [1]. Reducing τrelax, is frequently necessary, and is often obtained by a complex feedback process. To overcome the limitations of such an approach, alternative methods based on driving have been recently demonstrated [2, 3], for isolated quantum and classical systems [4-9]. Their extension to open systems in contact with a thermostat is a stumbling block for applications. Here, we design a protocol, named Engineered Swift Equilibration (ESE), that shortcuts time-consuming relaxations, and we apply it to a Brownian particle trapped in an optical potential whose properties can be controlled in time. We implement the process experimentally, showing that it allows the system to reach equilibrium times faster than the natural equilibration rate. We also estimate the increase of the dissipated energy needed to get such a time reduction. The method paves the way for applications in micro and nano devices, where the reduction of operation time represents as substantial a challenge as miniaturization [10].
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Affiliation(s)
- Ignacio A Martínez
- Laboratoire de Physique, CNRS UMR5672, Université de Lyon, École Normale Supérieure, 46 Allée d'Italie, 69364 Lyon, France
| | - Artyom Petrosyan
- Laboratoire de Physique, CNRS UMR5672, Université de Lyon, École Normale Supérieure, 46 Allée d'Italie, 69364 Lyon, France
| | - David Guéry-Odelin
- Laboratoire Collisions Agrégats Réactivité, CNRS UMR5589, Université de Toulouse, 31062 Toulouse, France
| | - Emmanuel Trizac
- LPTMS, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay, France
| | - Sergio Ciliberto
- Laboratoire de Physique, CNRS UMR5672, Université de Lyon, École Normale Supérieure, 46 Allée d'Italie, 69364 Lyon, France
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Gaebler JP, Tan TR, Lin Y, Wan Y, Bowler R, Keith AC, Glancy S, Coakley K, Knill E, Leibfried D, Wineland DJ. High-Fidelity Universal Gate Set for ^{9}Be^{+} Ion Qubits. PHYSICAL REVIEW LETTERS 2016; 117:060505. [PMID: 27541451 DOI: 10.1103/physrevlett.117.060505] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Indexed: 06/06/2023]
Abstract
We report high-fidelity laser-beam-induced quantum logic gates on magnetic-field-insensitive qubits comprised of hyperfine states in ^{9}Be^{+} ions with a memory coherence time of more than 1 s. We demonstrate single-qubit gates with an error per gate of 3.8(1)×10^{-5}. By creating a Bell state with a deterministic two-qubit gate, we deduce a gate error of 8(4)×10^{-4}. We characterize the errors in our implementation and discuss methods to further reduce imperfections towards values that are compatible with fault-tolerant processing at realistic overhead.
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Affiliation(s)
- J P Gaebler
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - T R Tan
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - Y Lin
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - Y Wan
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - R Bowler
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - A C Keith
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - S Glancy
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - K Coakley
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - E Knill
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - D Leibfried
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - D J Wineland
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
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37
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Possa GC, Roncaratti LF. Stability Diagrams for Paul Ion Traps Driven by Two-Frequencies. J Phys Chem A 2016; 120:4915-22. [PMID: 26881458 DOI: 10.1021/acs.jpca.5b12543] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this paper, we present and discuss stability diagrams for Paul traps driven by two ac voltages. In contrast to a typical Paul trap, here we suggest a secondary ac voltage whose frequency is twice the frequency of the primary one. The ratio between their amplitudes can be used to expand the region of stability and to access different states of motion of trapped ions. This provides a further mechanism to trap, cool, and manipulate single ions and also to improve the experimental framework where ion clouds and crystals can be prepared and controlled. Such approach opens the possibility of designing more sophisticated trapping architectures, leading to a wide variety of applications on ion trap research and mass analysis techniques.
