1
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Malinowski M, Zhang C, Negnevitsky V, Rojkov I, Reiter F, Nguyen TL, Stadler M, Kienzler D, Mehta KK, Home JP. Generation of a Maximally Entangled State Using Collective Optical Pumping. PHYSICAL REVIEW LETTERS 2022; 128:080503. [PMID: 35275689 DOI: 10.1103/physrevlett.128.080503] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 12/10/2021] [Accepted: 01/11/2022] [Indexed: 06/14/2023]
Abstract
We propose and implement a novel scheme for dissipatively pumping two qubits into a singlet Bell state. The method relies on a process of collective optical pumping to an excited level, to which all states apart from the singlet are coupled. We apply the method to deterministically entangle two trapped ^{40}Ca^{+} ions. Within 16 pumping cycles, an initially separable state is transformed into one with 83(1)% singlet fidelity, and states with initial fidelity of ⪆70% converge onto a fidelity of 93(1)%. We theoretically analyze the performance and error susceptibility of the scheme and find it to be insensitive to a large class of experimentally relevant noise sources.
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Affiliation(s)
- M Malinowski
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
| | - C Zhang
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
| | - V Negnevitsky
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
| | - I Rojkov
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
| | - F Reiter
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
| | - T-L Nguyen
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
| | - M Stadler
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
| | - D Kienzler
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
| | - K K Mehta
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
| | - J P Home
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
- Quantum center, ETH Zürich, 8093 Zürich, Switzerland
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2
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Clark CR, Tinkey HN, Sawyer BC, Meier AM, Burkhardt KA, Seck CM, Shappert CM, Guise ND, Volin CE, Fallek SD, Hayden HT, Rellergert WG, Brown KR. High-Fidelity Bell-State Preparation with ^{40}Ca^{+} Optical Qubits. PHYSICAL REVIEW LETTERS 2021; 127:130505. [PMID: 34623832 DOI: 10.1103/physrevlett.127.130505] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 08/19/2021] [Indexed: 05/02/2023]
Abstract
Entanglement generation in trapped-ion systems has relied thus far on two distinct but related geometric phase gate techniques: Mølmer-Sørensen and light-shift gates. We recently proposed a variant of the light-shift scheme where the qubit levels are separated by an optical frequency [B. C. Sawyer and K. R. Brown, Phys. Rev. A 103, 022427 (2021)PLRAAN2469-992610.1103/PhysRevA.103.022427]. Here we report an experimental demonstration of this entangling gate using a pair of ^{40}Ca^{+} ions in a cryogenic surface-electrode ion trap and a commercial, high-power, 532 nm Nd:YAG laser. Generating a Bell state in 35 μs, we directly measure an infidelity of 6(3)×10^{-4} without subtraction of experimental errors. The 532 nm gate laser wavelength suppresses intrinsic photon scattering error to ∼1×10^{-5}.
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Affiliation(s)
- Craig R Clark
- Georgia Tech Research Institute, Atlanta, Georgia 30332, USA
| | - Holly N Tinkey
- Georgia Tech Research Institute, Atlanta, Georgia 30332, USA
| | - Brian C Sawyer
- Georgia Tech Research Institute, Atlanta, Georgia 30332, USA
| | - Adam M Meier
- Georgia Tech Research Institute, Atlanta, Georgia 30332, USA
| | | | | | | | | | - Curtis E Volin
- Georgia Tech Research Institute, Atlanta, Georgia 30332, USA
| | | | - Harley T Hayden
- Georgia Tech Research Institute, Atlanta, Georgia 30332, USA
| | | | - Kenton R Brown
- Georgia Tech Research Institute, Atlanta, Georgia 30332, USA
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3
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Srinivas R, Burd SC, Knaack HM, Sutherland RT, Kwiatkowski A, Glancy S, Knill E, Wineland DJ, Leibfried D, Wilson AC, Allcock DTC, Slichter DH. High-fidelity laser-free universal control of trapped ion qubits. Nature 2021; 597:209-213. [PMID: 34497396 PMCID: PMC11165722 DOI: 10.1038/s41586-021-03809-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 07/07/2021] [Indexed: 11/09/2022]
Abstract
