1
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Cifuentes JD, Tanttu T, Gilbert W, Huang JY, Vahapoglu E, Leon RCC, Serrano S, Otter D, Dunmore D, Mai PY, Schlattner F, Feng M, Itoh K, Abrosimov N, Pohl HJ, Thewalt M, Laucht A, Yang CH, Escott CC, Lim WH, Hudson FE, Rahman R, Dzurak AS, Saraiva A. Bounds to electron spin qubit variability for scalable CMOS architectures. Nat Commun 2024; 15:4299. [PMID: 38769086 PMCID: PMC11106088 DOI: 10.1038/s41467-024-48557-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 05/06/2024] [Indexed: 05/22/2024] Open
Abstract
Spins of electrons in silicon MOS quantum dots combine exquisite quantum properties and scalable fabrication. In the age of quantum technology, however, the metrics that crowned Si/SiO2 as the microelectronics standard need to be reassessed with respect to their impact upon qubit performance. We chart spin qubit variability due to the unavoidable atomic-scale roughness of the Si/SiO2 interface, compiling experiments across 12 devices, and develop theoretical tools to analyse these results. Atomistic tight binding and path integral Monte Carlo methods are adapted to describe fluctuations in devices with millions of atoms by directly analysing their wavefunctions and electron paths instead of their energy spectra. We correlate the effect of roughness with the variability in qubit position, deformation, valley splitting, valley phase, spin-orbit coupling and exchange coupling. These variabilities are found to be bounded, and they lie within the tolerances for scalable architectures for quantum computing as long as robust control methods are incorporated.
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Affiliation(s)
- Jesús D Cifuentes
- School of Electrical Engineering and Telecommunications, University of New South Wales, NSW 2052, Sydney, NSW, Australia.
| | - Tuomo Tanttu
- School of Electrical Engineering and Telecommunications, University of New South Wales, NSW 2052, Sydney, NSW, Australia
- Diraq, Sydney, NSW, Australia
| | - Will Gilbert
- School of Electrical Engineering and Telecommunications, University of New South Wales, NSW 2052, Sydney, NSW, Australia
- Diraq, Sydney, NSW, Australia
| | - Jonathan Y Huang
- School of Electrical Engineering and Telecommunications, University of New South Wales, NSW 2052, Sydney, NSW, Australia
| | - Ensar Vahapoglu
- School of Electrical Engineering and Telecommunications, University of New South Wales, NSW 2052, Sydney, NSW, Australia
- Diraq, Sydney, NSW, Australia
| | - Ross C C Leon
- School of Electrical Engineering and Telecommunications, University of New South Wales, NSW 2052, Sydney, NSW, Australia
| | - Santiago Serrano
- School of Electrical Engineering and Telecommunications, University of New South Wales, NSW 2052, Sydney, NSW, Australia
| | - Dennis Otter
- School of Electrical Engineering and Telecommunications, University of New South Wales, NSW 2052, Sydney, NSW, Australia
| | - Daniel Dunmore
- School of Electrical Engineering and Telecommunications, University of New South Wales, NSW 2052, Sydney, NSW, Australia
| | - Philip Y Mai
- School of Electrical Engineering and Telecommunications, University of New South Wales, NSW 2052, Sydney, NSW, Australia
| | - Frédéric Schlattner
- School of Electrical Engineering and Telecommunications, University of New South Wales, NSW 2052, Sydney, NSW, Australia
- Solid State Physics Laboratory, Department of Physics, ETH Zurich, Zurich, 8093, Switzerland
| | - MengKe Feng
- School of Electrical Engineering and Telecommunications, University of New South Wales, NSW 2052, Sydney, NSW, Australia
| | - Kohei Itoh
- School of Fundamental Science and Technology, Keio University, Yokohama, Japan
| | | | | | - Michael Thewalt
- Department of Physics, Simon Fraser University, V5A 1S6, Burnaby, BC, Canada
| | - Arne Laucht
- School of Electrical Engineering and Telecommunications, University of New South Wales, NSW 2052, Sydney, NSW, Australia
- Diraq, Sydney, NSW, Australia
| | - Chih Hwan Yang
- School of Electrical Engineering and Telecommunications, University of New South Wales, NSW 2052, Sydney, NSW, Australia
- Diraq, Sydney, NSW, Australia
| | - Christopher C Escott
- School of Electrical Engineering and Telecommunications, University of New South Wales, NSW 2052, Sydney, NSW, Australia
- Diraq, Sydney, NSW, Australia
| | - Wee Han Lim
- School of Electrical Engineering and Telecommunications, University of New South Wales, NSW 2052, Sydney, NSW, Australia
- Diraq, Sydney, NSW, Australia
| | - Fay E Hudson
- School of Electrical Engineering and Telecommunications, University of New South Wales, NSW 2052, Sydney, NSW, Australia
- Diraq, Sydney, NSW, Australia
| | - Rajib Rahman
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Andrew S Dzurak
- School of Electrical Engineering and Telecommunications, University of New South Wales, NSW 2052, Sydney, NSW, Australia
- Diraq, Sydney, NSW, Australia
| | - Andre Saraiva
- School of Electrical Engineering and Telecommunications, University of New South Wales, NSW 2052, Sydney, NSW, Australia.