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Affiliation(s)
- Gabriela C Possa
- Instituto de Física, Universidade de Brasília , 70910 Brasília, Brazil.,Faculdade Gama, Universidade de Brasília , 72444, Gama, Brazil
| | - Luiz F Roncaratti
- Instituto de Física, Universidade de Brasília , 70910 Brasília, Brazil
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Estimation of a general time-dependent Hamiltonian for a single qubit. Nat Commun 2016; 7:11218. [PMID: 27075230 PMCID: PMC4834628 DOI: 10.1038/ncomms11218] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 03/01/2016] [Indexed: 11/15/2022] Open
Abstract
The Hamiltonian of a closed quantum system governs its complete time evolution. While Hamiltonians with time-variation in a single basis can be recovered using a variety of methods, for more general Hamiltonians the presence of non-commuting terms complicates the reconstruction. Here using a single trapped ion, we propose and experimentally demonstrate a method for estimating a time-dependent Hamiltonian of a single qubit. We measure the time evolution of the qubit in a fixed basis as a function of a time-independent offset term added to the Hamiltonian. The initially unknown Hamiltonian arises from transporting an ion through a static laser beam. Hamiltonian estimation allows us to estimate the spatial beam intensity profile and the ion velocity as a function of time. The estimation technique is general enough that it can be applied to other quantum systems, aiding the pursuit of high-operational fidelities in quantum control. Time-varying Hamiltonians can be reconstructed experimentally if the variation takes place in a single basis, but more general cases are complicated. Here, the authors present an approach to estimate the general time-dependent Hamiltonian of a single spin-qubit and apply it to a trapped-ion transported through a static laser beam.
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Generation of large coherent states by bang-bang control of a trapped-ion oscillator. Nat Commun 2016; 7:11243. [PMID: 27046513 PMCID: PMC4822070 DOI: 10.1038/ncomms11243] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 03/03/2016] [Indexed: 11/20/2022] Open
Abstract
Fast control of quantum systems is essential to make use of quantum properties before they degrade by decoherence. This is important for quantum-enhanced information processing, as well as for pushing quantum systems towards the boundary between quantum and classical physics. ‘Bang–bang' control attains the ultimate speed limit by making large changes to control fields much faster than the system can respond, but is often challenging to implement experimentally. Here we demonstrate bang–bang control of a trapped-ion oscillator using nanosecond switching of the trapping potentials. We perform controlled displacements with which we realize coherent states with up to 10,000 quanta of energy. We use these displaced states to verify the form of the ion-light interaction at high excitations far outside the usual regime of operation. These methods provide new possibilities for quantum-state manipulation and generation, alongside the potential for a significant increase in operational clock speed for trapped-ion quantum information processing. Fast control of quantum systems is essential to exploit their properties for information processing before they are lost to decoherence. Here the authors demonstrate the use of quasi instantaneous changes to the trapping potential of a trapped-ion to create highly-excited quantum coherent states.
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de Clercq LE, Lo HY, Marinelli M, Nadlinger D, Oswald R, Negnevitsky V, Kienzler D, Keitch B, Home JP. Parallel Transport Quantum Logic Gates with Trapped Ions. PHYSICAL REVIEW LETTERS 2016; 116:080502. [PMID: 26967401 DOI: 10.1103/physrevlett.116.080502] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Indexed: 06/05/2023]
Abstract
We demonstrate single-qubit operations by transporting a beryllium ion with a controlled velocity through a stationary laser beam. We use these to perform coherent sequences of quantum operations, and to perform parallel quantum logic gates on two ions in different processing zones of a multiplexed ion trap chip using a single recycled laser beam. For the latter, we demonstrate individually addressed single-qubit gates by local control of the speed of each ion. The fidelities we observe are consistent with operations performed using standard methods involving static ions and pulsed laser fields. This work therefore provides a path to scalable ion trap quantum computing with reduced requirements on the optical control complexity.
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Affiliation(s)
- Ludwig E de Clercq
- Institute for Quantum Electronics, ETH Zürich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland
| | - Hsiang-Yu Lo
- Institute for Quantum Electronics, ETH Zürich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland
| | - Matteo Marinelli
- Institute for Quantum Electronics, ETH Zürich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland
| | - David Nadlinger
- Institute for Quantum Electronics, ETH Zürich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland
| | - Robin Oswald
- Institute for Quantum Electronics, ETH Zürich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland
| | - Vlad Negnevitsky
- Institute for Quantum Electronics, ETH Zürich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland
| | - Daniel Kienzler
- Institute for Quantum Electronics, ETH Zürich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland
| | - Ben Keitch
- Institute for Quantum Electronics, ETH Zürich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland
| | - Jonathan P Home
- Institute for Quantum Electronics, ETH Zürich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland
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Affiliation(s)
- Dalton T. Snyder
- Department of Chemistry and Center for Analytical Instrumentation
Development, Purdue University, W. Lafayette, IN 47907
| | - Christopher J. Pulliam
- Department of Chemistry and Center for Analytical Instrumentation
Development, Purdue University, W. Lafayette, IN 47907
| | - Zheng Ouyang
- Weldon School of Biomedical Engineering, Purdue University, W.