Universal control of multiple qubits-the ability to entangle qubits and to perform arbitrary individual qubit operations1-is a fundamental resource for quantum computing2, simulation3 and networking4. Qubits realized in trapped atomic ions have shown the highest-fidelity two-qubit entangling operations5-7 and single-qubit rotations8 so far. Universal control of trapped ion qubits has been separately demonstrated using tightly focused laser beams9-12 or by moving ions with respect to laser beams13-15, but at lower fidelities. Laser-free entangling methods16-20 may offer improved scalability by harnessing microwave technology developed for wireless communications, but so far their performance has lagged the best reported laser-based approaches. Here we demonstrate high-fidelity laser-free universal control of two trapped-ion qubits by creating both symmetric and antisymmetric maximally entangled states with fidelities of [Formula: see text] and [Formula: see text], respectively (68 per cent confidence level), corrected for initialization error. We use a scheme based on radiofrequency magnetic field gradients combined with microwave magnetic fields that is robust against multiple sources of decoherence and usable with essentially any trapped ion species. The scheme has the potential to perform simultaneous entangling operations on multiple pairs of ions in a large-scale trapped-ion quantum processor without increasing control signal power or complexity. Combining this technology with low-power laser light delivered via trap-integrated photonics21,22 and trap-integrated photon detectors for qubit readout23,24 provides an opportunity for scalable, high-fidelity, fully chip-integrated trapped-ion quantum computing.
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Affiliation(s)
- R Srinivas
- National Institute of Standards and Technology, Boulder, CO, USA.
- Department of Physics, University of Colorado, Boulder, CO, USA.
- Department of Physics, Clarendon Laboratory, University of Oxford, Oxford, UK.
| | - S C Burd
- National Institute of Standards and Technology, Boulder, CO, USA
- Department of Physics, University of Colorado, Boulder, CO, USA
- Department of Physics, Stanford University, Stanford, CA, USA
| | - H M Knaack
- National Institute of Standards and Technology, Boulder, CO, USA
- Department of Physics, University of Colorado, Boulder, CO, USA
| | - R T Sutherland
- Physics Division, Physical and Life Sciences, Lawrence Livermore National Laboratory, Livermore, CA, USA
- Department of Electrical and Computer Engineering, University of Texas at San Antonio, San Antonio, TX, USA
- Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX, USA
| | - A Kwiatkowski
- National Institute of Standards and Technology, Boulder, CO, USA
- Department of Physics, University of Colorado, Boulder, CO, USA
| | - S Glancy
- National Institute of Standards and Technology, Boulder, CO, USA
| | - E Knill
- National Institute of Standards and Technology, Boulder, CO, USA
- Center for Theory of Quantum Matter, University of Colorado, Boulder, CO, USA
| | - D J Wineland
- National Institute of Standards and Technology, Boulder, CO, USA
- Department of Physics, University of Colorado, Boulder, CO, USA
- Department of Physics, University of Oregon, Eugene, OR, USA
| | - D Leibfried
- National Institute of Standards and Technology, Boulder, CO, USA
| | - A C Wilson
- National Institute of Standards and Technology, Boulder, CO, USA
| | - D T C Allcock
- National Institute of Standards and Technology, Boulder, CO, USA
- Department of Physics, University of Colorado, Boulder, CO, USA
- Department of Physics, University of Oregon, Eugene, OR, USA
| | - D H Slichter
- National Institute of Standards and Technology, Boulder, CO, USA.
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4
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Milne AR, Hempel C, Li L, Edmunds CL, Slatyer HJ, Ball H, Hush MR, Biercuk MJ. Quantum Oscillator Noise Spectroscopy via Displaced Cat States. PHYSICAL REVIEW LETTERS 2021; 126:250506. [PMID: 34241523 DOI: 10.1103/physrevlett.126.250506] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 04/21/2021] [Indexed: 06/13/2023]
Abstract
Quantum harmonic oscillators are central to many modern quantum technologies. We introduce a method to determine the frequency noise spectrum of oscillator modes through coupling them to a qubit with continuously driven qubit-state-dependent displacements. We reconstruct the noise spectrum using a series of different drive phase and amplitude modulation patterns in conjunction with a data-fusion routine based on convex optimization. We apply the technique to the identification of intrinsic noise in the motional frequency of a single trapped ion with sensitivity to fluctuations at the sub-Hz level in a spectral range from quasi-dc up to 50 kHz.
