1
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Huang JY, Su RY, Lim WH, Feng M, van Straaten B, Severin B, Gilbert W, Dumoulin Stuyck N, Tanttu T, Serrano S, Cifuentes JD, Hansen I, Seedhouse AE, Vahapoglu E, Leon RCC, Abrosimov NV, Pohl HJ, Thewalt MLW, Hudson FE, Escott CC, Ares N, Bartlett SD, Morello A, Saraiva A, Laucht A, Dzurak AS, Yang CH. High-fidelity spin qubit operation and algorithmic initialization above 1 K. Nature 2024; 627:772-777. [PMID: 38538941 PMCID: PMC10972758 DOI: 10.1038/s41586-024-07160-2] [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: 08/18/2023] [Accepted: 02/05/2024] [Indexed: 04/01/2024]
Abstract
The encoding of qubits in semiconductor spin carriers has been recognized as a promising approach to a commercial quantum computer that can be lithographically produced and integrated at scale1-10. However, the operation of the large number of qubits required for advantageous quantum applications11-13 will produce a thermal load exceeding the available cooling power of cryostats at millikelvin temperatures. As the scale-up accelerates, it becomes imperative to establish fault-tolerant operation above 1 K, at which the cooling power is orders of magnitude higher14-18. Here we tune up and operate spin qubits in silicon above 1 K, with fidelities in the range required for fault-tolerant operations at these temperatures19-21. We design an algorithmic initialization protocol to prepare a pure two-qubit state even when the thermal energy is substantially above the qubit energies and incorporate radiofrequency readout to achieve fidelities up to 99.34% for both readout and initialization. We also demonstrate single-qubit Clifford gate fidelities up to 99.85% and a two-qubit gate fidelity of 98.92%. These advances overcome the fundamental limitation that the thermal energy must be well below the qubit energies for the high-fidelity operation to be possible, surmounting a main obstacle in the pathway to scalable and fault-tolerant quantum computation.
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Affiliation(s)
- Jonathan Y Huang
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia.
| | - Rocky Y Su
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
| | - Wee Han Lim
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
- Diraq, Sydney, New South Wales, Australia
| | - MengKe Feng
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
| | | | - Brandon Severin
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
- Department of Engineering Science, University of Oxford, Oxford, UK
| | - Will Gilbert
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
- Diraq, Sydney, New South Wales, Australia
| | - Nard Dumoulin Stuyck
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
- Diraq, Sydney, New South Wales, Australia
| | - Tuomo Tanttu
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
- Diraq, Sydney, New South Wales, Australia
| | - Santiago Serrano
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
| | - Jesus D Cifuentes
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
| | - Ingvild Hansen
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
| | - Amanda E Seedhouse
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
| | - Ensar Vahapoglu
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
- Diraq, Sydney, New South Wales, Australia
| | - Ross C C Leon
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
- Quantum Motion Technologies, London, UK
| | | | | | - Michael L W Thewalt
- Department of Physics, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Fay E Hudson
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
- Diraq, Sydney, New South Wales, Australia
| | - Christopher C Escott
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
- Diraq, Sydney, New South Wales, Australia
| | - Natalia Ares
- Department of Engineering Science, University of Oxford, Oxford, UK
| | - Stephen D Bartlett
- Centre for Engineered Quantum Systems, School of Physics, University of Sydney, Sydney, New South Wales, Australia
| | - Andrea Morello
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
| | - Andre Saraiva
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
- Diraq, Sydney, New South Wales, Australia
| | - Arne Laucht
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
- Diraq, Sydney, New South Wales, Australia
| | - Andrew S Dzurak
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia.
- Diraq, Sydney, New South Wales, Australia.
| | - Chih Hwan Yang
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia.
- Diraq, Sydney, New South Wales, Australia.
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2
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Zhang B, Xue Y, Park HS, Jiang JW. Flexible nanomechanical bit based on few-layer graphene. Phys Chem Chem Phys 2024; 26:822-829. [PMID: 38095185 DOI: 10.1039/d3cp03241h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2024]
Abstract
Mechanical computers have gained intense research interest at size scales ranging from nano to macro as they may complement electronic computers operating in extreme environments. While nanoscale mechanical computers may be easier to integrate with traditional electronic components, most current nanomechanical computers are based on volatile resonator systems that require continuous energy input. In this study, we propose a non-volatile nanomechanical bit based on the quasi-stable configurations of few-layer graphene with void defects, and demonstrate its multiple quasi-stable states by deriving an analytic relationship for the void configuration based on a competition between the bending energy and the cohesive energy. Using this nanomechanical bit, typical logic gates are constructed to perform Boolean calculations, including NOT, AND, OR, NAND and NOR gates, and demonstrate reprogrammability between these logic gates. We also study the accuracy and the stability of the nanomechanical bits based on the few-layer graphene. These findings provide a novel approach to realize the nanomechanical computing process.
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Affiliation(s)
- Bin Zhang
- Shanghai Key Laboratory of Mechanics in Energy Engineering, Shanghai Institute of Applied Mathematics and Mechanics, Shanghai Frontier Science Center of Mechanoinformatics, School of Mechanics and Engineering Science, Shanghai University, Shanghai 200072, People's Republic of China.
| | - Yixuan Xue
- Shanghai Key Laboratory of Mechanics in Energy Engineering, Shanghai Institute of Applied Mathematics and Mechanics, Shanghai Frontier Science Center of Mechanoinformatics, School of Mechanics and Engineering Science, Shanghai University, Shanghai 200072, People's Republic of China.
| | - Harold S Park
- Department of Mechanical Engineering, Boston University, Boston, Massachusetts 02215, USA
| | - Jin-Wu Jiang
- Shanghai Key Laboratory of Mechanics in Energy Engineering, Shanghai Institute of Applied Mathematics and Mechanics, Shanghai Frontier Science Center of Mechanoinformatics, School of Mechanics and Engineering Science, Shanghai University, Shanghai 200072, People's Republic of China.
