Microscopic models for charge-noise-induced dephasing of solid-state qubits

Beaudoin, Félix; Coish, W. A.

doi:10.1103/physrevb.91.165432

Cited by 36 publications

(31 citation statements)

References 85 publications

(152 reference statements)

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“…A commonly accepted microscopic model of 1/f β charge noise in solid state nanostructures assumes that then noise is caused by multiple fluctuating dipoles, each of them treated as a two-level fluctuator (TLF): a system randomly switching with rate γ between two states, each having a different dipole moment [43,58]. A microscopic nature of these TLFs in semiconductor devices hosting quantum dot spin qubits is not settled [59], but it is widely assumed that each such a TLF is a source of random telegraph noise (RTN), a non-Gaussian stochastic process characterized by correlation time τ c and a Lorentzian power spectral density…”

Section: A Model Of 1/f Charge Noisementioning

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: A Model Of 1/f Charge Noisementioning

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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“…Noise which is induced into the qubit system through the gate electrodes necessary for confining and controlling the electrons is typically Nyquist-Johnson noise [300,301,302,303] due to the finite temperature and shot-noise [304] due to quantization (graininess) of electric charge. Like magnetic noise, charge noise also depends on the system [112,305,293], however, to a smaller degree than for magnetic noise from nuclear spins, e.g., charge noise can be enhanced in the presence of piezoelectric phonons and their coupling strength. Therefore, charge noise cannot be changed significantly if the host material is replaced, since freely-moving electrons exist in every semiconductor and every device is connected to wires.…”

Section: Charge Noisementioning

confidence: 99%

Three-electron spin qubits

Russ

Burkard

2017

J. Phys.: Condens. Matter

104

117

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The goal of this article is to review the progress of three-electron spin qubits from their inception to the state of the art. We direct the main focus towards the exchange-only qubit (Bacon et al 2000 Phys. Rev. Lett. 85 1758-61, DiVincenzo et al 2000 Nature 408 339) and its derived versions, e.g. the resonant exchange (RX) qubit, but we also discuss other qubit implementations using three electron spins. For each three-spin qubit we describe the qubit model, the envisioned physical realization, the implementations of single-qubit operations, as well as the read-out and initialization schemes. Two-qubit gates and decoherence properties are discussed for the RX qubit and the exchange-only qubit, thereby completing the list of requirements for quantum computation for a viable candidate qubit implementation. We start by describing the full system of three electrons in a triple quantum dot, then discuss the charge-stability diagram, restricting ourselves to the relevant subsystem, introduce the qubit states, and discuss important transitions to other charge states (Russ et al 2016 Phys. Rev. B 94 165411). Introducing the various qubit implementations, we begin with the exchange-only qubit (DiVincenzo et al 2000 Nature 408 339, Laird et al 2010 Phys. Rev. B 82 075403), followed by the RX qubit (Medford et al 2013 Phys. Rev. Lett. 111 050501, Taylor et al 2013 Phys. Rev. Lett. 111 050502), the spin-charge qubit (Kyriakidis and Burkard 2007 Phys. Rev. B 75 115324), and the hybrid qubit (Shi et al 2012 Phys. Rev. Lett. 108 140503, Koh et al 2012 Phys. Rev. Lett. 109 250503, Cao et al 2016 Phys. Rev. Lett. 116 086801, Thorgrimsson et al 2016 arXiv:1611.04945). The main focus will be on the exchange-only qubit and its modification, the RX qubit, whose single-qubit operations are realized by driving the qubit at its resonant frequency in the microwave range similar to electron spin resonance. Two different types of two-qubit operations are presented for the exchange-only qubits which can be divided into short-ranged and long-ranged interactions. Both of these interaction types are expected to be necessary in a large-scale quantum computer. The short-ranged interactions use the exchange coupling by placing qubits next to each other and applying exchange-pulses (DiVincenzo et al 2000 Nature 408 339, Fong and Wandzura 2011 Quantum Inf. Comput. 11 1003, Setiawan et al 2014 Phys. Rev. B 89 085314, Zeuch et al 2014 Phys. Rev. B 90 045306, Doherty and Wardrop 2013 Phys. Rev. Lett. 111 050503, Shim and Tahan 2016 Phys. Rev. B 93 121410), while the long-ranged interactions use the photons of a superconducting microwave cavity as a mediator in order to couple two qubits over long distances (Russ and Burkard 2015 Phys. Rev. B 92 205412, Srinivasa et al 2016 Phys. Rev. B 94 205421). The nature of the three-electron qubit states each having the same total spin and total spin in z-direction (same Zeeman energy) provides a natural protection against several sources of noise (DiVincenzo et al 2000 Nature 408 339, Taylor et al 2013 Phys. R...

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“…Since the qubit is in the lowest valley eigenstate, valley relaxation will only be important around hotspots. Yet the intervalley spin-orbit coupling could enhance decoherence mechanisms already active in the absence of valley-orbit coupling 15,[41][42][43][44][45][46][47][48] . Moreover, interface roughness is unavoidable in heterostructures, giving rise to fluctuations in the z-position of the interface that couple different valley eigenstates 18 .…”

Section: Decoherencementioning

confidence: 99%

Electrically driven spin qubit based on valley mixing

et al. 2017

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The electrical control of single spin qubits based on semiconductor quantum dots is of great interest for scalable quantum computing since electric fields provide an alternative mechanism for qubit control compared with magnetic fields and can also be easier to produce. Here we outline the mechanism for a drastic enhancement in the electrically-driven spin rotation frequency for silicon quantum dot qubits in the presence of a step at a heterointerface. The enhancement is due to the strong coupling between the ground and excited states which occurs when the electron wave function overcomes the potential barrier induced by the interface step. We theoretically calculate single qubit gate times tπ of 170 ns for a quantum dot confined at a silicon/silicon-dioxide interface. The engineering of such steps could be used to achieve fast electrical rotation and entanglement of spin qubits despite the weak spin-orbit coupling in silicon.

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Microscopic models for charge-noise-induced dephasing of solid-state qubits

Cited by 36 publications

References 85 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

Three-electron spin qubits

Electrically driven spin qubit based on valley mixing

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