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Affiliation(s)
- Alistair R Milne
- ARC Centre of Excellence for Engineered Quantum Systems, The University of Sydney, School of Physics, New South Wales 2006, Australia
| | - Cornelius Hempel
- ARC Centre of Excellence for Engineered Quantum Systems, The University of Sydney, School of Physics, New South Wales 2006, Australia
| | - Li Li
- Q-CTRL Pty Ltd, Sydney, New South Wales 2006, Australia
| | - Claire L Edmunds
- ARC Centre of Excellence for Engineered Quantum Systems, The University of Sydney, School of Physics, New South Wales 2006, Australia
| | | | - Harrison Ball
- Q-CTRL Pty Ltd, Sydney, New South Wales 2006, Australia
| | | | - Michael J Biercuk
- ARC Centre of Excellence for Engineered Quantum Systems, The University of Sydney, School of Physics, New South Wales 2006, Australia
- Q-CTRL Pty Ltd, Sydney, New South Wales 2006, Australia
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5
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Blümel R, Grzesiak N, Nguyen NH, Green AM, Li M, Maksymov A, Linke NM, Nam Y. Efficient Stabilized Two-Qubit Gates on a Trapped-Ion Quantum Computer. PHYSICAL REVIEW LETTERS 2021; 126:220503. [PMID: 34152167 DOI: 10.1103/physrevlett.126.220503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 05/04/2021] [Indexed: 06/13/2023]
Abstract
In order to scale up quantum processors and achieve a quantum advantage, it is crucial to economize on the power requirement of two-qubit gates, make them robust to drift in experimental parameters, and shorten the gate times. Applicable to all quantum computer architectures whose two-qubit gates rely on phase-space closure, we present here a new gate-optimizing principle according to which negligible amounts of gate fidelity are traded for substantial savings in power, which, in turn, can be traded for substantial increases in gate speed and/or qubit connectivity. As a concrete example, we illustrate the method by constructing optimal pulses for entangling gates on a pair of ions within a trapped-ion chain, one of the leading quantum computing architectures. Our method is direct, noniterative, and linear, and, in some parameter regimes, constructs gate-steering pulses requiring up to an order of magnitude less power than the standard method. Additionally, our method provides increased robustness to mode drift. We verify the new trade-off principle experimentally on our trapped-ion quantum computer.
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Affiliation(s)
- Reinhold Blümel
- Wesleyan University, Middletown, Connecticut 06459, USA
- IonQ, College Park, Maryland 20740, USA
| | | | - Nhung H Nguyen
- Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA
| | - Alaina M Green
- Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA
| | - Ming Li
- IonQ, College Park, Maryland 20740, USA
| | | | - Norbert M Linke
- Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA
| | - Yunseong Nam
- IonQ, College Park, Maryland 20740, USA
- Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA
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6
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Hughes AC, Schäfer VM, Thirumalai K, Nadlinger DP, Woodrow SR, Lucas DM, Ballance CJ. Benchmarking a High-Fidelity Mixed-Species Entangling Gate. PHYSICAL REVIEW LETTERS 2020; 125:080504. [PMID: 32909787 DOI: 10.1103/physrevlett.125.080504] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 07/08/2020] [Indexed: 06/11/2023]
Abstract
We implement a two-qubit logic gate between a ^{43}Ca^{+} hyperfine qubit and a ^{88}Sr^{+} Zeeman qubit. For this pair of ion species, the S-P optical transitions are close enough that a single laser of wavelength 402 nm can be used to drive the gate but sufficiently well separated to give good spectral isolation and low photon scattering errors. We characterize the gate by full randomized benchmarking, gate set tomography, and Bell state analysis. The latter method gives a fidelity of 99.8(1)%, comparable to that of the best same-species gates and consistent with known sources of error.