- Zhejiang Laboratory, Hangzhou 311100, China
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3
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Paesani S, Brown BJ. High-Threshold Quantum Computing by Fusing One-Dimensional Cluster States. PHYSICAL REVIEW LETTERS 2023; 131:120603. [PMID: 37802959 DOI: 10.1103/physrevlett.131.120603] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 07/11/2023] [Indexed: 10/08/2023]
Abstract
We propose a measurement-based model for fault-tolerant quantum computation that can be realized with one-dimensional cluster states and fusion measurements only; basic resources that are readily available with scalable photonic hardware. Our simulations demonstrate high thresholds compared with other measurement-based models realized with basic entangled resources and 2-qubit fusion measurements. Its high tolerance to noise indicates that our practical construction offers a promising route to scalable quantum computing with quantum emitters and linear-optical elements.
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Affiliation(s)
- Stefano Paesani
- Center for Hybrid Quantum Networks (Hy-Q), Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, Copenhagen 2100, Denmark
- NNF Quantum Computing Programme, Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, Copenhagen 2100, Denmark
| | - Benjamin J Brown
- IBM Quantum, T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
- IBM Denmark, Prøvensvej 1, Brøndby 2605, Denmark
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4
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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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5
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Fellner M, Messinger A, Ender K, Lechner W. Universal Parity Quantum Computing. PHYSICAL REVIEW LETTERS 2022; 129:180503. [PMID: 36374683 DOI: 10.1103/physrevlett.129.180503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 09/16/2022] [Indexed: 06/16/2023]
Abstract
We propose a universal gate set for quantum computing with all-to-all connectivity and intrinsic robustness to bit-flip errors based on parity encoding. We show that logical controlled phase gate and R_{z} rotations can be implemented in parity encoding with single-qubit operations. Together with logical R_{x} rotations, implemented via nearest-neighbor controlled-NOT gates and an R_{x} rotation, these form a universal gate set. As the controlled phase gate requires only single-qubit rotations, the proposed scheme has advantages for several cornerstone quantum algorithms, e.g., the quantum Fourier transform. We present a method to switch between different encoding variants via partial on-the-fly encoding and decoding.
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Affiliation(s)
- Michael Fellner
- Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck, Austria
- Parity Quantum Computing GmbH, A-6020 Innsbruck, Austria
| | | | - Kilian Ender
- Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck, Austria
- Parity Quantum Computing GmbH, A-6020 Innsbruck, Austria
| | - Wolfgang Lechner
- Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck, Austria
- Parity Quantum Computing GmbH, A-6020 Innsbruck, Austria
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6
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Dynamic compensation of stray electric fields in an ion trap using machine learning and adaptive algorithm. Sci Rep 2022; 12:7067. [PMID: 35487938 PMCID: PMC9054784 DOI: 10.1038/s41598-022-11142-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 04/08/2022] [Indexed: 11/08/2022] Open
Abstract
Surface ion traps are among the most promising technologies for scaling up quantum computing machines, but their complicated multi-electrode geometry can make some tasks, including compensation for stray electric fields, challenging both at the level of modeling and of practical implementation. Here we demonstrate the compensation of stray electric fields using a gradient descent algorithm and a machine learning technique, which trained a deep learning network. We show automated dynamical compensation tested against induced electric charging from UV laser light hitting the chip trap surface. The results show improvement in compensation using gradient descent and the machine learner over manual compensation. This improvement is inferred from an increase of the fluorescence rate of 78% and 96% respectively, for a trapped [Formula: see text]Yb[Formula: see text] ion driven by a laser tuned to [Formula: see text] MHz of the [Formula: see text]S[Formula: see text]P[Formula: see text] Doppler cooling transition at 369.5 nm.
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7
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Quantum Computing With Trapped Ions: An Overview. IEEE NANOTECHNOLOGY MAGAZINE 2022. [DOI: 10.1109/mnano.2022.3175384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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8
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Abstract
Mechanical mechanisms have been used to process information for millennia, with famous examples ranging from the Antikythera mechanism of the Ancient Greeks to the analytical machines of Charles Babbage. More recently, electronic forms of computation and information processing have overtaken these mechanical forms, owing to better potential for miniaturization and integration. However, several unconventional computing approaches have recently been introduced, which blend ideas of information processing, materials science and robotics. This has raised the possibility of new mechanical computing systems that augment traditional electronic computing by interacting with and adapting to their environment. Here we discuss the use of mechanical mechanisms, and associated nonlinearities, as a means of processing information, with a view towards a framework in which adaptable materials and structures act as a distributed information processing network, even enabling information processing to be viewed as a material property, alongside traditional material properties such as strength and stiffness. We focus on approaches to abstract digital logic in mechanical systems, discuss how these systems differ from traditional electronic computing, and highlight the challenges and opportunities that they present.