Lafayette, IN 47907
| | - R. Graham Cooks
- Department of Chemistry and Center for Analytical Instrumentation
Development, Purdue University, W. Lafayette, IN 47907
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Masuda S, Rice SA. Rotation of the Orientation of the Wave Function Distribution of a Charged Particle and its Utilization. J Phys Chem B 2015; 119:11079-88. [PMID: 26047209 DOI: 10.1021/acs.jpcb.5b02681] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Shumpei Masuda
- QCD
Laboratories, Department of Applied Physics, Aalto University, Aalto 00076, Finland
| | - Stuart A. Rice
- James
Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States
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43
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Masuda S, Nakamura K, del Campo A. High-fidelity rapid ground-state loading of an ultracold gas into an optical lattice. PHYSICAL REVIEW LETTERS 2014; 113:063003. [PMID: 25148323 DOI: 10.1103/physrevlett.113.063003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2014] [Indexed: 06/03/2023]
Abstract
A protocol is proposed for the rapid coherent loading of a Bose-Einstein condensate into the ground state of an optical lattice, without residual excitation associated with the breakdown of adiabaticity. The driving potential required to assist the rapid loading is derived using the fast-forward technique, and generates the ground state in any desired short time. We propose an experimentally feasible loading scheme using a bichromatic lattice potential, which approximates the fast-forward driving potential with high fidelity.
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Affiliation(s)
- Shumpei Masuda
- The James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA and Department of Physics, Tohoku University, Sendai 980, Japan
| | - Katsuhiro Nakamura
- Turin Polytechnic University in Tashkent, 17 Niyazov Street, Tashkent 100095, Uzbekistan and Department of Applied Physics, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan
| | - Adolfo del Campo
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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Zheng Y, Poletti D. Work and efficiency of quantum Otto cycles in power-law trapping potentials. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:012145. [PMID: 25122289 DOI: 10.1103/physreve.90.012145] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Indexed: 06/03/2023]
Abstract
We study the performance of a quantum Otto cycle operating in trapping potentials of different shapes. We show that, while both the mean work output and the efficiency of two Otto cycles in different trapping potentials can be made equal, the work probability distribution will still be strongly affected by the difference in structure of the energy levels. To exemplify our results, we study the family of potentials of the form V(t)(x) ∼ x(2q). This family of potentials possesses a simple scaling property that allows for analytical insights into the efficiency and work output of the cycle. We perform a comparison of quantum Otto cycles in various physically relevant scenarios and find that in certain instances, the efficiency of the cycle is greater when using potentials with larger values of q, while in other cases, the efficiency is greater with harmonic traps.
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Affiliation(s)
- Yuanjian Zheng
- Singapore University of Technology and Design, 20 Dover Drive, 138682 Singapore
| | - Dario Poletti
- Singapore University of Technology and Design, 20 Dover Drive, 138682 Singapore
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45
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Baig MT, Johanning M, Wiese A, Heidbrink S, Ziolkowski M, Wunderlich C. A scalable, fast, and multichannel arbitrary waveform generator. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2013; 84:124701. [PMID: 24387448 DOI: 10.1063/1.4832042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This article reports on the development of a multichannel arbitrary waveform generator that simultaneously generates arbitrary voltage waveforms on 24 independent channels with a dynamic update rate of up to 25 Msps. A real-time execution of a single waveform and/or sequence of multiple waveforms in succession, with a user programmable arbitrary sequence order is provided under the control of a stand-alone sequencer circuit implemented using a field programmable gate array. The device is operated using an internal clock and can be synced to other devices by means of transistor-transistor logic (TTL) pulses. The device can provide up to 24 independent voltages in the range of up to ± 9 V with a dynamic update-rate of up to 25 Msps and a power consumption of less than 35 W. Every channel can be programmed for 16 independent arbitrary waveforms that can be accessed during run time with a minimum switching delay of 160 ns. The device has a low-noise of 250 μV(rms) and provides a stable long-term operation with a drift rate below 10 μV/min and a maximum deviation less than ± 300 μV(pp) over a period of 2 h.