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Affiliation(s)
- A C Hughes
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - V M Schäfer
- 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
| | - D P Nadlinger
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - S R Woodrow
- 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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7
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Zarantonello G, Hahn H, Morgner J, Schulte M, Bautista-Salvador A, Werner RF, Hammerer K, Ospelkaus C. Robust and Resource-Efficient Microwave Near-Field Entangling ^{9}Be^{+} Gate. PHYSICAL REVIEW LETTERS 2019; 123:260503. [PMID: 31951443 DOI: 10.1103/physrevlett.123.260503] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Indexed: 06/10/2023]
Abstract
Microwave trapped-ion quantum logic gates avoid spontaneous emission as a fundamental source of decoherence. However, microwave two-qubit gates are still slower than laser-induced gates and hence more sensitive to fluctuations and noise of the motional mode frequency. We propose and implement amplitude-shaped gate drives to obtain resilience to such frequency changes without increasing the pulse energy per gate operation. We demonstrate the resilience by noise injection during a two-qubit entangling gate with ^{9}Be^{+} ion qubits. In the absence of injected noise, amplitude modulation gives an operation infidelity in the 10^{-3} range.
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Affiliation(s)
- G Zarantonello
- Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover, Germany
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
| | - H Hahn
- Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover, Germany
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
| | - J Morgner
- Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover, Germany
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
| | - M Schulte
- Institut für Theoretische Physik und Institut für Gravitationsphysik (Albert-Einstein-Institut), Leibniz Universität Hannover, Appelstrasse 2, 30167 Hannover, Germany
| | - A Bautista-Salvador
- Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover, Germany
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
- Laboratorium für Nano- und Quantenengineering, Leibniz Universität Hannover, Schneiderberg 39, 30167 Hannover, Germany
| | - R F Werner
- Institut für Theoretische Physik, Leibniz Universität Hannover, Appelstrasse 2, 30167 Hannover, Germany
| | - K Hammerer
- Institut für Theoretische Physik und Institut für Gravitationsphysik (Albert-Einstein-Institut), Leibniz Universität Hannover, Appelstrasse 2, 30167 Hannover, Germany
| | - C Ospelkaus
- Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover, Germany
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
- Laboratorium für Nano- und Quantenengineering, Leibniz Universität Hannover, Schneiderberg 39, 30167 Hannover, Germany
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8
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Webb AE, Webster SC, Collingbourne S, Bretaud D, Lawrence AM, Weidt S, Mintert F, Hensinger WK. Resilient Entangling Gates for Trapped Ions. PHYSICAL REVIEW LETTERS 2018; 121:180501. [PMID: 30444422 DOI: 10.1103/physrevlett.121.180501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Indexed: 06/09/2023]
Abstract
Constructing a large-scale ion trap quantum processor will require entangling gate operations that are robust in the presence of noise and experimental imperfection. We experimentally demonstrate how a new type of Mølmer-Sørensen gate protects against infidelity caused by heating of the motional mode used during the gate. Furthermore, we show how the same technique simultaneously provides significant protection against slow fluctuations and mis-sets in the secular frequency. Since this parameter sensitivity is worsened in cases where the ions are not ground-state cooled, our method provides a path towards relaxing ion cooling requirements in practical realizations of quantum computing and simulation.
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Affiliation(s)
- A E Webb
- Department of Physics and Astronomy, University of Sussex, Brighton, BN1 9QH, United Kingdom
| | - S C Webster
- Department of Physics and Astronomy, University of Sussex, Brighton, BN1 9QH, United Kingdom
| | - S Collingbourne
- QOLS, Blackett Laboratory, Imperial College London, London, SW7 2BW, United Kingdom
| | - D Bretaud
- Department of Physics and Astronomy, University of Sussex, Brighton, BN1 9QH, United Kingdom
- QOLS, Blackett Laboratory, Imperial College London, London, SW7 2BW, United Kingdom
| | - A M Lawrence
- Department of Physics and Astronomy, University of Sussex, Brighton, BN1 9QH, United Kingdom
- QOLS, Blackett Laboratory, Imperial College London, London, SW7 2BW, United Kingdom
| | - S Weidt
- Department of Physics and Astronomy, University of Sussex, Brighton, BN1 9QH, United Kingdom
| | - F Mintert
- QOLS, Blackett Laboratory, Imperial College London, London, SW7 2BW, United Kingdom
| | - W K Hensinger
- Department of Physics and Astronomy, University of Sussex, Brighton, BN1 9QH, United Kingdom
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9
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Manovitz T, Rotem A, Shaniv R, Cohen I, Shapira Y, Akerman N, Retzker A, Ozeri R. Fast Dynamical Decoupling of the Mølmer-Sørensen Entangling Gate. PHYSICAL REVIEW LETTERS 2017; 119:220505. [PMID: 29286763 DOI: 10.1103/physrevlett.119.220505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Indexed: 06/07/2023]
Abstract
Engineering entanglement between quantum systems often involves coupling through a bosonic mediator, which should be disentangled from the systems at the operation's end. The quality of such an operation is generally limited by environmental and control noise. One of the prime techniques for suppressing noise is by dynamical decoupling, where one actively applies pulses at a rate that is faster than the typical time scale of the noise. However, for boson-mediated gates, current dynamical decoupling schemes require executing the pulses only when the boson and the quantum systems are disentangled. This restriction implies an increase of the gate time by a factor of sqrt[N], with N being the number of pulses applied. Here we propose and realize a method that enables dynamical decoupling in a boson-mediated system where the pulses can be applied while spin-boson entanglement persists, resulting in an increase in time that is at most a factor of π/2, independently of the number of pulses applied. We experimentally demonstrate the robustness of our entangling gate with fast dynamical decoupling to σ_{z} noise using ions in a Paul trap.