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9
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Wang J, Shen L, Zhou W. A bibliometric analysis of quantum computing literature: mapping and evidences from scopus. TECHNOLOGY ANALYSIS & STRATEGIC MANAGEMENT 2021. [DOI: 10.1080/09537325.2021.1963429] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Jiaxing Wang
- College of Computer Science, Zhejiang University of Technology, Hangzhou, People’s Republic of China
| | - Lihua Shen
- The Library of Zhejiang University, Hangzhou, People’s Republic of China
| | - Wuyuan Zhou
- Zhejiang Academy of Science and Technology Information, Hangzhou, People’s Republic of China
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10
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Vahapoglu E, Slack-Smith JP, Leon RCC, Lim WH, Hudson FE, Day T, Tanttu T, Yang CH, Laucht A, Dzurak AS, Pla JJ. Single-electron spin resonance in a nanoelectronic device using a global field. SCIENCE ADVANCES 2021; 7:7/33/eabg9158. [PMID: 34389538 PMCID: PMC8363148 DOI: 10.1126/sciadv.abg9158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 06/23/2021] [Indexed: 06/13/2023]
Abstract
Spin-based silicon quantum electronic circuits offer a scalable platform for quantum computation, combining the manufacturability of semiconductor devices with the long coherence times afforded by spins in silicon. Advancing from current few-qubit devices to silicon quantum processors with upward of a million qubits, as required for fault-tolerant operation, presents several unique challenges, one of the most demanding being the ability to deliver microwave signals for large-scale qubit control. Here, we demonstrate a potential solution to this problem by using a three-dimensional dielectric resonator to broadcast a global microwave signal across a quantum nanoelectronic circuit. Critically, this technique uses only a single microwave source and is capable of delivering control signals to millions of qubits simultaneously. We show that the global field can be used to perform spin resonance of single electrons confined in a silicon double quantum dot device, establishing the feasibility of this approach for scalable spin qubit control.
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Affiliation(s)
- Ensar Vahapoglu
- School of Electrical Engineering and Telecommunications, UNSW Sydney, Sydney, NSW 2052, Australia.
| | - James P Slack-Smith
- School of Electrical Engineering and Telecommunications, UNSW Sydney, Sydney, NSW 2052, Australia.
| | - Ross C C Leon
- School of Electrical Engineering and Telecommunications, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Wee Han Lim
- School of Electrical Engineering and Telecommunications, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Fay E Hudson
- School of Electrical Engineering and Telecommunications, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Tom Day
- School of Electrical Engineering and Telecommunications, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Tuomo Tanttu
- School of Electrical Engineering and Telecommunications, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Chih Hwan Yang
- School of Electrical Engineering and Telecommunications, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Arne Laucht
- School of Electrical Engineering and Telecommunications, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Andrew S Dzurak
- School of Electrical Engineering and Telecommunications, UNSW Sydney, Sydney, NSW 2052, Australia.
| | - Jarryd J Pla
- School of Electrical Engineering and Telecommunications, UNSW Sydney, Sydney, NSW 2052, Australia.
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11
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Quantum computer based on shuttling trapped ions. Nature 2021; 592:190-191. [PMID: 33828312 DOI: 10.1038/d41586-021-00844-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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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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Gao S, Hughes WJ, Lucas DM, Ballance TG, Goodwin JF. An optically heated atomic source for compact ion trap vacuum systems. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:033205. [PMID: 33820060 DOI: 10.1063/5.0038162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 02/16/2021] [Indexed: 06/12/2023]
Abstract
We present a design for an atomic oven suitable for loading ion traps, which is operated via optical heating with a continuous-wave multimode diode laser. The absence of the low-resistance electrical connections necessary for Joule heating allows the oven to be extremely well thermally isolated from the rest of the vacuum system. Extrapolating from high-flux measurements of an oven filled with calcium, we calculate that a target region number density of 100 cm-3, suitable for rapid ion loading, will be produced with 175(10) mW of heating laser power, limited by radiative losses. With simple feedforward to the laser power, the turn-on time for the oven is 15 s. Our measurements indicate that an oven volume 1000 times smaller could still hold enough source metal for decades of continuous operation.
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Affiliation(s)
- S Gao
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Rd., Oxford OX1 3PU, United Kingdom
| | - W J Hughes
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Rd., Oxford OX1 3PU, United Kingdom
| | - D M Lucas
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Rd., Oxford OX1 3PU, United Kingdom
| | - T G Ballance
- ColdQuanta UK, Oxford Centre for Innovation, Oxford OX1 1BY, United Kingdom
| | - J F Goodwin
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Rd., Oxford OX1 3PU, United Kingdom
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14
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Park Y, Jung C, Seong M, Lee M, Cho DD, Kim T. A New Measurement Method for High Voltages Applied to an Ion Trap Generated by an RF Resonator. SENSORS 2021; 21:s21041143. [PMID: 33562053 PMCID: PMC7914741 DOI: 10.3390/s21041143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/18/2021] [Accepted: 02/04/2021] [Indexed: 11/25/2022]
Abstract
A new method is proposed to measure unknown amplitudes of radio frequency (RF) voltages applied to ion traps, using a pre-calibrated voltage divider with RF shielding. In contrast to previous approaches that estimate the applied voltage by comparing the measured secular frequencies with a numerical simulation, we propose using a pre-calibrated voltage divider to determine the absolute amplitude of large RF voltages amplified by a helical resonator. The proposed method does not require measurement of secular frequencies and completely removes uncertainty caused by limitations of numerical simulations. To experimentally demonstrate our method, we first obtained a functional relation between measured secular frequencies and large amplitudes of RF voltages using the calibrated voltage divider. A comparison of measured relations and simulation results without any fitting parameters confirmed the validity of the proposed method. Our method can be applied to most ion trap experiments. In particular, it will be an essential tool for surface ion traps which are extremely vulnerable to unknown large RF voltages and for improving the accuracy of numerical simulations for ion trap experiments.
