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Noiri A, Takeda K, Nakajima T, Kobayashi T, Sammak A, Scappucci G, Tarucha S. A shuttling-based two-qubit logic gate for linking distant silicon quantum processors. Nat Commun 2022; 13:5740. [PMID: 36180449 PMCID: PMC9525571 DOI: 10.1038/s41467-022-33453-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 09/16/2022] [Indexed: 12/04/2022] Open
Abstract
Control of entanglement between qubits at distant quantum processors using a two-qubit gate is an essential function of a scalable, modular implementation of quantum computation. Among the many qubit platforms, spin qubits in silicon quantum dots are promising for large-scale integration along with their nanofabrication capability. However, linking distant silicon quantum processors is challenging as two-qubit gates in spin qubits typically utilize short-range exchange coupling, which is only effective between nearest-neighbor quantum dots. Here we demonstrate a two-qubit gate between spin qubits via coherent spin shuttling, a key technology for linking distant silicon quantum processors. Coherent shuttling of a spin qubit enables efficient switching of the exchange coupling with an on/off ratio exceeding 1000, while preserving the spin coherence by 99.6% for the single shuttling between neighboring dots. With this shuttling-mode exchange control, we demonstrate a two-qubit controlled-phase gate with a fidelity of 93%, assessed via randomized benchmarking. Combination of our technique and a phase coherent shuttling of a qubit across a large quantum dot array will provide feasible path toward a quantum link between distant silicon quantum processors, a key requirement for large-scale quantum computation. A coherent quantum link between distant quantum processors is desirable for scaling up of quantum computation. Noiri et al. demonstrate a strategy to link distant quantum processors in silicon, by implementing a shuttling-based two-qubit gate between spin qubits in a Si/SiGe triple quantum dot.
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Affiliation(s)
- Akito Noiri
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan.
| | - Kenta Takeda
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan
| | | | | | - Amir Sammak
- QuTech, Delft University of Technology, Delft, The Netherlands.,Netherlands Organization for Applied Scientific Research (TNO), Delft, The Netherlands
| | - Giordano Scappucci
- QuTech, Delft University of Technology, Delft, The Netherlands.,Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Seigo Tarucha
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan. .,RIKEN Center for Quantum Computing (RQC), Wako, Japan.
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2
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Nishiyama S, Kato K, Kobayashi M, Mizokuchi R, Mori T, Kodera T. The functions of a reservoir offset voltage applied to physically defined p-channel Si quantum dots. Sci Rep 2022; 12:10444. [PMID: 35729358 DOI: 10.1038/s41598-022-14669-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 06/10/2022] [Indexed: 11/08/2022] Open
Abstract
We propose and define a reservoir offset voltage as a voltage commonly applied to both reservoirs of a quantum dot and study the functions in p-channel Si quantum dots. By the reservoir offset voltage, the electrochemical potential of the quantum dot can be modulated. In addition, when quantum dots in different channels are capacitively coupled, the reservoir offset voltage of one of the QDs can work as a gate voltage for the others. Our results show that the technique will lead to reduction of the number of gate electrodes, which is advantageous for future qubit integration.
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3
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Noiri A, Takeda K, Nakajima T, Kobayashi T, Sammak A, Scappucci G, Tarucha S. Fast universal quantum gate above the fault-tolerance threshold in silicon. Nature 2022; 601:338-342. [PMID: 35046603 DOI: 10.1038/s41586-021-04182-y] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 10/26/2021] [Indexed: 11/09/2022]
Abstract
Fault-tolerant quantum computers that can solve hard problems rely on quantum error correction1. One of the most promising error correction codes is the surface code2, which requires universal gate fidelities exceeding an error correction threshold of 99 per cent3. Among the many qubit platforms, only superconducting circuits4, trapped ions5 and nitrogen-vacancy centres in diamond6 have delivered this requirement. Electron spin qubits in silicon7-15 are particularly promising for a large-scale quantum computer owing to their nanofabrication capability, but the two-qubit gate fidelity has been limited to 98 per cent owing to the slow operation16. Here we demonstrate a two-qubit gate fidelity of 99.5 per cent, along with single-qubit gate fidelities of 99.8 per cent, in silicon spin qubits by fast electrical control using a micromagnet-induced gradient field and a tunable two-qubit coupling. We identify the qubit rotation speed and coupling strength where we robustly achieve high-fidelity gates. We realize Deutsch-Jozsa and Grover search algorithms with high success rates using our universal gate set. Our results demonstrate universal gate fidelity beyond the fault-tolerance threshold and may enable scalable silicon quantum computers.