- Diraq, Sydney, NSW, Australia.
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2
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Gill TB, Pavlov S, Kidd CS, Dean P, Burnett AD, Dunn A, Li L, Abrosimov NV, Hübers HW, Linfield EH, Davies AG, Freeman JR. 2D Time-Domain Spectroscopy for Determination of Energy and Momentum Relaxation Rates of Hydrogen-Like Donor States in Germanium. ACS PHOTONICS 2024; 11:1447-1455. [PMID: 38645998 PMCID: PMC11027176 DOI: 10.1021/acsphotonics.3c01522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 03/12/2024] [Accepted: 03/13/2024] [Indexed: 04/23/2024]
Abstract
We present measurements of the coherence times of excited states of hydrogen-like arsenic impurities in germanium (Ge:As) using a table-top two-dimensional time-domain spectroscopy (2D-TDS) system. We show that this laboratory system is capable of resolving the coherence lifetimes of atomic-like excited levels of impurity centers in semiconductors, such as those used in solid-state quantum information technologies, on a subpicosecond time scale. By fitting the coherent nonlinear response of the system with the known intracenter transition frequencies, we are able to monitor coherent population transfer and decay of the transitions from the 2p0 and 2p± states for different low excitation pulse fields. Furthermore, by examining the off-diagonal resonances in the 2D frequency-domain map, we are able to identify coherences between excited electronic states that are not visible via conventional single-frequency pump-probe or Hahn-echo measurements.
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Affiliation(s)
- Thomas B. Gill
- School
of Electronic and Electrical Engineering, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K.
| | - Sergei Pavlov
- Institute
of Optical Sensor Systems, German Aerospace
Center (DLR), Berlin 12489, Germany
| | - Connor S. Kidd
- School
of Electronic and Electrical Engineering, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K.
| | - Paul Dean
- School
of Electronic and Electrical Engineering, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K.
| | - Andrew D. Burnett
- School
of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K.
| | - Aniela Dunn
- School
of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K.
| | - Lianhe Li
- School
of Electronic and Electrical Engineering, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K.
| | | | - Heinz-Wilhelm Hübers
- Institute
of Optical Sensor Systems, German Aerospace
Center (DLR), Berlin 12489, Germany
- Institut
für Physik, Humboldt-Universität
zu Berlin, Berlin 12489, Germany
| | - Edmund H. Linfield
- School
of Electronic and Electrical Engineering, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K.
| | - A. Giles Davies
- School
of Electronic and Electrical Engineering, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K.
| | - Joshua R. Freeman
- School
of Electronic and Electrical Engineering, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K.
