Charge noise, spin-orbit coupling, and dephasing of single-spin qubits

Bermeister, Adam; Keith, D. A.; Culcer, Dimitrie

doi:10.1063/1.4901162

Cited by 56 publications

(42 citation statements)

References 78 publications

(99 reference statements)

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“…From this simple power-law spectrum, we obtain   1  2.01 and   1  , both of which agree well with the independent fitting results to the ACPMG envelopes and the T2 CPMG scaling described above. Such 1/f charge noise has commonly been observed in electrical properties in semiconductor devices [8][9][10] and is also measured as current fluctuations in our device ( Supplementary Fig. 1).…”

supporting

confidence: 70%

A quantum-dot spin qubit with coherence limited by charge noise and fidelity higher than 99.9%

Yoneda¹,

Takeda²,

Otsuka³

et al. 2017

Nature Nanotech

806

782

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The isolation of qubits from noise sources, such as surrounding nuclear spins and spin-electric susceptibility , has enabled extensions of quantum coherence times in recent pivotal advances towards the concrete implementation of spin-based quantum computation. In fact, the possibility of achieving enhanced quantum coherence has been substantially doubted for nanostructures due to the characteristic high degree of background charge fluctuations . Still, a sizeable spin-electric coupling will be needed in realistic multiple-qubit systems to address single-spin and spin-spin manipulations . Here, we realize a single-electron spin qubit with an isotopically enriched phase coherence time (20 μs) and fast electrical control speed (up to 30 MHz) mediated by extrinsic spin-electric coupling. Using rapid spin rotations, we reveal that the free-evolution dephasing is caused by charge noise-rather than conventional magnetic noise-as highlighted by a 1/f spectrum extended over seven decades of frequency. The qubit exhibits superior performance with single-qubit gate fidelities exceeding 99.9% on average, offering a promising route to large-scale spin-qubit systems with fault-tolerant controllability.

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supporting

confidence: 70%

A quantum-dot spin qubit with coherence limited by charge noise and fidelity higher than 99.9%

Yoneda¹,

Takeda²,

Otsuka³

et al. 2017

Nature Nanotech

806

782

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“…[2]), hints that the fluctuations of B dc in the superconducting magnet coils may not be the cause of 1/f 2.5 noise seen in the quantum dot and Si:P donor qubit systems at low frequency. At frequencies f = 2-20 kHz, our qubit noise follows the exponent of α = -0.8--1, resembling the nature of 1/f charge noise [6,[30][31][32][33]. The red (blue) dashed line is a plot of the function C 2 /ω (C 3 /ω 0.8 ), with C 2 = 3 × 10 7 (C 3 = 4 × 10 6 ).…”

mentioning

confidence: 74%

Assessment of a Silicon Quantum Dot Spin Qubit Environment via Noise Spectroscopy

et al. 2018

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Preserving coherence long enough to perform meaningful calculations is one of the major challenges on the pathway to large scale quantum computer implementations. Noise coupled in from the environment is the main contributing factor to decoherence but can be mitigated via engineering design and control solutions. However, this is only possible after acquiring a thorough understanding of the dominant noise sources and their spectrum. In this paper, we employ a silicon quantum dot spin qubit as a metrological device to study the noise environment experienced by the qubit. We compare the sensitivity of this qubit to electrical noise with that of an implanted silicon donor qubit in the same environment and measurement set-up. Our results show that, as expected, a quantum dot spin qubit is more sensitive to electrical noise than a donor spin qubit due to the larger Stark shift, and the noise spectroscopy data shows pronounced charge noise contributions at intermediate frequencies (2-20 kHz).

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“…The dephasing rate is given by (T * 2 ) −1 = (δω) 2 τ S /2, where δ ω is the qubit energy shift when the trap is charged, and τ S is the switching time [36]. Together with its image in the gate, a dipole e d is created, resulting in a dipole potential…”

Section: Dephasing From Electric Field Fluctuationsmentioning

confidence: 99%

“…We also find that dephasing from Johnsonlimited gate voltage noise, and from two-level (tunneling) systems (TLS), are ∼ 10 7 and ∼ 10 4 times weaker, respectively, compared with RTS. [36] There are only a few spin resonance experiments on acceptors [58,[76][77][78][79][80][81], none of which feature strain and an interface. [50] We expect hyperfine-induced decoherence in nat Si to be weak since it has only 4.7 % of spin-bearing isotopes and hyperfine interactions are weaker for holes than electrons.…”

mentioning

confidence: 99%

Charge-Insensitive Single-Atom Spin-Orbit Qubit in Silicon

et al. 2016

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High fidelity entanglement of an on-chip array of spin qubits poses many challenges. Spin-orbit coupling (SOC) can ease some of these challenges by enabling long-ranged entanglement via electric dipole-dipole interactions, microwave photons, or phonons. However, SOC exposes conventional spin qubits to decoherence from electrical noise. Here, we propose an acceptor-based spin-orbit qubit in silicon offering long-range entanglement at a sweet spot where the qubit is protected from electrical noise. The qubit relies on quadrupolar SOC with the interface and gate potentials. As required for surface codes, 10^{5} electrically mediated single-qubit and 10^{4} dipole-dipole mediated two-qubit gates are possible in the predicted spin lifetime. Moreover, circuit quantum electrodynamics with single spins is feasible, including dispersive readout, cavity-mediated entanglement, and spin-photon entanglement. An industrially relevant silicon-based platform is employed.

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Charge noise, spin-orbit coupling, and dephasing of single-spin qubits

Cited by 56 publications

References 78 publications

A quantum-dot spin qubit with coherence limited by charge noise and fidelity higher than 99.9%

A quantum-dot spin qubit with coherence limited by charge noise and fidelity higher than 99.9%

Assessment of a Silicon Quantum Dot Spin Qubit Environment via Noise Spectroscopy

Charge-Insensitive Single-Atom Spin-Orbit Qubit in Silicon

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