A coherent spin–photon interface in silicon

Mi, Xiao; Benito, Mónica; Putz, Stefan; Zajac, D. M.; Taylor, Jacob M.; Burkard, Guido; Petta, J. R.

doi:10.1038/nature25769

Cited by 423 publications

(475 citation statements)

References 64 publications

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“…However, scaling up to large quantum circuits in architecture based on QDs will require mastering of long-distance quantum communication between registers of a few qubits [9][10][11][12]. While applying multiple SWAP gates [13][14][15] to subsequent spin qubits in a chain of quantum dots is the most conceptually straightforward proposal, the two most recently successful avenues for achieving this goal are either coherently coupling stationary spin qubits to flying qubits, specifically to microwave photons [16][17][18], or simply making electron spin qubits mobile in a controlled way. The latter can be achieved in polar materials such as GaAs with surface acoustic waves [19][20][21] making a single electron travel for up to 100 µm [20] distance, or by gate voltage controlled transfer of an electron along a chain of quantum dots.…”

Section: Introductionmentioning

confidence: 99%

Adiabatic electron charge transfer between two quantum dots in presence of 1/f noise

Krzywda

Cywiński

2020

Phys. Rev. B

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Controlled adiabatic transfer of a single electron through a chain of quantum dots has been recently achieved in GaAs and Si/SiGe based quantum dots, opening prospects for turning stationary spin qubits into mobile ones, and solving in this way the problem of long-distance communication between quantum registers in a scalable quantum computing architecture based on quantum dots. We consider theoretically the process of such an electron transfer between two tunnel-coupled quantum dots, focusing on control by slowly varying the detuning of energy levels in the dots. We take into account the fluctuations in detuning caused by 1/f -type noise that is ubiquitous in semiconductor nanostructures, and analyze their influence on probability of successful transfer of an electron in a spin eigenstate. With numerical and analytical calculations we show that probability of electron not being transferred due to 1/f β noise in detuning is ∝ σ 2 t β−1 /v, where σ characterizes the noise amplitude, t is the interdot tunnel coupling, and v is the detuning sweep rate. Interestingly, this means that the noise-induced errors in charge transfer are independent of t for 1/f noise. For realistic parameters taken from experiments on silicon-based quantum dots, we obtain the minimal probability of charge transfer failure between a pair of dots is limited by 1/f noise in detuning to be the on order of 0.01. This means that in order to reliably transfer charges across many quantum dots, charge noise in the devices should be further suppressed, or tunnel couplings should be increased, in order to allow for faster transfer (and less exposure to noise), while not triggering the deterministic Landau-Zener excitation. arXiv:1909.11780v2 [cond-mat.mes-hall]

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Section: Introductionmentioning

confidence: 99%

Adiabatic electron charge transfer between two quantum dots in presence of 1/f noise

Krzywda

Cywiński

2020

Phys. Rev. B

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“…To determine the best possible performance of current technologies, we estimate the achievable SNR and measurement rate for parameters similar to those measured in Ref. 23. These are ω r = 2π × (5.8 GHz), κ = 2π × (1.8 MHz), b x = 2π × (420 MHz), and g c = 2π× (40 MHz).…”

Section: G Single-shot Readout Fidelity Estimatesmentioning

confidence: 99%

Optimal dispersive readout of a spin qubit with a microwave resonator

D’Anjou

Burkard

2019

Phys. Rev. B

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Strong coupling of semiconductor spin qubits to superconducting microwave resonators was recently demonstrated [X. Mi et al., Nature 555, 599 (2018); A. J. Landig et al., Nature 560, 179 (2018); N. Samkharadze et al., Science 359, 1123 T. Cubaynes et al., npj Quantum Inf. 5, 47 (2019)]. These breakthroughs pave the way for quantum information processing that combines the long coherence times of solid-state spin qubits with the long-distance connectivity, fast control, and fast high-fidelity quantum-non-demolition readout of existing superconducting qubit implementations. Here, we theoretically analyze and optimize the dispersive readout of a single spin in a semiconductor double quantum dot (DQD) coupled to a microwave resonator via its electric dipole moment. The strong spin-photon coupling arises from the motion of the electron spin in a local magnetic field gradient. We calculate the signal-to-noise ratio (SNR) of the readout accounting for both Purcell spin relaxation and spin relaxation arising from intrinsic electric noise within the semiconductor. We express the maximum achievable SNR in terms of the cooperativity associated with these two dissipation processes. We find that while the cooperativity increases with the strength of the dipole coupling between the DQD and the resonator, it does not depend on the strength of the magnetic field gradient. We then optimize the SNR as a function of experimentally tunable DQD parameters. We identify wide regions of parameter space where the unwanted backaction of the resonator photons on the qubit is small. Moreover, we find that the coupling of the resonator to other DQD transitions can enhance the SNR by at least a factor of two, a "straddling" effect [J. Koch et al., Phys. Rev. A 76, 042319 (2007)] that occurs only at nonzero energy detuning of the DQD double-well potential. We estimate that with current technology, single-shot readout fidelities in the range 82 − 95% can be achieved within a few µs of readout time without requiring the use of Purcell filters. arXiv:1905.09702v2 [cond-mat.mes-hall]

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“…In a weak spin-orbit material like silicon, a simple way to engineer such an interaction is to use magnetic field gradients [9,10,11], for instance from an on-chip micromagnet. This method has been used to demonstrate spin-photon strong coupling [12,13] and cavity-mediated spin-spin interactions [14] in silicon double-quantum-dots (DQDs). However, field gradients are undesirable for DFS TQDs since they induce qubit leakage [5].…”

Section: Introductionmentioning

confidence: 99%

Resonant exchange operation in triple-quantum-dot qubits for spin–photon transduction

Pan

Keating²,

Gyure³

et al. 2020

Quantum Sci. Technol.

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Triple quantum dots (TQDs) are promising semiconductor spin qubits because of their all-electrical control via fast, tunable exchange interactions and immunity to global magnetic fluctuations. These qubits couple to photons in the resonant exchange (RX) regime, when exchange is simultaneously active on both qubit axes. However, most theoretical work has been based on phenomenological Fermi-Hubbard models, which may not fully capture the complexity of the qubit spin-charge states in this regime. Here we investigate exchange in Si/SiGe and GaAs TQDs using full configuration interaction (FCI) calculations which better describe practical device operation. We show that high exchange operation in general, and the RX regime in particular, can differ significantly from simple models, presenting new challenges and opportunities for spin-photon coupling. We highlight the impact of device electrostatics and effective mass on exchange and identify a new operating point (XRX) where strong spin-photon coupling is most likely to occur in Si/SiGe TQDs. Based on our numerical results, we analyze the feasibility of a remote entanglement cavity iSWAP protocol and discuss design pathways for improving fidelity. Our analysis provides insight into the requirements for TQD spin-photon transduction and demonstrates more generally the necessity of accurate modeling of exchange in spin qubits. ‡ Present address:

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A coherent spin–photon interface in silicon

Cited by 423 publications

References 64 publications

Adiabatic electron charge transfer between two quantum dots in presence of 1/f noise

Adiabatic electron charge transfer between two quantum dots in presence of 1/f noise

Optimal dispersive readout of a spin qubit with a microwave resonator

Resonant exchange operation in triple-quantum-dot qubits for spin–photon transduction

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