Two-qubit silicon quantum processor with operation fidelity exceeding 99%

Mills, A. R.; Guinn, C. R.; Gullans, M. J.; Sigillito, A. J.; Feldman, M. M.; Petta, J. R.

doi:10.48550/arxiv.2111.11937

Cited by 18 publications

(23 citation statements)

References 31 publications

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“…Recent demonstrations of gate fidelities approaching the regime of fault-tolerance [7,8,17,18] confirm the potential of quantum computing in Si. Compared with other solid-state platforms, Si qubits offer the promise of extremely long coherence times and compatibility with large-scale semiconductor fabrication.…”

Section: Introductionmentioning

confidence: 96%

Coherent spin-valley oscillations in silicon

Cai¹,

Connors²,

Nichol³

2021

Preprint

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Electron spins in silicon quantum dots are excellent qubits because they have long coherence times, high gate fidelities, and are compatible with advanced semiconductor manufacturing techniques [1][2][3][4][5][6][7][8]. The valley degree of freedom, which results from the specific character of the Si band structure, is a unique feature of electrons in Si spin qubits [9, 10]. However, the small difference in energy between different valley levels often poses a challenge for quantum computing in Si [11, 12]. Here, we show that the spin-valley coupling in Si, which enables transitions between states with different spin and valley quantum numbers [13][14][15][16], enables coherent control of electron spins in Si. We demonstrate coherent manipulation of effective single-and two-electron spin states in a Si/SiGe double quantum dot without ac magnetic or electric fields. Our results illustrate that the valley degree of freedom, which is often regarded as an inconvenience, can itself enable quantum manipulation of electron spin states.

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Section: Introductionmentioning

confidence: 96%

Coherent spin-valley oscillations in silicon

Cai¹,

Connors²,

Nichol³

2021

Preprint

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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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“…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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Two-qubit silicon quantum processor with operation fidelity exceeding 99%

Cited by 18 publications

References 31 publications

Coherent spin-valley oscillations in silicon

Coherent spin-valley oscillations in silicon

A single hole spin with enhanced coherence in natural silicon

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

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