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Affiliation(s)
- Yunjae Park
- Department of Electrical and Computer Engineering, Seoul National University, Seoul 08826, Korea; (Y.P.); (C.J.); (M.L.); (D.D.C.)
- Automation and Systems Research Institute, Seoul National University, Seoul 08826, Korea
- Inter-University Semiconductor Research Center, Seoul National University, Seoul 08826, Korea
| | - Changhyun Jung
- Department of Electrical and Computer Engineering, Seoul National University, Seoul 08826, Korea; (Y.P.); (C.J.); (M.L.); (D.D.C.)
- Automation and Systems Research Institute, Seoul National University, Seoul 08826, Korea
- Inter-University Semiconductor Research Center, Seoul National University, Seoul 08826, Korea
| | - Myeongseok Seong
- Department of Mechanical Engineering, Seoul National University, Seoul 08826, Korea;
| | - Minjae Lee
- Department of Electrical and Computer Engineering, Seoul National University, Seoul 08826, Korea; (Y.P.); (C.J.); (M.L.); (D.D.C.)
- Automation and Systems Research Institute, Seoul National University, Seoul 08826, Korea
- Inter-University Semiconductor Research Center, Seoul National University, Seoul 08826, Korea
| | - Dongil Dan Cho
- Department of Electrical and Computer Engineering, Seoul National University, Seoul 08826, Korea; (Y.P.); (C.J.); (M.L.); (D.D.C.)
- Automation and Systems Research Institute, Seoul National University, Seoul 08826, Korea
- Inter-University Semiconductor Research Center, Seoul National University, Seoul 08826, Korea
| | - Taehyun Kim
- Automation and Systems Research Institute, Seoul National University, Seoul 08826, Korea
- Inter-University Semiconductor Research Center, Seoul National University, Seoul 08826, Korea
- Department of Computer Science and Engineering, Seoul National University, Seoul 08826, Korea
- Institute of Computer Technology, Seoul National University, Seoul 08826, Korea
- Correspondence: ; Tel.: +82-2-880-1725
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15
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Wang P, Luan CY, Qiao M, Um M, Zhang J, Wang Y, Yuan X, Gu M, Zhang J, Kim K. Single ion qubit with estimated coherence time exceeding one hour. Nat Commun 2021; 12:233. [PMID: 33431845 PMCID: PMC7801401 DOI: 10.1038/s41467-020-20330-w] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 11/24/2020] [Indexed: 11/08/2022] Open
Abstract
Realizing a long coherence time quantum memory is a major challenge of current quantum technology. Until now, the longest coherence-time of a single qubit was reported as 660 s in a single 171Yb+ ion-qubit through the technical developments of sympathetic cooling and dynamical decoupling pulses, which addressed heating-induced detection inefficiency and magnetic field fluctuations. However, it was not clear what prohibited further enhancement. Here, we identify and suppress the limiting factors, which are the remaining magnetic-field fluctuations, frequency instability and leakage of the microwave reference-oscillator. Then, we observe the coherence time of around 5500 s for the 171Yb+ ion-qubit, which is the time constant of the exponential decay fit from the measurements up to 960 s. We also systematically study the decoherence process of the quantum memory by using quantum process tomography and analyze the results by applying recently developed resource theories of quantum memory and coherence. Our experimental demonstration will accelerate practical applications of quantum memories for various quantum information processing, especially in the noisy-intermediate-scale quantum regime.
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Affiliation(s)
- Pengfei Wang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, 100084, Beijing, China.
| | - Chun-Yang Luan
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, 100084, Beijing, China
| | - Mu Qiao
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, 100084, Beijing, China
| | - Mark Um
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, 100084, Beijing, China
| | - Junhua Zhang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, 100084, Beijing, China
- Shenzhen Institute for Quantum Science and Engineering, and Department of Physics, Southern University of Science and Technology, 518055, Shenzhen, P. R. China
| | - Ye Wang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, 100084, Beijing, China
- Department of Electrical and Computer Engineering, Duke University, Durham, NC, 27708, USA
| | - Xiao Yuan
- Stanford Institute for Theoretical Physics, Stanford University, Stanford, CA, 94305, USA
- Center on Frontiers of Computing Studies, Department of Computer Science, Peking University, Beijing, 100871, China
| | - Mile Gu
- Centre for Quantum Technologies, National University of Singapore, Singapore, 117543, Singapore
- School of Mathematical and Physical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
- Complexity Institute, Nanyang Technological University, Singapore, 637335, Singapore
| | - Jingning Zhang
- Beijing Academy of Quantum Information Sciences, 100193, Beijing, China
| | - Kihwan Kim
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, 100084, Beijing, China.