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Affiliation(s)
- Tom Manovitz
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Amit Rotem
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Givat Ram, Israel
| | - Ravid Shaniv
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Itsik Cohen
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Givat Ram, Israel
| | - Yotam Shapira
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Nitzan Akerman
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Alex Retzker
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Givat Ram, Israel
| | - Roee Ozeri
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
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10
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Inlek IV, Crocker C, Lichtman M, Sosnova K, Monroe C. Multispecies Trapped-Ion Node for Quantum Networking. PHYSICAL REVIEW LETTERS 2017; 118:250502. [PMID: 28696766 DOI: 10.1103/physrevlett.118.250502] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Indexed: 06/07/2023]
Abstract
Trapped atomic ions are a leading platform for quantum information networks, with long-lived identical qubit memories that can be locally entangled through their Coulomb interaction and remotely entangled through photonic channels. However, performing both local and remote operations in a single node of a quantum network requires extreme isolation between spectator qubit memories and qubits associated with the photonic interface. We achieve this isolation by cotrapping ^{171}Yb^{+} and ^{138}Ba^{+} qubits. We further demonstrate the ingredients of a scalable ion trap network node with two distinct experiments that consist of entangling the mixed species qubit pair through their collective motion and entangling a ^{138}Ba^{+} qubit with an emitted visible photon.
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Affiliation(s)
- I V Inlek
- Joint Quantum Institute and Department of Physics, University of Maryland, College Park, Maryland 20742, USA
| | - C Crocker
- Joint Quantum Institute and Department of Physics, University of Maryland, College Park, Maryland 20742, USA
| | - M Lichtman
- Joint Quantum Institute and Department of Physics, University of Maryland, College Park, Maryland 20742, USA
| | - K Sosnova
- Joint Quantum Institute and Department of Physics, University of Maryland, College Park, Maryland 20742, USA
| | - C Monroe
- Joint Quantum Institute and Department of Physics, University of Maryland, College Park, Maryland 20742, USA
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11
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Harty TP, Sepiol MA, Allcock DTC, Ballance CJ, Tarlton JE, Lucas DM. High-Fidelity Trapped-Ion Quantum Logic Using Near-Field Microwaves. PHYSICAL REVIEW LETTERS 2016; 117:140501. [PMID: 27740823 DOI: 10.1103/physrevlett.117.140501] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Indexed: 06/06/2023]
Abstract
We demonstrate a two-qubit logic gate driven by near-field microwaves in a room-temperature microfabricated surface ion trap. We introduce a dynamically decoupled gate method, which stabilizes the qubits against fluctuating energy shifts and avoids the need to null the microwave field. We use the gate to produce a Bell state with fidelity 99.7(1)%, after accounting for state preparation and measurement errors. The gate is applied directly to ^{43}Ca^{+} hyperfine "atomic clock" qubits (coherence time T_{2}^{*}≈50 s) using the oscillating magnetic field gradient produced by an integrated microwave electrode.