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Affiliation(s)
- Akito Noiri
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan.
| | - Kenta Takeda
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan
| | | | | | - Amir Sammak
- QuTech, Delft University of Technology, Delft, The Netherlands.,Netherlands Organisation for Applied Scientific Research (TNO), Delft, The Netherlands
| | - Giordano Scappucci
- QuTech, Delft University of Technology, Delft, The Netherlands.,Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Seigo Tarucha
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan. .,RIKEN Center for Quantum Computing (RQC), Wako, Japan.
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4
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Tadokoro M, Nakajima T, Kobayashi T, Takeda K, Noiri A, Tomari K, Yoneda J, Tarucha S, Kodera T. Designs for a two-dimensional Si quantum dot array with spin qubit addressability. Sci Rep 2021; 11:19406. [PMID: 34593827 PMCID: PMC8484262 DOI: 10.1038/s41598-021-98212-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Accepted: 09/03/2021] [Indexed: 11/16/2022] Open
Abstract
Electron spins in Si are an attractive platform for quantum computation, backed with their scalability and fast, high-fidelity quantum logic gates. Despite the importance of two-dimensional integration with efficient connectivity between qubits for medium- to large-scale quantum computation, however, a practical device design that guarantees qubit addressability is yet to be seen. Here, we propose a practical 3 × 3 quantum dot device design and a larger-scale design as a longer-term target. The design goal is to realize qubit connectivity to the four nearest neighbors while ensuring addressability. We show that a 3 × 3 quantum dot array can execute four-qubit Grover’s algorithm more efficiently than the one-dimensional counterpart. To scale up the two-dimensional array beyond 3 × 3, we propose a novel structure with ferromagnetic gate electrodes. Our results showcase the possibility of medium-sized quantum processors in Si with fast quantum logic gates and long coherence times.
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Affiliation(s)
- Masahiro Tadokoro
- Department of Electrical and Electronic Engineering, Tokyo Institute of Technology, Meguro-ku, Tokyo, 152-8552, Japan.,Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama, 351-0198, Japan
| | - Takashi Nakajima
- Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama, 351-0198, Japan
| | - Takashi Kobayashi
- RIKEN Center for Quantum Computing, RIKEN, Wako-shi, Saitama, 351-0198, Japan
| | - Kenta Takeda
- Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama, 351-0198, Japan
| | - Akito Noiri
- Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama, 351-0198, Japan
| | - Kaito Tomari
- Department of Electrical and Electronic Engineering, Tokyo Institute of Technology, Meguro-ku, Tokyo, 152-8552, Japan
| | - Jun Yoneda
- Tokyo Tech Academy for Super Smart Society, Tokyo Institute of Technology, Meguro-ku, Tokyo, 152-8552, Japan
| | - Seigo Tarucha
- Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama, 351-0198, Japan.,RIKEN Center for Quantum Computing, RIKEN, Wako-shi, Saitama, 351-0198, Japan
| | - Tetsuo Kodera
- Department of Electrical and Electronic Engineering, Tokyo Institute of Technology, Meguro-ku, Tokyo, 152-8552, Japan.
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5
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Kato K, Liu Y, Murakami S, Morita Y, Mori T. Electron beam lithography with negative tone resist for highly integrated silicon quantum bits. Nanotechnology 2021; 32:485301. [PMID: 34425562 DOI: 10.1088/1361-6528/ac201b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 08/23/2021] [Indexed: 06/13/2023]
Abstract
Process technologies have been developed for electron-beam (EB) lithography aimed at silicon quantum devices and their large-scale integration. It is necessary to understand the proximity effect and construct a method for its correction to perform EB lithography of fine and complicated structures. In this study, we investigate the lithography of Si quantum devices with a point-beam EB system and a maN 2401 negative tone resist, in order to correspond to various types of device structures. We optimize temperatures for specialized pre- and post-exposure bakes for forming ∼20 nm fine patterns with small line-edge roughness. Further, we demonstrated the fabrication of Si-on-insulator device patterns that have some tiny dots connected with many large wires/pads in the layout, with the careful tuning of the dose assignment. In this tuning, we used the EB process simulation to estimate the cumulative dose distribution effectively. In addition, we reproduced the experimentally obtained resist patterns via the EB process simulation after considering the mid-range effect, which is a factors in the proximity effect but is not yet deeply understood. The results of this study are expected to provide useful process technologies for EB lithography, which will help drastically accelerate the research on Si quantum devices with a high degree of freedom.