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16
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Entangling logical qubits with lattice surgery. Nature 2021; 589:220-224. [PMID: 33442044 DOI: 10.1038/s41586-020-03079-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 10/20/2020] [Indexed: 01/29/2023]
Abstract
The development of quantum computing architectures from early designs and current noisy devices to fully fledged quantum computers hinges on achieving fault tolerance using quantum error correction1-4. However, these correction capabilities come with an overhead for performing the necessary fault-tolerant logical operations on logical qubits (qubits that are encoded in ensembles of physical qubits and protected by error-correction codes)5-8. One of the most resource-efficient ways to implement logical operations is lattice surgery9-11, where groups of physical qubits, arranged on lattices, can be merged and split to realize entangling gates and teleport logical information. Here we report the experimental realization of lattice surgery between two qubits protected via a topological error-correction code in a ten-qubit ion-trap quantum information processor. In this system, we can carry out the necessary quantum non-demolition measurements through a series of local and entangling gates, as well as measurements on auxiliary qubits. In particular, we demonstrate entanglement between two logical qubits and we implement logical state teleportation between them. The demonstration of these operations-fundamental building blocks for quantum computation-through lattice surgery represents a step towards the efficient realization of fault-tolerant quantum computation.
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17
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Hassanzadeh P. Towards the quantum-enabled technologies for development of drugs or delivery systems. J Control Release 2020; 324:260-279. [DOI: 10.1016/j.jconrel.2020.04.050] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Revised: 04/28/2020] [Accepted: 04/29/2020] [Indexed: 12/20/2022]
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18
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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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19
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Kim Y, Teo YS, Ahn D, Im DG, Cho YW, Leuchs G, Sánchez-Soto LL, Jeong H, Kim YH. Universal Compressive Characterization of Quantum Dynamics. PHYSICAL REVIEW LETTERS 2020; 124:210401. [PMID: 32530676 DOI: 10.1103/physrevlett.124.210401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Accepted: 04/27/2020] [Indexed: 06/11/2023]
Abstract
Recent quantum technologies utilize complex multidimensional processes that govern the dynamics of quantum systems. We develop an adaptive diagonal-element-probing compression technique that feasibly characterizes any unknown quantum processes using much fewer measurements compared to conventional methods. This technique utilizes compressive projective measurements that are generalizable to an arbitrary number of subsystems. Both numerical analysis and experimental results with unitary gates demonstrate low measurement costs, of order O(d^{2}) for d-dimensional systems, and robustness against statistical noise. Our work potentially paves the way for a reliable and highly compressive characterization of general quantum devices.
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Affiliation(s)
- Yosep Kim
- Department of Physics, Pohang University of Science and Technology (POSTECH), 37673 Pohang, Korea
| | - Yong Siah Teo
- Department of Physics and Astronomy, Seoul National University, 08826 Seoul, Korea
| | - Daekun Ahn
- Department of Physics and Astronomy, Seoul National University, 08826 Seoul, Korea
| | - Dong-Gil Im
- Department of Physics, Pohang University of Science and Technology (POSTECH), 37673 Pohang, Korea
| | - Young-Wook Cho
- Center for Quantum Information, Korea Institute of Science and Technology (KIST), 02792 Seoul, Korea
| | - Gerd Leuchs
- Max-Planck-Institut für die Physik des Lichts, Staudtstraße 2, 91058 Erlangen, Germany
- Institute of Applied Physics, Russian Academy of Sciences, 603950 Nizhny Novgorod, Russia
| | - Luis L Sánchez-Soto
- Max-Planck-Institut für die Physik des Lichts, Staudtstraße 2, 91058 Erlangen, Germany
- Departamento de Óptica, Facultad de Física, Universidad Complutense, 28040 Madrid, Spain
| | - Hyunseok Jeong
- Department of Physics and Astronomy, Seoul National University, 08826 Seoul, Korea
| | - Yoon-Ho Kim
- Department of Physics, Pohang University of Science and Technology (POSTECH), 37673 Pohang, Korea
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20
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21
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Kulkarni A, Bindal N, Kaushik BK. Quantum Computing Circuits Based on Spin-Torque Qubit Architecture: Toward the Physical Realization of Quantum Computers. IEEE NANOTECHNOLOGY MAGAZINE 2019. [DOI: 10.1109/mnano.2019.2927782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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22
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Oh C, Teo YS, Jeong H. Probing Bayesian Credible Regions Intrinsically: A Feasible Error Certification for Physical Systems. PHYSICAL REVIEW LETTERS 2019; 123:040602. [PMID: 31491280 DOI: 10.1103/physrevlett.123.040602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Revised: 06/20/2019] [Indexed: 06/10/2023]
Abstract
Standard computation of size and credibility of a Bayesian credible region for certifying any point estimator of an unknown parameter (such as a quantum state, channel, phase, etc.) requires selecting points that are in the region from a finite parameter-space sample, which is infeasible for a large dataset or dimension as the region would then be extremely small. We solve this problem by introducing the in-region sampling theory to compute both region qualities just by sampling appropriate functions over the region itself using any Monte Carlo sampling method. We take in-region sampling to the next level by understanding the credible-region capacity (an alternative description for the region content to size) as the average l_{p}-norm distance (p>0) between a random region point and the estimator, and present analytical formulas for p=2 to estimate both the capacity and credibility for any dimension and a sufficiently large dataset without Monte Carlo sampling, thereby providing a quick alternative to Bayesian certification. All results are discussed in the context of quantum-state tomography.