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Affiliation(s)
- M T Baig
- Department of Physics, University of Siegen, Walter-Flex-Strasse 3, Siegen NRW 57072, Germany
| | - M Johanning
- Department of Physics, University of Siegen, Walter-Flex-Strasse 3, Siegen NRW 57072, Germany
| | - A Wiese
- Department of Physics, University of Siegen, Walter-Flex-Strasse 3, Siegen NRW 57072, Germany
| | - S Heidbrink
- Department of Physics, University of Siegen, Walter-Flex-Strasse 3, Siegen NRW 57072, Germany
| | - M Ziolkowski
- Department of Physics, University of Siegen, Walter-Flex-Strasse 3, Siegen NRW 57072, Germany
| | - C Wunderlich
- Department of Physics, University of Siegen, Walter-Flex-Strasse 3, Siegen NRW 57072, Germany
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46
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Martínez-Garaot S, Torrontegui E, Chen X, Modugno M, Guéry-Odelin D, Tseng SY, Muga JG. Vibrational mode multiplexing of ultracold atoms. PHYSICAL REVIEW LETTERS 2013; 111:213001. [PMID: 24313484 DOI: 10.1103/physrevlett.111.213001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 10/11/2013] [Indexed: 06/02/2023]
Abstract
Sending multiple messages on qubits encoded in different vibrational modes of cold atoms or ions along a transmission waveguide requires us to merge first and then separate the modes at input and output ends. Similarly, different qubits can be stored in the modes of a trap and be separated later. We design the fast splitting of a harmonic trap into an asymmetric double well so that the initial ground vibrational state becomes the ground state of one of two final wells, and the initial first excited state becomes the ground state of the other well. This might be done adiabatically by slowly deforming the trap. We speed up the process by inverse engineering a double-function trap using dynamical invariants. The separation (demultiplexing) followed by an inversion of the asymmetric bias and then by the reverse process (multiplexing) provides a population inversion protocol based solely on trap reshaping.
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Affiliation(s)
- S Martínez-Garaot
- Departamento de Química Física, UPV/EHU, Apdo. 644, 48080 Bilbao, Spain
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del Campo A. Shortcuts to adiabaticity by counterdiabatic driving. PHYSICAL REVIEW LETTERS 2013; 111:100502. [PMID: 25166641 DOI: 10.1103/physrevlett.111.100502] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Indexed: 05/26/2023]
Abstract
The evolution of a system induced by counterdiabatic driving mimics the adiabatic dynamics without the requirement of slow driving. Engineering it involves diagonalizing the instantaneous Hamiltonian of the system and results in the need of auxiliary nonlocal interactions for matter waves. Here, experimentally realizable driving protocols are found for a large class of single-particle, many-body, and nonlinear systems without demanding the spectral properties as an input. The method is applied to the fast decompression of Bose-Einstein condensates in different trapping potentials.
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Affiliation(s)
- Adolfo del Campo
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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48
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Warring U, Ospelkaus C, Colombe Y, Jördens R, Leibfried D, Wineland DJ. Individual-ion addressing with microwave field gradients. PHYSICAL REVIEW LETTERS 2013; 110:173002. [PMID: 23679718 DOI: 10.1103/physrevlett.110.173002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Indexed: 06/02/2023]
Abstract
Individual-qubit addressing is a prerequisite for many instances of quantum information processing. We demonstrate this capability on trapped-ion qubits with microwave near fields delivered by electrode structures integrated into a microfabricated surface-electrode trap. We describe four approaches that may be used in quantum information experiments with hyperfine levels as qubits. We implement individual control on two 25Mg+ ions separated by 4.3 μm and find spin-flip crosstalk errors on the order of 10(-3).
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Affiliation(s)
- U Warring
- Time and Frequency Division, National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA.
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Bowler R, Warring U, Britton JW, Sawyer BC, Amini J. Arbitrary waveform generator for quantum information processing with trapped ions. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2013; 84:033108. [PMID: 23556808 DOI: 10.1063/1.4795552] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Atomic ions confined in multi-electrode traps have been proposed as a basis for scalable quantum information processing. This scheme involves transporting ions between spatially distinct locations by use of time-varying electric potentials combined with laser or microwave pulses for quantum logic in specific locations. We report the development of a fast multi-channel arbitrary waveform generator for applying the time-varying electric potentials used for transport and for shaping quantum logic pulses. The generator is based on a field-programmable gate array controlled ensemble of 16-bit digital-to-analog converters with an update frequency of 50 MHz and an output range of ±10 V. The update rate of the waveform generator is much faster than relevant motional frequencies of the confined ions in our experiments, allowing diabatic control of the ion motion. Numerous pre-loaded sets of time-varying voltages can be selected with 40 ns latency conditioned on real-time signals. Here we describe the device and demonstrate some of its uses in ion-based quantum information experiments, including speed-up of ion transport and the shaping of laser and microwave pulses.
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Affiliation(s)
- R Bowler
- National Institute of Standards and Technology, Boulder, Colorado 80305, USA.
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