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Affiliation(s)
- Kimihiko Kato
- National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Yongxun Liu
- National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Shigenori Murakami
- National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Yukinori Morita
- National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Takahiro Mori
- National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Umezono, Tsukuba, Ibaraki 305-8568, Japan
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6
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Takeda K, Noiri A, Nakajima T, Yoneda J, Kobayashi T, Tarucha S. Quantum tomography of an entangled three-qubit state in silicon. Nat Nanotechnol 2021; 16:965-969. [PMID: 34099899 DOI: 10.1038/s41565-021-00925-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Accepted: 04/30/2021] [Indexed: 06/12/2023]
Abstract
Quantum entanglement is a fundamental property of coherent quantum states and an essential resource for quantum computing1. In large-scale quantum systems, the error accumulation requires concepts for quantum error correction. A first step toward error correction is the creation of genuinely multipartite entanglement, which has served as a performance benchmark for quantum computing platforms such as superconducting circuits2,3, trapped ions4 and nitrogen-vacancy centres in diamond5. Among the candidates for large-scale quantum computing devices, silicon-based spin qubits offer an outstanding nanofabrication capability for scaling-up. Recent studies demonstrated improved coherence times6-8, high-fidelity all-electrical control9-13, high-temperature operation14,15 and quantum entanglement of two spin qubits9,11,12. Here we generated a three-qubit Greenberger-Horne-Zeilinger state using a low-disorder, fully controllable array of three spin qubits in silicon. We performed quantum state tomography16 and obtained a state fidelity of 88.0%. The measurements witness a genuine Greenberger-Horne-Zeilinger class quantum entanglement that cannot be separated into any biseparable state. Our results showcase the potential of silicon-based spin qubit platforms for multiqubit quantum algorithms.
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Affiliation(s)
- Kenta Takeda
- Center for Emergent Matter Science (CEMS), RIKEN, Wako-shi, Saitama, Japan.
| | - Akito Noiri
- Center for Emergent Matter Science (CEMS), RIKEN, Wako-shi, Saitama, Japan
| | - Takashi Nakajima
- Center for Emergent Matter Science (CEMS), RIKEN, Wako-shi, Saitama, Japan
| | - Jun Yoneda
- Center for Emergent Matter Science (CEMS), RIKEN, Wako-shi, Saitama, Japan
- Tokyo Tech Academy for Super Smart Society, Tokyo Institute of Technology, Tokyo, Japan
| | - Takashi Kobayashi
- Center for Emergent Matter Science (CEMS), RIKEN, Wako-shi, Saitama, Japan
| | - Seigo Tarucha
- Center for Emergent Matter Science (CEMS), RIKEN, Wako-shi, Saitama, Japan.
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7
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Jirovec D, Hofmann A, Ballabio A, Mutter PM, Tavani G, Botifoll M, Crippa A, Kukucka J, Sagi O, Martins F, Saez-Mollejo J, Prieto I, Borovkov M, Arbiol J, Chrastina D, Isella G, Katsaros G. A singlet-triplet hole spin qubit in planar Ge. Nat Mater 2021; 20:1106-1112. [PMID: 34083775 DOI: 10.1038/s41563-021-01022-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 04/23/2021] [Indexed: 06/12/2023]
Abstract
Spin qubits are considered to be among the most promising candidates for building a quantum processor. Group IV hole spin qubits are particularly interesting owing to their ease of operation and compatibility with Si technology. In addition, Ge offers the option for monolithic superconductor-semiconductor integration. Here, we demonstrate a hole spin qubit operating at fields below 10 mT, the critical field of Al, by exploiting the large out-of-plane hole g-factors in planar Ge and by encoding the qubit into the singlet-triplet states of a double quantum dot. We observe electrically controlled g-factor difference-driven and exchange-driven rotations with tunable frequencies exceeding 100 MHz and dephasing times of 1 μs, which we extend beyond 150 μs using echo techniques. These results demonstrate that Ge hole singlet-triplet qubits are competing with state-of-the-art GaAs and Si singlet-triplet qubits. In addition, their rotation frequencies and coherence are comparable with those of Ge single spin qubits, but singlet-triplet qubits can be operated at much lower fields, emphasizing their potential for on-chip integration with superconducting technologies.