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Affiliation(s)
- Changhun Oh
- Department of Physics and Astronomy, Seoul National University, 08826 Seoul, Korea
| | - Yong Siah Teo
- Department of Physics and Astronomy, Seoul National University, 08826 Seoul, Korea
| | - Hyunseok Jeong
- Department of Physics and Astronomy, Seoul National University, 08826 Seoul, Korea
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23
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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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24
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Zwolak JP, Kalantre SS, Wu X, Ragole S, Taylor JM. QFlow lite dataset: A machine-learning approach to the charge states in quantum dot experiments. PLoS One 2018; 13:e0205844. [PMID: 30332463 PMCID: PMC6192646 DOI: 10.1371/journal.pone.0205844] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 09/25/2018] [Indexed: 11/18/2022] Open
Abstract
Background Over the past decade, machine learning techniques have revolutionized how research and science are done, from designing new materials and predicting their properties to data mining and analysis to assisting drug discovery to advancing cybersecurity. Recently, we added to this list by showing how a machine learning algorithm (a so-called learner) combined with an optimization routine can assist experimental efforts in the realm of tuning semiconductor quantum dot (QD) devices. Among other applications, semiconductor quantum dots are a candidate system for building quantum computers. In order to employ QDs, one needs to tune the devices into a desirable configuration suitable for quantum computing. While current experiments adjust the control parameters heuristically, such an approach does not scale with the increasing size of the quantum dot arrays required for even near-term quantum computing demonstrations. Establishing a reliable protocol for tuning QD devices that does not rely on the gross-scale heuristics developed by experimentalists is thus of great importance. Materials and methods To implement the machine learning-based approach, we constructed a dataset of simulated QD device characteristics, such as the conductance and the charge sensor response versus the applied electrostatic gate voltages. The gate voltages are the experimental ‘knobs’ for tuning the device into useful regimes. Here, we describe the methodology for generating the dataset, as well as its validation in training convolutional neural networks. Results and discussion From 200 training sets sampled randomly from the full dataset, we show that the learner’s accuracy in recognizing the state of a device is ≈ 96.5% when using either current-based or charge-sensor-based training. The spread in accuracy over our 200 training sets is 0.5% and 1.8% for current- and charge-sensor-based data, respectively. In addition, we also introduce a tool that enables other researchers to use this approach for further research: QFlow lite—a Python-based mini-software suite that uses the dataset to train neural networks to recognize the state of a device and differentiate between states in experimental data. This work gives the definitive reference for the new dataset that will help enable researchers to use it in their experiments or to develop new machine learning approaches and concepts.
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Affiliation(s)
- Justyna P. Zwolak
- Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD, 20742, United States of America
- National Institute of Standards and Technology, Gaithersburg, MD, 20899, United States of America
- * E-mail:
| | - Sandesh S. Kalantre
- Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD, 20742, United States of America
- National Institute of Standards and Technology, Gaithersburg, MD, 20899, United States of America
- Department of Physics, Indian Institute of Technology - Bombay, Mumbai, 400076, India
| | - Xingyao Wu
- Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD, 20742, United States of America
- Joint Quantum Institute, University of Maryland, College Park, MD, 20742, United States of America
| | - Stephen Ragole
- Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD, 20742, United States of America
- Joint Quantum Institute, University of Maryland, College Park, MD, 20742, United States of America
| | - Jacob M. Taylor
- Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD, 20742, United States of America
- National Institute of Standards and Technology, Gaithersburg, MD, 20899, United States of America
- Joint Quantum Institute, University of Maryland, College Park, MD, 20742, United States of America
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25
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An D, Matthiesen C, Abdelrahman A, Berlin-Udi M, Gorman D, Möller S, Urban E, Häffner H. Surface trap with dc-tunable ion-electrode distance. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:093102. [PMID: 30278688 DOI: 10.1063/1.5046527] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 08/14/2018] [Indexed: 06/08/2023]
Abstract
We describe the design, fabrication, and operation of a novel surface-electrode Paul trap that produces a radio-frequency-null along the axis perpendicular to the trap surface. This arrangement enables control of the vertical trapping potential and consequentially the ion-electrode distance via dc-electrodes only. We demonstrate the confinement of single 40Ca+ ions at heights between 50 μm and 300 μm above planar copper-coated aluminum electrodes. Laser-cooling and coherent operations are performed on both the planar and vertical motional modes. This architecture provides a platform for precision electric-field noise detection and trapping of vertical ion strings without excess micromotion and may have applications for scalable quantum computers with surface ion traps.
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Affiliation(s)
- Da An
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
| | - Clemens Matthiesen
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
| | - Ahmed Abdelrahman
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
| | - Maya Berlin-Udi
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
| | - Dylan Gorman
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
| | - Sönke Möller
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
| | - Erik Urban
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
| | - Hartmut Häffner
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
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26
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Bayat A, Alkurtass B, Sodano P, Johannesson H, Bose S. Measurement Quench in Many-Body Systems. PHYSICAL REVIEW LETTERS 2018; 121:030601. [PMID: 30085809 DOI: 10.1103/physrevlett.121.030601] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 05/09/2018] [Indexed: 06/08/2023]
Abstract
Measurement is one of the key concepts which discriminates classical and quantum physics. Unlike classical systems, a measurement on a quantum system typically alters it drastically as a result of wave function collapse. Here we suggest that this feature can be exploited for inducing quench dynamics in a many-body system while leaving its Hamiltonian unchanged. Importantly, by doing away with dedicated macroscopic devices for inducing a quench-using instead the indispensable measurement apparatus only-the protocol is expected to be easier to implement and more resilient against decoherence. By way of various case studies, we show that our scheme also has decisive advantages beyond reducing decoherence-for spectroscopy purposes and probing nonequilibrium scaling of critical and quantum impurity many-body systems.