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3
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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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4
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Wang Z, Feng M, Serrano S, Gilbert W, Leon RCC, Tanttu T, Mai P, Liang D, Huang JY, Su Y, Lim WH, Hudson FE, Escott CC, Morello A, Yang CH, Dzurak AS, Saraiva A, Laucht A. Jellybean Quantum Dots in Silicon for Qubit Coupling and On-Chip Quantum Chemistry. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2208557. [PMID: 36805699 DOI: 10.1002/adma.202208557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Revised: 01/13/2023] [Indexed: 05/12/2023]
Abstract
The small size and excellent integrability of silicon metal-oxide-semiconductor (SiMOS) quantum dot spin qubits make them an attractive system for mass-manufacturable, scaled-up quantum processors. Furthermore, classical control electronics can be integrated on-chip, in-between the qubits, if an architecture with sparse arrays of qubits is chosen. In such an architecture qubits are either transported across the chip via shuttling or coupled via mediating quantum systems over short-to-intermediate distances. This paper investigates the charge and spin characteristics of an elongated quantum dot-a so-called jellybean quantum dot-for the prospects of acting as a qubit-qubit coupler. Charge transport, charge sensing, and magneto-spectroscopy measurements are performed on a SiMOS quantum dot device at mK temperature and compared to Hartree-Fock multi-electron simulations. At low electron occupancies where disorder effects and strong electron-electron interaction dominate over the electrostatic confinement potential, the data reveals the formation of three coupled dots, akin to a tunable, artificial molecule. One dot is formed centrally under the gate and two are formed at the edges. At high electron occupancies, these dots merge into one large dot with well-defined spin states, verifying that jellybean dots have the potential to be used as qubit couplers in future quantum computing architectures.
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Affiliation(s)
- Zeheng Wang
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - MengKe Feng
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - Santiago Serrano
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - William Gilbert
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
- Diraq, Sydney, NSW, 2052, Australia
| | - Ross C C Leon
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - Tuomo Tanttu
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
- Diraq, Sydney, NSW, 2052, Australia
| | - Philip Mai
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - Dylan Liang
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - Jonathan Y Huang
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - Yue Su
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - Wee Han Lim
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
- Diraq, Sydney, NSW, 2052, Australia
| | - Fay E Hudson
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
- Diraq, Sydney, NSW, 2052, Australia
| | - Christopher C Escott
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
- Diraq, Sydney, NSW, 2052, Australia
| | - Andrea Morello
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - Chih Hwan Yang
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
- Diraq, Sydney, NSW, 2052, Australia
| | - Andrew S Dzurak
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
- Diraq, Sydney, NSW, 2052, Australia
| | - Andre Saraiva
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
- Diraq, Sydney, NSW, 2052, Australia
| | - Arne Laucht
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
- Diraq, Sydney, NSW, 2052, Australia
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5
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Schneider E, England J. Isotopically Enriched Layers for Quantum Computers Formed by 28Si Implantation and Layer Exchange. ACS APPLIED MATERIALS & INTERFACES 2023; 15:21609-21617. [PMID: 37075328 PMCID: PMC10165600 DOI: 10.1021/acsami.3c01112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
28Si enrichment is crucial for production of group IV semiconductor-based quantum computers. Cryogenically cooled, monocrystalline 28Si is a spin-free, vacuum-like environment where qubits are protected from sources of decoherence that cause loss of quantum information. Currently, 28Si enrichment techniques rely on deposition of centrifuged SiF4 gas, the source of which is not widely available, or bespoke ion implantation methods. Previously, conventional ion implantation into naturalSi substrates has produced heavily oxidized 28Si layers. Here we report on a novel enrichment process involving ion implantation of 28Si into Al films deposited on native-oxide free Si substrates followed by layer exchange crystallization. We measured continuous, oxygen-free epitaxial 28Si enriched to 99.7%. Increases in isotopic enrichment are possible, and improvements in crystal quality, aluminum content, and thickness uniformity are required before the process can be considered viable. TRIDYN models, used to model 30 keV 28Si implants into Al to understand the observed post-implant layers and to investigate the implanted layer exchange process window over different energy and vacuum conditions, showed that the implanted layer exchange process is insensitive to implantation energy and would increase in efficiency with oxygen concentrations in the implanter end-station by reducing sputtering. Required implant fluences are an order of magnitude lower than those required for enrichment by direct 28Si implants into Si and can be chosen to control the final thickness of the enriched layer. We show that implanted layer exchange could potentially produce quantum grade 28Si using conventional semiconductor foundry equipment within production-worthy time scales.