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Affiliation(s)
- Daniel Jirovec
- Institute of Science and Technology Austria, Klosterneuburg, Austria.
| | - Andrea Hofmann
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Andrea Ballabio
- Laboratory for Epitaxial Nanostructures on Silicon and Spintronics, Physics Department, Politecnico di Milano, Como, Italy
| | - Philipp M Mutter
- Department of Physics, University of Konstanz, Konstanz, Germany
| | - Giulio Tavani
- Laboratory for Epitaxial Nanostructures on Silicon and Spintronics, Physics Department, Politecnico di Milano, Como, Italy
| | - Marc Botifoll
- Catalan Institute of Nanoscience and Nanotechnology, Spanish National Research Council, Barcelona Institute of Science and Technology, Autonomous University of Barcelona, Barcelona, Spain
| | - Alessandro Crippa
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Josip Kukucka
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Oliver Sagi
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Frederico Martins
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | | | - Ivan Prieto
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Maksim Borovkov
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Jordi Arbiol
- Catalan Institute of Nanoscience and Nanotechnology, Spanish National Research Council, Barcelona Institute of Science and Technology, Autonomous University of Barcelona, Barcelona, Spain
- Catalan Institution for Research and Advanced Studies, Barcelona, Spain
| | - Daniel Chrastina
- Laboratory for Epitaxial Nanostructures on Silicon and Spintronics, Physics Department, Politecnico di Milano, Como, Italy
| | - Giovanni Isella
- Laboratory for Epitaxial Nanostructures on Silicon and Spintronics, Physics Department, Politecnico di Milano, Como, Italy
| | - Georgios Katsaros
- Institute of Science and Technology Austria, Klosterneuburg, Austria.
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8
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Yoneda J, Huang W, Feng M, Yang CH, Chan KW, Tanttu T, Gilbert W, Leon RCC, Hudson FE, Itoh KM, Morello A, Bartlett SD, Laucht A, Saraiva A, Dzurak AS. Coherent spin qubit transport in silicon. Nat Commun 2021; 12:4114. [PMID: 34226564 PMCID: PMC8257656 DOI: 10.1038/s41467-021-24371-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 05/23/2021] [Indexed: 11/09/2022] Open
Abstract
A fault-tolerant quantum processor may be configured using stationary qubits interacting only with their nearest neighbours, but at the cost of significant overheads in physical qubits per logical qubit. Such overheads could be reduced by coherently transporting qubits across the chip, allowing connectivity beyond immediate neighbours. Here we demonstrate high-fidelity coherent transport of an electron spin qubit between quantum dots in isotopically-enriched silicon. We observe qubit precession in the inter-site tunnelling regime and assess the impact of qubit transport using Ramsey interferometry and quantum state tomography techniques. We report a polarization transfer fidelity of 99.97% and an average coherent transfer fidelity of 99.4%. Our results provide key elements for high-fidelity, on-chip quantum information distribution, as long envisaged, reinforcing the scaling prospects of silicon-based spin qubits.
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Affiliation(s)
- J Yoneda
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia. .,Tokyo Tech Academy for Super Smart Society, Tokyo Institute of Technology, Tokyo, Japan.
| | - W Huang
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia.,Solid State Physics Laboratory, ETH Zurich, Zurich, Switzerland
| | - M Feng
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia
| | - C H Yang
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia
| | - K W Chan
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia
| | - T Tanttu
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia
| | - W Gilbert
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia
| | - R C C Leon
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia
| | - F E Hudson
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia
| | - K M Itoh
- School of Fundamental Science and Technology, Keio University, Yokohama, Japan
| | - A Morello
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia
| | - S D Bartlett
- Centre for Engineered Quantum Systems, School of Physics, University of Sydney, Sydney, NSW, Australia
| | - A Laucht
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia
| | - A Saraiva
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia
| | - A S Dzurak
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia.
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9
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de Leon NP, Itoh KM, Kim D, Mehta KK, Northup TE, Paik H, Palmer BS, Samarth N, Sangtawesin S, Steuerman DW. Materials challenges and opportunities for quantum computing hardware. Science 2021; 372:372/6539/eabb2823. [PMID: 33859004 DOI: 10.1126/science.abb2823] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Quantum computing hardware technologies have advanced during the past two decades, with the goal of building systems that can solve problems that are intractable on classical computers. The ability to realize large-scale systems depends on major advances in materials science, materials engineering, and new fabrication techniques. We identify key materials challenges that currently limit progress in five quantum computing hardware platforms, propose how to tackle these problems, and discuss some new areas for exploration. Addressing these materials challenges will require scientists and engineers to work together to create new, interdisciplinary approaches beyond the current boundaries of the quantum computing field.
