Fast universal quantum gate above the fault-tolerance threshold in silicon

Noiri, Akito; Takeda, Kenta; Nakajima, Takashi; Kobayashi, Takashi; Sammak, Amir; Scappucci, Giordano; Tarucha, Seigo

doi:10.1038/s41586-021-04182-y

Cited by 297 publications

(190 citation statements)

References 44 publications

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“…In the global effort to build scalable quantum processors, spin qubits in semiconductor quantum dots 1 are progressively making their mark 2 . We highlight, in particular, the achievement of single- 3,4 and two-qubit [5][6][7][8] gate fidelities well above 99%, the first realizations of multi-qubit arrays 9,10 , and a demonstrated compatibility with industrial-grade semiconductor manufacturing technologies [11][12][13] .…”

Section: Introductionmentioning

confidence: 95%

A single hole spin with enhanced coherence in natural silicon

Piot¹,

B.²,

Schmitt³

et al. 2022

Preprint

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Semiconductor spin qubits based on spin-orbit states are responsive to electric field excitation allowing for practical, fast and potentially scalable qubit control. Spinelectric susceptibility, however, renders these qubits generally vulnerable to electrical noise, which limits their coherence time. Here we report on a spin-orbit qubit consisting of a single hole electrostatically confined in a natural silicon metal-oxidesemiconductor device. By varying the magnetic field orientation, we reveal the existence of operation sweet spots where the impact of charge noise is minimized while preserving an efficient electric-dipole spin control. We correspondingly observe an extension of the Hahn-echo coherence time up to 88 µs, exceeding by an order of magnitude the best reported values for hole-spin qubits, and approaching the state-of-the-art for electron spin qubits with synthetic spin-orbit coupling in isotopically-purified silicon. This finding largely enhances the prospects of silicon-based hole spin qubits for scalable quantum information processing.

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Section: Introductionmentioning

confidence: 95%

A single hole spin with enhanced coherence in natural silicon

Piot¹,

B.²,

Schmitt³

et al. 2022

Preprint

View full text Add to dashboard Cite

show abstract

“…Electrostatically defined quantum dots are promising candidates for scalable quantum computation and simulation [1][2][3]. They can achieve universal quantum computation [4] with gates reaching high fidelity [5,6]. Their properties are attractive for large scale quantum processors, namely all-electrical control, compact size [2], and potential operating temperatures of above 1K [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Identifying Pauli spin blockade using deep learning

Schuff¹,

Lennon²,

Geyer³

et al. 2022

Preprint

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Pauli spin blockade (PSB) can be employed as a great resource for spin qubit initialisation and readout even at elevated temperatures but it can be difficult to identify. We present a machine learning algorithm capable of automatically identifying PSB using charge transport measurements. The scarcity of PSB data is circumvented by training the algorithm with simulated data and by using cross-device validation. We demonstrate our approach on a silicon field-effect transistor device and report an accuracy of 96% on different test devices, giving evidence that the approach is robust to device variability. The approach is expected to be employable across all types of quantum dot devices.

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“…Silicon heterostructures have emerged as a very promising material platform for spin-based quantum information processing [1,2]. Recently two-qubit gates in silicon spin qubits were demonstrated with an overall fidelity exceeding 99% by a number of experimental studies [3][4][5][6], a very important step towards realizing faulttolerant silicon-based quantum computation. The intrinsic spin-orbit coupling (SOC) in silicon quantum dots is very weak and (largely) originates from the interface inversion asymmetry [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Theory of Silicon Spin Qubit Relaxation in a Synthetic Spin-Orbit Field

Hosseinkhani¹,

Burkard²

2022

Preprint

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We develop the theory of single-electron silicon spin qubit relaxation in the presence of a magnetic field gradient. Such field gradients are routinely generated by on-chip micromagnets to allow for electrically controlled quantum gates on spin qubits. We build on a valley-dependent envelope function theory that enables the analysis of the electron wave function in a silicon quantum dot with an arbitrary roughness at the interface. We assume the presence of single-layer atomic steps at a Si/SiGe interface, and study how the presence of a gradient field modifies the spin-mixing mechanisms. We show that our theoretical modeling can quantitatively reproduce results of experimental measurements of qubit relaxation in silicon in the presence of a micromagnet. We further study in detail how a field gradient can modify the EDSR Rabi frequency of a silicon spin qubit. While this strongly depends on the details of the interface roughness, interestingly, we find that adding a micromagnet on top of a spin qubit with an ideal interface can even reduce the EDSR frequency within some interval of the external magnetic field strength.

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Fast universal quantum gate above the fault-tolerance threshold in silicon

Abstract: Important note To cite this publication, please use the final published version (if applicable).Please check the document version above.

Cited by 297 publications

References 44 publications

A single hole spin with enhanced coherence in natural silicon

A single hole spin with enhanced coherence in natural silicon

Identifying Pauli spin blockade using deep learning

Theory of Silicon Spin Qubit Relaxation in a Synthetic Spin-Orbit Field

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