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Affiliation(s)
- Abolfazl Bayat
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610051, China
- Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
| | - Bedoor Alkurtass
- Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
- Department of Physics and Astronomy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Pasquale Sodano
- International Institute of Physics, Universidade Federal do Rio Grande do Norte, 59078-400 Natal-RN, Brazil
| | - Henrik Johannesson
- Department of Physics, University of Gothenburg, SE 412 96 Gothenburg, Sweden
- Beijing Computational Science Research Center, Beijing 100094, China
| | - Sougato Bose
- Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
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27
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Li R, Petit L, Franke DP, Dehollain JP, Helsen J, Steudtner M, Thomas NK, Yoscovits ZR, Singh KJ, Wehner S, Vandersypen LMK, Clarke JS, Veldhorst M. A crossbar network for silicon quantum dot qubits. SCIENCE ADVANCES 2018; 4:eaar3960. [PMID: 29984303 PMCID: PMC6035036 DOI: 10.1126/sciadv.aar3960] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 05/29/2018] [Indexed: 05/31/2023]
Abstract
The spin states of single electrons in gate-defined quantum dots satisfy crucial requirements for a practical quantum computer. These include extremely long coherence times, high-fidelity quantum operation, and the ability to shuttle electrons as a mechanism for on-chip flying qubits. To increase the number of qubits to the thousands or millions of qubits needed for practical quantum information, we present an architecture based on shared control and a scalable number of lines. Crucially, the control lines define the qubit grid, such that no local components are required. Our design enables qubit coupling beyond nearest neighbors, providing prospects for nonplanar quantum error correction protocols. Fabrication is based on a three-layer design to define qubit and tunnel barrier gates. We show that a double stripline on top of the structure can drive high-fidelity single-qubit rotations. Self-aligned inhomogeneous magnetic fields induced by direct currents through superconducting gates enable qubit addressability and readout. Qubit coupling is based on the exchange interaction, and we show that parallel two-qubit gates can be performed at the detuning-noise insensitive point. While the architecture requires a high level of uniformity in the materials and critical dimensions to enable shared control, it stands out for its simplicity and provides prospects for large-scale quantum computation in the near future.
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Affiliation(s)
- Ruoyu Li
- QuTech, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
- Kavli Institute of Nanoscience, University of Technology, P.O. Box 5046, 2600 GA Delft, Netherlands
| | - Luca Petit
- QuTech, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
- Kavli Institute of Nanoscience, University of Technology, P.O. Box 5046, 2600 GA Delft, Netherlands
| | - David P. Franke
- QuTech, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
- Kavli Institute of Nanoscience, University of Technology, P.O. Box 5046, 2600 GA Delft, Netherlands
| | - Juan Pablo Dehollain
- QuTech, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
- Kavli Institute of Nanoscience, University of Technology, P.O. Box 5046, 2600 GA Delft, Netherlands
| | - Jonas Helsen
- QuTech, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
| | - Mark Steudtner
- QuTech, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
- Instituut-Lorentz, Universiteit Leiden, P.O. Box 9506, 2300 RA Leiden, Netherlands
| | - Nicole K. Thomas
- Components Research, Intel Corporation, 2501 Northwest 229th Avenue, Hillsboro, OR 97124, USA
| | - Zachary R. Yoscovits
- Components Research, Intel Corporation, 2501 Northwest 229th Avenue, Hillsboro, OR 97124, USA
| | - Kanwal J. Singh
- Components Research, Intel Corporation, 2501 Northwest 229th Avenue, Hillsboro, OR 97124, USA
| | - Stephanie Wehner
- QuTech, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
| | - Lieven M. K. Vandersypen
- QuTech, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
- Kavli Institute of Nanoscience, University of Technology, P.O. Box 5046, 2600 GA Delft, Netherlands
- Components Research, Intel Corporation, 2501 Northwest 229th Avenue, Hillsboro, OR 97124, USA
| | - James S. Clarke
- Components Research, Intel Corporation, 2501 Northwest 229th Avenue, Hillsboro, OR 97124, USA
| | - Menno Veldhorst
- QuTech, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
- Kavli Institute of Nanoscience, University of Technology, P.O. Box 5046, 2600 GA Delft, Netherlands
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28
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Abstract
The problem of the equilibrium triplet structures in fluids with quantum behavior is discussed. Theoretical questions of interest to the real space structures are addressed by studying the three types of structures that can be determined via path integrals (instantaneous, centroid, and total thermalized-continuous linear response). The cases of liquid para-H2 and liquid neon on their crystallization lines are examined with path-integral Monte Carlo simulations, the focus being on the instantaneous and the centroid triplet functions (equilateral and isosceles configurations). To analyze the results further, two standard closures, Kirkwood superposition and Jackson-Feenberg convolution, are utilized. In addition, some pilot calculations with path integrals and closures of the instantaneous triplet structure factor of liquid para-H2 are also carried out for the equilateral components. Triplet structural regularities connected to the pair radial structures are identified, a remarkable usefulness of the closures employed is observed (e.g., triplet spatial functions for medium-long distances, triplet structure factors for medium k wave numbers), and physical insight into the role of pair correlations near quantum crystallization is gained.