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Affiliation(s)
- Ella Schneider
- Surrey Ion Beam Centre, Advanced Technology Institute, University of Surrey, Guildford GU2 7XH, United Kingdom
| | - Jonathan England
- Surrey Ion Beam Centre, Advanced Technology Institute, University of Surrey, Guildford GU2 7XH, United Kingdom
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6
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Jin IK, Kumar K, Rendell MJ, Huang JY, Escott CC, Hudson FE, Lim WH, Dzurak AS, Hamilton AR, Liles SD. Combining n-MOS Charge Sensing with p-MOS Silicon Hole Double Quantum Dots in a CMOS platform. NANO LETTERS 2023; 23:1261-1266. [PMID: 36748989 DOI: 10.1021/acs.nanolett.2c04417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Holes in silicon quantum dots are receiving attention due to their potential as fast, tunable, and scalable qubits in semiconductor quantum circuits. Despite this, challenges remain in this material system including difficulties using charge sensing to determine the number of holes in a quantum dot, and in controlling the coupling between adjacent quantum dots. We address these problems by fabricating an ambipolar complementary metal-oxide-semiconductor (CMOS) device using multilayer palladium gates. The device consists of an electron charge sensor adjacent to a hole double quantum dot. We demonstrate control of the spin state via electric dipole spin resonance. We achieve smooth control of the interdot coupling rate over 1 order of magnitude and use the charge sensor to perform spin-to-charge conversion to measure the hole singlet-triplet relaxation time of 11 μs for a known hole occupation. These results provide a path toward improving the quality and controllability of hole spin-qubits.
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Affiliation(s)
- Ik Kyeong Jin
- School of Physics, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Krittika Kumar
- School of Physics, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Matthew J Rendell
- School of Physics, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Jonathan Yue Huang
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, New South Wales 2052, Australia
- Diraq, Sydney, New South Wales 2052, Australia
| | - Chris C Escott
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, New South Wales 2052, Australia
- Diraq, Sydney, New South Wales 2052, Australia
| | - Fay E Hudson
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, New South Wales 2052, Australia
- Diraq, Sydney, New South Wales 2052, Australia
| | - Wee Han Lim
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, New South Wales 2052, Australia
- Diraq, Sydney, New South Wales 2052, Australia
| | - Andrew S Dzurak
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, New South Wales 2052, Australia
- Diraq, Sydney, New South Wales 2052, Australia
| | - Alexander R Hamilton
- School of Physics, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Scott D Liles
- School of Physics, The University of New South Wales, Sydney, New South Wales 2052, Australia
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7
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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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8
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Huang JY, Lim WH, Leon RCC, Yang CH, Hudson FE, Escott CC, Saraiva A, Dzurak AS, Laucht A. A High-Sensitivity Charge Sensor for Silicon Qubits above 1 K. NANO LETTERS 2021; 21:6328-6335. [PMID: 33999635 DOI: 10.1021/acs.nanolett.1c01003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Recent studies of silicon spin qubits at temperatures above 1 K are encouraging demonstrations that the cooling requirements for solid-state quantum computing can be considerably relaxed. However, qubit readout mechanisms that rely on charge sensing with a single-island single-electron transistor (SISET) quickly lose sensitivity due to thermal broadening of the electron distribution in the reservoirs. Here we exploit the tunneling between two quantized states in a double-island single-electron transistor (SET) to demonstrate a charge sensor with an improvement in the signal-to-noise ratio by an order of magnitude compared to a standard SISET, and a single-shot charge readout fidelity above 99% up to 8 K at a bandwidth greater than 100 kHz. These improvements are consistent with our theoretical modeling of the temperature-dependent current transport for both types of SETs. With minor additional hardware overhead, these sensors can be integrated into existing qubit architectures for a high-fidelity charge readout at few-kelvin temperatures.
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Affiliation(s)
- Jonathan Yue Huang
- Centre for Quantum Computation & Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney 2052, Australia
| | - Wee Han Lim
- Centre for Quantum Computation & Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney 2052, Australia
| | - Ross C C Leon
- Centre for Quantum Computation & Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney 2052, Australia
| | - Chih Hwan Yang
- Centre for Quantum Computation & Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney 2052, Australia
| | - Fay E Hudson
- Centre for Quantum Computation & Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney 2052, Australia
| | - Christopher C Escott
- Centre for Quantum Computation & Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney 2052, Australia
| | - Andre Saraiva
- Centre for Quantum Computation & Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney 2052, Australia
| | - Andrew S Dzurak
- Centre for Quantum Computation & Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney 2052, Australia
| | - Arne Laucht
- Centre for Quantum Computation & Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney 2052, Australia
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9
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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] [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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10
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Stein RM, Barcikowski ZS, Pookpanratana SJ, Pomeroy JM, Stewart MD. Alternatives to aluminum gates for silicon quantum devices: defects and strain. JOURNAL OF APPLIED PHYSICS 2021; 130:10.1063/5.0036520. [PMID: 36733463 PMCID: PMC9890375 DOI: 10.1063/5.0036520] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 02/16/2021] [Indexed: 06/13/2023]
Abstract
Gate-defined quantum dots (QD) benefit from the use of small grain size metals for gate materials because it aids in shrinking the device dimensions. However, it is not clear what differences arise with respect to process-induced defect densities and inhomogeneous strain. Here, we present measurements of fixed charge, Q f , interface trap density, D it , the intrinsic film stress, σ, and the coefficient of thermal expansion, α as a function of forming gas anneal temperature for Al, Ti/Pd, and Ti/Pt gates. We show D it is minimal at an anneal temperature of 350 °C for all materials but Ti/Pd and Ti/Pt have higher Q f and D it compared to Al. In addition, σ and α increase with anneal temperature for all three metals with α larger than the bulk value. These results indicate that there is a tradeoff between minimizing defects and minimizing the impact of strain in quantum device fabrication.