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Affiliation(s)
- T P Harty
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - M A Sepiol
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - D T C Allcock
- 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
| | - J E Tarlton
- 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
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12
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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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13
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Bohnet JG, Sawyer BC, Britton JW, Wall ML, Rey AM, Foss-Feig M, Bollinger JJ. Quantum spin dynamics and entanglement generation with hundreds of trapped ions. Science 2016; 352:1297-301. [PMID: 27284189 DOI: 10.1126/science.aad9958] [Citation(s) in RCA: 103] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 05/04/2016] [Indexed: 11/03/2022]
Abstract
Quantum simulation of spin models can provide insight into problems that are difficult or impossible to study with classical computers. Trapped ions are an established platform for quantum simulation, but only systems with fewer than 20 ions have demonstrated quantum correlations. We studied quantum spin dynamics arising from an engineered, homogeneous Ising interaction in a two-dimensional array of (9)Be(+) ions in a Penning trap. We verified entanglement in spin-squeezed states of up to 219 ions, directly observing 4.0 ± 0.9 decibels of spectroscopic enhancement, and observed states with non-Gaussian statistics consistent with oversqueezed states. The good agreement with ab initio theory that includes interactions and decoherence lays the groundwork for simulations of the transverse-field Ising model with variable-range interactions, which are generally intractable with classical methods.
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Affiliation(s)
- Justin G Bohnet
- National Institute of Standards and Technology (NIST), Boulder, CO 80305, USA.
| | - Brian C Sawyer
- National Institute of Standards and Technology (NIST), Boulder, CO 80305, USA. Georgia Tech Research Institute, Atlanta, GA 30332, USA
| | - Joseph W Britton
- National Institute of Standards and Technology (NIST), Boulder, CO 80305, USA. Army Research Lab, Adelphi, MD 20783, USA
| | - Michael L Wall
- JILA, NIST, and University of Colorado, Boulder, CO 80309, USA
| | - Ana Maria Rey
- JILA, NIST, and Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - Michael Foss-Feig
- Army Research Lab, Adelphi, MD 20783, USA. Joint Quantum Institute and NIST, Gaithersburg, MD 20899, USA
| | - John J Bollinger
- National Institute of Standards and Technology (NIST), Boulder, CO 80305, USA.
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14
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Weidt S, Randall J, Webster SC, Standing ED, Rodriguez A, Webb AE, Lekitsch B, Hensinger WK. Ground-State Cooling of a Trapped Ion Using Long-Wavelength Radiation. PHYSICAL REVIEW LETTERS 2015; 115:013002. [PMID: 26182094 DOI: 10.1103/physrevlett.115.013002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Indexed: 06/04/2023]
Abstract
We demonstrate ground-state cooling of a trapped ion using radio-frequency (rf) radiation. This is a powerful tool for the implementation of quantum operations, where rf or microwave radiation instead of lasers is used for motional quantum state engineering. We measure a mean phonon number of n[over ¯]=0.13(4) after sideband cooling, corresponding to a ground-state occupation probability of 88(7)%. After preparing in the vibrational ground state, we demonstrate motional state engineering by driving Rabi oscillations between the |n=0⟩ and |n=1⟩ Fock states. We also use the ability to ground-state cool to accurately measure the motional heating rate and report a reduction by almost 2 orders of magnitude compared with our previously measured result, which we attribute to carefully eliminating sources of electrical noise in the system.
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Affiliation(s)
- S Weidt
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom
| | - J Randall
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom
- QOLS, Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
| | - S C Webster
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom
| | - E D Standing
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom
| | - A Rodriguez
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom
| | - A E Webb
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom
| | - B Lekitsch
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom
| | - W K Hensinger
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom
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15
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Green TJ, Biercuk MJ. Phase-modulated decoupling and error suppression in qubit-oscillator systems. PHYSICAL REVIEW LETTERS 2015; 114:120502. [PMID: 25860726 DOI: 10.1103/physrevlett.114.120502] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Indexed: 06/04/2023]
Abstract
We present a scheme designed to suppress the dominant source of infidelity in entangling gates between quantum systems coupled through intermediate bosonic oscillator modes. Such systems are particularly susceptible to residual qubit-oscillator entanglement at the conclusion of a gate period that reduces the fidelity of the target entangling operation. We demonstrate how the exclusive use of discrete shifts in the phase of the field moderating the qubit-oscillator interaction is sufficient to both ensure multiple oscillator modes are decoupled and to suppress the effects of fluctuations in the driving field. This approach is amenable to a wide variety of technical implementations including geometric phase gates in superconducting qubits and the Molmer-Sorensen gate for trapped ions. We present detailed example protocols tailored to trapped-ion experiments and demonstrate that our approach has the potential to enable multiqubit gate implementation with a significant reduction in technical complexity relative to previously demonstrated protocols.