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Affiliation(s)
- Nathalie P de Leon
- Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Kohei M Itoh
- School of Fundamental Science and Technology, Keio University, Yokohama 223-8522, Japan
| | - Dohun Kim
- Department of Physics and Astronomy and Institute of Applied Physics, Seoul National University, Seoul 08826, Korea
| | - Karan K Mehta
- Department of Physics, Institute for Quantum Electronics, ETH Zürich, 8092 Zürich, Switzerland
| | - Tracy E Northup
- Institut für Experimentalphysik, Universität Innsbruck, 6020 Innsbruck, Austria
| | - Hanhee Paik
- IBM Quantum, IBM T. J. Watson Research Center, Yorktown Heights, NY 10598, USA.
| | - B S Palmer
- Laboratory for Physical Sciences, University of Maryland, College Park, MD 20740, USA.,Quantum Materials Center, University of Maryland, College Park, MD 20742, USA
| | - N Samarth
- Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Sorawis Sangtawesin
- School of Physics and Center of Excellence in Advanced Functional Materials, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
| | - D W Steuerman
- Kavli Foundation, 5715 Mesmer Avenue, Los Angeles, CA 90230, USA
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10
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Kandel YP, Qiao H, Fallahi S, Gardner GC, Manfra MJ, Nichol JM. Adiabatic quantum state transfer in a semiconductor quantum-dot spin chain. Nat Commun 2021; 12:2156. [PMID: 33846333 PMCID: PMC8042124 DOI: 10.1038/s41467-021-22416-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 03/11/2021] [Indexed: 02/01/2023] Open
Abstract
Semiconductor quantum-dot spin qubits are a promising platform for quantum computation, because they are scalable and possess long coherence times. In order to realize this full potential, however, high-fidelity information transfer mechanisms are required for quantum error correction and efficient algorithms. Here, we present evidence of adiabatic quantum-state transfer in a chain of semiconductor quantum-dot electron spins. By adiabatically modifying exchange couplings, we transfer single- and two-spin states between distant electrons in less than 127 ns. We also show that this method can be cascaded for spin-state transfer in long spin chains. Based on simulations, we estimate that the probability to correctly transfer single-spin eigenstates and two-spin singlet states can exceed 0.95 for the experimental parameters studied here. In the future, state and process tomography will be required to verify the transfer of arbitrary single qubit states with a fidelity exceeding the classical bound. Adiabatic quantum-state transfer is robust to noise and pulse-timing errors. This method will be useful for initialization, state distribution, and readout in large spin-qubit arrays for gate-based quantum computing. It also opens up the possibility of universal adiabatic quantum computing in semiconductor quantum-dot spin qubits.
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Affiliation(s)
- Yadav P. Kandel
- grid.16416.340000 0004 1936 9174Department of Physics and Astronomy, University of Rochester, Rochester, NY USA
| | - Haifeng Qiao
- grid.16416.340000 0004 1936 9174Department of Physics and Astronomy, University of Rochester, Rochester, NY USA
| | - Saeed Fallahi
- grid.169077.e0000 0004 1937 2197Department of Physics and Astronomy, Purdue University, West Lafayette, IN USA ,grid.169077.e0000 0004 1937 2197Birck Nanotechnology Center, Purdue University, West Lafayette, IN USA
| | - Geoffrey C. Gardner
- grid.169077.e0000 0004 1937 2197Birck Nanotechnology Center, Purdue University, West Lafayette, IN USA ,grid.169077.e0000 0004 1937 2197School of Materials Engineering, Purdue University, West Lafayette, IN USA
| | - Michael J. Manfra
- grid.169077.e0000 0004 1937 2197Department of Physics and Astronomy, Purdue University, West Lafayette, IN USA ,grid.169077.e0000 0004 1937 2197Birck Nanotechnology Center, Purdue University, West Lafayette, IN USA ,grid.169077.e0000 0004 1937 2197School of Materials Engineering, Purdue University, West Lafayette, IN USA ,grid.169077.e0000 0004 1937 2197School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN USA
| | - John M. Nichol
- grid.16416.340000 0004 1936 9174Department of Physics and Astronomy, University of Rochester, Rochester, NY USA
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11
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Qiao H, Kandel YP, Dyke JSV, Fallahi S, Gardner GC, Manfra MJ, Barnes E, Nichol JM. Floquet-enhanced spin swaps. Nat Commun 2021; 12:2142. [PMID: 33837187 DOI: 10.1038/s41467-021-22415-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 03/02/2021] [Indexed: 02/01/2023] Open
Abstract
The transfer of information between quantum systems is essential for quantum communication and computation. In quantum computers, high connectivity between qubits can improve the efficiency of algorithms, assist in error correction, and enable high-fidelity readout. However, as with all quantum gates, operations to transfer information between qubits can suffer from errors associated with spurious interactions and disorder between qubits, among other things. Here, we harness interactions and disorder between qubits to improve a swap operation for spin eigenstates in semiconductor gate-defined quantum-dot spins. We use a system of four electron spins, which we configure as two exchange-coupled singlet-triplet qubits. Our approach, which relies on the physics underlying discrete time crystals, enhances the quality factor of spin-eigenstate swaps by up to an order of magnitude. Our results show how interactions and disorder in multi-qubit systems can stabilize non-trivial quantum operations and suggest potential uses for non-equilibrium quantum phenomena, like time crystals, in quantum information processing applications. Our results also confirm the long-predicted emergence of effective Ising interactions between exchange-coupled singlet-triplet qubits.