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Affiliation(s)
- Ryan M. Stein
- Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
| | - Z. S. Barcikowski
- Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
| | - S. J. Pookpanratana
- National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - J. M. Pomeroy
- National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - M. D. Stewart
- National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
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11
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Hong Y, Ramanayaka AN, Stein R, Stewart MD, Pomeroy JM. Developing Single Layer MOS Quantum Dots for Diagnostic Qubits. JOURNAL OF VACUUM SCIENCE AND TECHNOLOGY. B, NANOTECHNOLOGY & MICROELECTRONICS : MATERIALS, PROCESSING, MEASUREMENT, & PHENOMENA : JVST B 2021; 39:10.1116/6.0000549. [PMID: 34249479 PMCID: PMC8269032 DOI: 10.1116/6.0000549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 12/08/2020] [Indexed: 06/13/2023]
Abstract
The design, fabrication and characterization of single metal gate layer, metal-oxide-semiconductor (MOS) quantum dot devices robust against dielectric breakdown are presented as prototypes for future diagnostic qubits. These devices were developed as a preliminary solution to a longer term goal of a qubit platform for intercomparison between materials or for in-line diagnostics, and to provide a testbed for establishing classical measurements predictive of coherence performance. For this stage, we seek a robust MOS design that is compatible with wafer and chip architectures, that has a reduced process overhead and is sufficiently capable of challenging and advancing our measurement capabilities. In this report, we present our initial batch of silicon MOS devices using a single gate layer, which have not exhibited any failures with gate voltage excursions > 10 V, but do exhibit the reduced electrostatic control expected of a single gate layer design. We observe quantum dot formation, capacitive charge sensing between channels, and reasonable effective electron temperatures that enable spin qubit studies. The costs and benefits of the trade-off between device performance and fabrication efficiency will be discussed, as well as opportunities for future improvements.
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12
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Abstract
Computational methods are the most effective tools we have besides scientific experiments to explore the properties of complex biological systems. Progress is slowing because digital silicon computers have reached their limits in terms of speed. Other types of computation using radically different architectures, including neuromorphic and quantum, promise breakthroughs in both speed and efficiency. Quantum computing exploits the coherence and superposition properties of quantum systems to explore many possible computational paths in parallel. This provides a fundamentally more efficient route to solving some types of computational problems, including several of relevance to biological simulations. In particular, optimization problems, both convex and non-convex, feature in many biological models, including protein folding and molecular dynamics. Early quantum computers will be small, reminiscent of the early days of digital silicon computing. Understanding how to exploit the first generation of quantum hardware is crucial for making progress in both biological simulation and the development of the next generations of quantum computers. This review outlines the current state-of-the-art and future prospects for quantum computing, and provides some indications of how and where to apply it to speed up bottlenecks in biological simulation.
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Affiliation(s)
- Viv Kendon
- Department of Physics; Joint Quantum Centre (JQC) Durham-Newcastle, Durham University, South Road, Durham DH1 3LE, UK
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13
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Takeda K, Noiri A, Yoneda J, Nakajima T, Tarucha S. Resonantly Driven Singlet-Triplet Spin Qubit in Silicon. PHYSICAL REVIEW LETTERS 2020; 124:117701. [PMID: 32242710 DOI: 10.1103/physrevlett.124.117701] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 12/12/2019] [Accepted: 02/20/2020] [Indexed: 06/11/2023]
Abstract
We report implementation of a resonantly driven singlet-triplet spin qubit in silicon. The qubit is defined by the two-electron antiparallel spin states and universal quantum control is provided through a resonant drive of the exchange interaction at the qubit frequency. The qubit exhibits long T_{2}^{*} exceeding 1 μs that is limited by dephasing due to the ^{29}Si nuclei rather than charge noise thanks to the symmetric operation and a large micromagnet Zeeman field gradient. The randomized benchmarking shows 99.6% single gate fidelity which is the highest reported for singlet-triplet qubits.