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Affiliation(s)
- Todd J Green
- ARC Centre for Engineered Quantum Systems, School of Physics, The University of Sydney, New South Wales 2006 Australia
| | - Michael J Biercuk
- ARC Centre for Engineered Quantum Systems, School of Physics, The University of Sydney, New South Wales 2006 Australia
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16
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Tunable spin-spin interactions and entanglement of ions in separate potential wells. Nature 2014; 512:57-60. [PMID: 25100480 DOI: 10.1038/nature13565] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 06/02/2014] [Indexed: 11/09/2022]
Abstract
Quantum simulation--the use of one quantum system to simulate a less controllable one--may provide an understanding of the many quantum systems which cannot be modelled using classical computers. Considerable progress in control and manipulation has been achieved for various quantum systems, but one of the remaining challenges is the implementation of scalable devices. In this regard, individual ions trapped in separate tunable potential wells are promising. Here we implement the basic features of this approach and demonstrate deterministic tuning of the Coulomb interaction between two ions, independently controlling their local wells. The scheme is suitable for emulating a range of spin-spin interactions, but to characterize the performance of our set-up we select one that entangles the internal states of the two ions with a fidelity of 0.82(1) (the digit in parentheses shows the standard error of the mean). Extension of this building block to a two-dimensional network, which is possible using ion-trap microfabrication processes, may provide a new quantum simulator architecture with broad flexibility in designing and scaling the arrangement of ions and their mutual interactions. To perform useful quantum simulations, including those of condensed-matter phenomena such as the fractional quantum Hall effect, an array of tens of ions might be sufficient.
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17
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Choi T, Debnath S, Manning TA, Figgatt C, Gong ZX, Duan LM, Monroe C. Optimal quantum control of multimode couplings between trapped ion qubits for scalable entanglement. PHYSICAL REVIEW LETTERS 2014; 112:190502. [PMID: 24877921 DOI: 10.1103/physrevlett.112.190502] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Indexed: 06/03/2023]
Abstract
We demonstrate entangling quantum gates within a chain of five trapped ion qubits by optimally shaping optical fields that couple to multiple collective modes of motion. We individually address qubits with segmented optical pulses to construct multipartite entangled states in a programmable way. This approach enables high-fidelity gates that can be scaled to larger qubit registers for quantum computation and simulation.
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Affiliation(s)
- T Choi
- Joint Quantum Institute, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, Maryland 20742, USA
| | - S Debnath
- Joint Quantum Institute, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, Maryland 20742, USA
| | - T A Manning
- Joint Quantum Institute, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, Maryland 20742, USA
| | - C Figgatt
- Joint Quantum Institute, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, Maryland 20742, USA
| | - Z-X Gong
- Joint Quantum Institute, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, Maryland 20742, USA and Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - L-M Duan
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - C Monroe
- Joint Quantum Institute, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, Maryland 20742, USA
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18
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Time-resolved magnetic sensing with electronic spins in diamond. Nat Commun 2014; 5:3141. [DOI: 10.1038/ncomms4141] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2013] [Accepted: 12/18/2013] [Indexed: 01/05/2023] Open
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19
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Khodjasteh K, Sastrawan J, Hayes D, Green TJ, Biercuk MJ, Viola L. Designing a practical high-fidelity long-time quantum memory. Nat Commun 2013; 4:2045. [PMID: 23784079 DOI: 10.1038/ncomms3045] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Accepted: 05/23/2013] [Indexed: 11/09/2022] Open
Abstract
Quantum memory is a central component for quantum information processing devices, and will be required to provide high-fidelity storage of arbitrary states, long storage times and small access latencies. Despite growing interest in applying physical-layer error-suppression strategies to boost fidelities, it has not previously been possible to meet such competing demands with a single approach. Here we use an experimentally validated theoretical framework to identify periodic repetition of a high-order dynamical decoupling sequence as a systematic strategy to meet these challenges. We provide analytic bounds-validated by numerical calculations-on the characteristics of the relevant control sequences and show that a 'stroboscopic saturation' of coherence, or coherence plateau, can be engineered, even in the presence of experimental imperfection. This permits high-fidelity storage for times that can be exceptionally long, meaning that our device-independent results should prove instrumental in producing practically useful quantum technologies.