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Affiliation(s)
- Luis M Sesé
- Departamento de Ciencias y Técnicas Fisicoquímicas, Facultad de Ciencias, Universidad Nacional de Educación a Distancia, Paseo de la Senda del Rey 9, 28040 Madrid, Spain
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29
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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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30
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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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31
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Hong S, Lee M, Kwon YD, Cho DID, Kim T. Experimental Methods for Trapping Ions Using Microfabricated Surface Ion Traps. J Vis Exp 2017:56060. [PMID: 28872137 PMCID: PMC5614346 DOI: 10.3791/56060] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Ions trapped in a quadrupole Paul trap have been considered one of the strong physical candidates to implement quantum information processing. This is due to their long coherence time and their capability to manipulate and detect individual quantum bits (qubits). In more recent years, microfabricated surface ion traps have received more attention for large-scale integrated qubit platforms. This paper presents a microfabrication methodology for ion traps using micro-electro-mechanical system (MEMS) technology, including the fabrication method for a 14 µm-thick dielectric layer and metal overhang structures atop the dielectric layer. In addition, an experimental procedure for trapping ytterbium (Yb) ions of isotope 174 (174Yb+) using 369.5 nm, 399 nm, and 935 nm diode lasers is described. These methodologies and procedures involve many scientific and engineering disciplines, and this paper first presents the detailed experimental procedures. The methods discussed in this paper can easily be extended to the trapping of Yb ions of isotope 171 (171Yb+) and to the manipulation of qubits.
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Affiliation(s)
- Seokjun Hong
- ISRC/ASRI, Department of Electrical and Computer Engineering, Seoul National University
| | - Minjae Lee
- ISRC/ASRI, Department of Electrical and Computer Engineering, Seoul National University
| | | | - Dong-Il Dan Cho
- ISRC/ASRI, Department of Electrical and Computer Engineering, Seoul National University
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32
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Slichter DH, Verma VB, Leibfried D, Mirin RP, Nam SW, Wineland DJ. UV-sensitive superconducting nanowire single photon detectors for integration in an ion trap. OPTICS EXPRESS 2017; 25:8705-8720. [PMID: 28437948 DOI: 10.1364/oe.25.008705] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We demonstrate superconducting nanowire single photon detectors with 76 ± 4% system detection efficiency at a wavelength of 315 nm and an operating temperature of 3.2 K, with a background count rate below 1 count per second at saturated detection efficiency. We propose integrating these detectors into planar surface electrode radio-frequency Paul traps for use in trapped ion quantum information processing. We operate detectors integrated into test ion trap structures at 3.8 K both with and without typical radio-frequency trapping electric fields. The trapping fields reduce system detection efficiency by 9%, but do not increase background count rates.
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33
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Physicists propose football-pitch-sized quantum computer. Nature 2017; 542:151. [DOI: 10.1038/nature.2017.21423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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34
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De Motte D, Grounds AR, Rehák M, Rodriguez Blanco A, Lekitsch B, Giri GS, Neilinger P, Oelsner G, Il’ichev E, Grajcar M, Hensinger WK. Experimental system design for the integration of trapped-ion and superconducting qubit systems. QUANTUM INFORMATION PROCESSING 2016; 15:5385-5414. [PMID: 28408863 PMCID: PMC5367758 DOI: 10.1007/s11128-016-1368-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 06/11/2016] [Indexed: 06/07/2023]
Abstract
We present a design for the experimental integration of ion trapping and superconducting qubit systems as a step towards the realization of a quantum hybrid system. The scheme addresses two key difficulties in realizing such a system: a combined microfabricated ion trap and superconducting qubit architecture, and the experimental infrastructure to facilitate both technologies. Developing upon work by Kielpinski et al. (Phys Rev Lett 108(13):130504, 2012. doi:10.1103/PhysRevLett.108.130504), we describe the design, simulation and fabrication process for a microfabricated ion trap capable of coupling an ion to a superconducting microwave LC circuit with a coupling strength in the tens of kHz. We also describe existing difficulties in combining the experimental infrastructure of an ion trapping set-up into a dilution refrigerator with superconducting qubits and present solutions that can be immediately implemented using current technology.
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Affiliation(s)
- D. De Motte
- Department of Physics and Astronomy, University of Sussex, Brighton, BN1 9QH UK
| | - A. R. Grounds
- Department of Physics and Astronomy, University of Sussex, Brighton, BN1 9QH UK
| | - M. Rehák
- Department of Experimental Physics, Comenius University, 84248 Bratislava, Slovakia
| | - A. Rodriguez Blanco
- Department of Physics and Astronomy, University of Sussex, Brighton, BN1 9QH UK
| | - B. Lekitsch
- Department of Physics and Astronomy, University of Sussex, Brighton, BN1 9QH UK
| | - G. S. Giri
- Department of Physics and Astronomy, University of Sussex, Brighton, BN1 9QH UK
| | - P. Neilinger
- Department of Experimental Physics, Comenius University, 84248 Bratislava, Slovakia
| | - G. Oelsner
- Leibniz Institute of Photonic Technology, P.O. Box 100239, 07702 Jena, Germany
| | - E. Il’ichev
- Leibniz Institute of Photonic Technology, P.O. Box 100239, 07702 Jena, Germany
- Russian Quantum Center, 100 Novaya Street, Skolkovo, Moscow region 143025 Russia
| | - M. Grajcar
- Department of Experimental Physics, Comenius University, 84248 Bratislava, Slovakia
| | - W. K. Hensinger
- Department of Physics and Astronomy, University of Sussex, Brighton, BN1 9QH UK
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