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12
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Abstract
Quantum information processing systems rely on a broad range of microwave technologies and have spurred development of microwave devices and methods in new operating regimes. Here we review the use of microwave signals and systems in quantum computing, with specific reference to three leading quantum computing platforms: trapped atomic ion qubits, spin qubits in semiconductors, and superconducting qubits. We highlight some key results and progress in quantum computing achieved through the use of microwave systems, and discuss how quantum computing applications have pushed the frontiers of microwave technology in some areas. We also describe open microwave engineering challenges for the construction of large-scale, fault-tolerant quantum computers.
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Affiliation(s)
- Joseph C Bardin
- Department of Electrical and Computer Engineering, University of Massachusetts Amherst, Amherst, MA 01003 USA
- Google LLC, Goleta, CA 93117 USA
| | - Daniel H Slichter
- Time and Frequency Division, National Institute of Standards and Technology, Boulder, CO 80305 USA
| | - David J Reilly
- Microsoft Inc., Microsoft Quantum Sydney, The University of Sydney, Sydney, NSW 2050, Australia
- ARC Centre of Excellence for Engineered Quantum Systems (EQuS), School of Physics, The University of Sydney, Sydney, NSW 2050, Australia
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Cerfontaine P, Botzem T, Ritzmann J, Humpohl SS, Ludwig A, Schuh D, Bougeard D, Wieck AD, Bluhm H. Closed-loop control of a GaAs-based singlet-triplet spin qubit with 99.5% gate fidelity and low leakage. Nat Commun 2020; 11:4144. [PMID: 32811818 PMCID: PMC7434764 DOI: 10.1038/s41467-020-17865-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 07/16/2020] [Indexed: 11/17/2022] Open
Abstract
Semiconductor spin qubits have recently seen major advances in coherence time and control fidelities, leading to a single-qubit performance that is on par with other leading qubit platforms. Most of this progress is based on microwave control of single spins in devices made of isotopically purified silicon. For controlling spins, the exchange interaction is an additional key ingredient which poses new challenges for high-fidelity control. Here, we demonstrate exchange-based single-qubit gates of two-electron spin qubits in GaAs double quantum dots. Using careful pulse optimization and closed-loop tuning, we achieve a randomized benchmarking fidelity of (99.50±0.04)% and a leakage rate of 0.13% out of the computational subspace. These results open new perspectives for microwave-free control of singlet-triplet qubits in GaAs and other materials. The exchange interaction between spins poses considerable challenges for high-fidelity control of semiconductor spin qubits. Here, the authors use pulse optimization and closed-loop control to achieve a gate fidelity of 99.5% for exchange-based single-qubit gates of two-electron spin qubits in GaAs.
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Affiliation(s)
- Pascal Cerfontaine
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, 52074, Aachen, Germany.
| | - Tim Botzem
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, 52074, Aachen, Germany
| | - Julian Ritzmann
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780, Bochum, Germany
| | - Simon Sebastian Humpohl
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, 52074, Aachen, Germany
| | - Arne Ludwig
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780, Bochum, Germany
| | - Dieter Schuh
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg, D-93040, Regensburg, Germany
| | - Dominique Bougeard
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg, D-93040, Regensburg, Germany
| | - Andreas D Wieck
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780, Bochum, Germany
| | - Hendrik Bluhm
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, 52074, Aachen, Germany.
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