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Affiliation(s)
- Kaveh Khodjasteh
- Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, New Hampshire 03755, USA
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20
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Gamouras A, Mathew R, Freisem S, Deppe DG, Hall KC. Simultaneous deterministic control of distant qubits in two semiconductor quantum dots. NANO LETTERS 2013; 13:4666-4670. [PMID: 24001027 DOI: 10.1021/nl4018176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
In optimal quantum control (OQC), a target quantum state of matter is achieved by tailoring the phase and amplitude of the control Hamiltonian through femtosecond pulse-shaping techniques and powerful adaptive feedback algorithms. Motivated by recent applications of OQC in quantum information science as an approach to optimizing quantum gates in atomic and molecular systems, here we report the experimental implementation of OQC in a solid-state system consisting of distinguishable semiconductor quantum dots. We demonstrate simultaneous high-fidelity π and 2π single qubit gates in two different quantum dots using a single engineered infrared femtosecond pulse. These experiments enhance the scalability of semiconductor-based quantum hardware and lay the foundation for applications of pulse shaping to optimize quantum gates in other solid-state systems.
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Affiliation(s)
- A Gamouras
- Department of Physics and Atmospheric Science, Dalhousie University , Halifax, Nova Scotia B3H4R2, Canada
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21
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Tan TR, Gaebler JP, Bowler R, Lin Y, Jost JD, Leibfried D, Wineland DJ. Demonstration of a dressed-state phase gate for trapped ions. PHYSICAL REVIEW LETTERS 2013; 110:263002. [PMID: 23848869 DOI: 10.1103/physrevlett.110.263002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Indexed: 06/02/2023]
Abstract
We demonstrate a trapped-ion entangling-gate scheme proposed by Bermudez et al. [Phys. Rev. A 85, 040302 (2012)]. Simultaneous excitation of a strong carrier and a single-sideband transition enables deterministic creation of entangled states. The method works for magnetic field-insensitive states, is robust against thermal excitations, includes dynamical decoupling from qubit dephasing errors, and provides simplifications in experimental implementation compared to some other entangling gates with trapped ions. We achieve a Bell state fidelity of 0.974(4) and identify the main sources of error.
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Affiliation(s)
- T R Tan
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA.
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22
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Piltz C, Scharfenberger B, Khromova A, Varón AF, Wunderlich C. Protecting conditional quantum gates by robust dynamical decoupling. PHYSICAL REVIEW LETTERS 2013; 110:200501. [PMID: 25167390 DOI: 10.1103/physrevlett.110.200501] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Indexed: 06/03/2023]
Abstract
Dephasing--phase randomization of a quantum superposition state--is a major obstacle for the realization of high fidelity quantum logic operations. Here, we implement a two-qubit controlled-NOT gate using dynamical decoupling (DD), despite the gate time being more than 1 order of magnitude longer than the intrinsic coherence time of the system. For realizing this universal conditional quantum gate, we have devised a concatenated DD sequence that ensures robustness against imperfections of DD pulses that otherwise may destroy quantum information or interfere with gate dynamics. We compare its performance with three other types of DD sequences. These experiments are carried out using a well-controlled prototype quantum system--trapped atomic ions coupled by an effective spin-spin interaction. The scheme for protecting conditional quantum gates demonstrated here is applicable to other physical systems, such as nitrogen vacancy centers, solid state nuclear magnetic resonance, and circuit quantum electrodynamics.
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Affiliation(s)
- Ch Piltz
- Department Physik, Naturwissenschaftlich-Technische Fakultät, Universität Siegen, 57068 Siegen, Germany
| | - B Scharfenberger
- Department Physik, Naturwissenschaftlich-Technische Fakultät, Universität Siegen, 57068 Siegen, Germany
| | - A Khromova
- Department Physik, Naturwissenschaftlich-Technische Fakultät, Universität Siegen, 57068 Siegen, Germany
| | - A F Varón
- Department Physik, Naturwissenschaftlich-Technische Fakultät, Universität Siegen, 57068 Siegen, Germany
| | - Ch Wunderlich
- Department Physik, Naturwissenschaftlich-Technische Fakultät, Universität Siegen, 57068 Siegen, Germany
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