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Affiliation(s)
- K Takeda
- Center for Emergent Matter Science (CEMS), RIKEN, Wako-shi, Saitama 351-0198, Japan
| | - A Noiri
- Center for Emergent Matter Science (CEMS), RIKEN, Wako-shi, Saitama 351-0198, Japan
| | - J Yoneda
- Center for Emergent Matter Science (CEMS), RIKEN, Wako-shi, Saitama 351-0198, Japan
| | - T Nakajima
- Center for Emergent Matter Science (CEMS), RIKEN, Wako-shi, Saitama 351-0198, Japan
| | - S Tarucha
- Center for Emergent Matter Science (CEMS), RIKEN, Wako-shi, Saitama 351-0198, Japan
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14
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Schaal S, Ahmed I, Haigh JA, Hutin L, Bertrand B, Barraud S, Vinet M, Lee CM, Stelmashenko N, Robinson JWA, Qiu JY, Hacohen-Gourgy S, Siddiqi I, Gonzalez-Zalba MF, Morton JJL. Fast Gate-Based Readout of Silicon Quantum Dots Using Josephson Parametric Amplification. PHYSICAL REVIEW LETTERS 2020; 124:067701. [PMID: 32109120 DOI: 10.1103/physrevlett.124.067701] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 01/17/2020] [Indexed: 06/10/2023]
Abstract
Spins in silicon quantum devices are promising candidates for large-scale quantum computing. Gate-based sensing of spin qubits offers a compact and scalable readout with high fidelity, however, further improvements in sensitivity are required to meet the fidelity thresholds and measurement timescales needed for the implementation of fast feedback in error correction protocols. Here, we combine radio-frequency gate-based sensing at 622 MHz with a Josephson parametric amplifier, that operates in the 500-800 MHz band, to reduce the integration time required to read the state of a silicon double quantum dot formed in a nanowire transistor. Based on our achieved signal-to-noise ratio, we estimate that singlet-triplet single-shot readout with an average fidelity of 99.7% could be performed in 1 μs, well below the requirements for fault-tolerant readout and 30 times faster than without the Josephson parametric amplifier. Additionally, the Josephson parametric amplifier allows operation at a lower radio-frequency power while maintaining identical signal-to-noise ratio. We determine a noise temperature of 200 mK with a contribution from the Josephson parametric amplifier (25%), cryogenic amplifier (25%) and the resonator (50%), showing routes to further increase the readout speed.
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Affiliation(s)
- S Schaal
- London Centre for Nanotechnology, University College London, London WC1H 0AH, United Kingdom
| | - I Ahmed
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - J A Haigh
- Hitachi Cambridge Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - L Hutin
- CEA, LETI, Minatec Campus, F-38054 Grenoble, France
| | - B Bertrand
- CEA, LETI, Minatec Campus, F-38054 Grenoble, France
| | - S Barraud
- CEA, LETI, Minatec Campus, F-38054 Grenoble, France
| | - M Vinet
- CEA, LETI, Minatec Campus, F-38054 Grenoble, France
| | - C-M Lee
- Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - N Stelmashenko
- Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - J W A Robinson
- Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - J Y Qiu
- Quantum Nanoelectronics Laboratory, Department of Physics, University of California, Berkeley California 94720, USA
| | - S Hacohen-Gourgy
- Quantum Nanoelectronics Laboratory, Department of Physics, University of California, Berkeley California 94720, USA
| | - I Siddiqi
- Quantum Nanoelectronics Laboratory, Department of Physics, University of California, Berkeley California 94720, USA
| | - M F Gonzalez-Zalba
- Hitachi Cambridge Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - J J L Morton
- London Centre for Nanotechnology, University College London, London WC1H 0AH, United Kingdom
- Department of Electronic & Electrical Engineering, University College London, London WC1E 7JE, United Kingdom
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