Evanescent-wave Johnson noise in small devices

Premakumar, Vickram N.; Vavilov, Maxim; Joynt, Robert

doi:10.1088/2058-9565/aa8e15

Cited by 9 publications

(15 citation statements)

References 49 publications

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“…4a) [29]. This effect is called evanescentwave Johnson noise (EWJN) [30][31][32] and is particularly strong near a metal interface. EWJN can cause spin relaxation at low temperatures because the evanescent waves constitute an electromagnetic reservoir that can absorb energy (Eq.…”

Section: B Evanescent-wave Johnson Noisementioning

confidence: 99%

Electron spin relaxation of single phosphorus donors in metal-oxide-semiconductor nanoscale devices

et al. 2019

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We analyze the electron spin relaxation rate 1/T1 of individual ion-implanted 31 P donors, in a large set of metal-oxide-semiconductor (MOS) silicon nanoscale devices, with the aim of identifying spin relaxation mechanisms peculiar to the environment of the spins. The measurements are conducted at low temperatures (T ≈ 100 mK), as a function of external magnetic field B0 and donor electrochemical potential µ D . We observe a magnetic field dependence of the form 1/T1 ∝ B 5 0 for B0 3 T, corresponding to the phonon-induced relaxation typical of donors in the bulk. However, the relaxation rate varies by up to two orders of magnitude between different devices. We attribute these differences to variations in lattice strain at the location of the donor. For B0 3 T, the relaxation rate changes to 1/T1 ∝ B0 for two devices. This is consistent with relaxation induced by evanescent-wave Johnson noise created by the metal structures fabricated above the donors. At such low fields, where T1 > 1 s, we also observe and quantify the spurious increase of 1/T1 when the electrochemical potential of the spin excited state |↑ comes in proximity to empty states in the charge reservoir, leading to spin-dependent tunneling that resets the spin to |↓ . These results give precious insights into the microscopic phenomena that affect spin relaxation in MOS nanoscale devices, and provide strategies for engineering spin qubits with improved spin lifetimes. arXiv:1812.06644v2 [cond-mat.mes-hall]

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Section: B Evanescent-wave Johnson Noisementioning

confidence: 99%

Electron spin relaxation of single phosphorus donors in metal-oxide-semiconductor nanoscale devices

et al. 2019

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“…Systematic studies of the effect of magnetic EWJN from a silver film on NV-center qubits have been performed 7,8 . In experiments on spin qubits in Si/SiGe platforms EWJN may in many cases be responsible for the spin relaxation [9][10][11] .…”

Section: Introductionmentioning

confidence: 99%

Magnetic noise from metal objects near qubit arrays

2021

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All metal objects support fluctuating currents that are responsible for evanescent-wave Johnson noise in their vicinity due both to thermal and quantum effects. The noise fields can decohere qubits in their neighborhood. It is quantified by the average value of B(x, t) B(x , t ) and its time Fourier transform. We develop the formalism particularly for objects whose dimensions are small compared with the skin depth, which is the appropriate regime for nanoscale devices. This leads to a general and surprisingly simple formula for the noise correlation function of an object of arbitrary shape. This formula has a clear physical interpretation in terms of induced currents in the object. It can also be the basis for straightforward numerical evaluation. For a sphere, a solution is given in closed form in terms of a generalized multipole expansion. Plots of the solution illustrate the physical principles involved. We give examples of how the spatial pattern of noise can affect quantum information processing in nearby qubits. The theory implies that if the qubit system is miniaturized to a scale D, then decoherence rates of qubits scale as 1/D.

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“…The main obstacle, as in many quantum computing implementations, is the presence of noise that causes decoherence. The sources of decoherence are many: noise from nuclear spin bath [7,8] evanescent-wave Johnson noise [9,10], random telegraph and 1/f -type charge noise [2,[11][12][13], and noise from phonons [14][15][16] are considered to be the main candidates.…”

Section: Introductionmentioning

confidence: 99%

Anisotropy with respect to the applied magnetic field of spin qubit decoherence times

Choi,

Joynt

2021

Preprint

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Electron spin qubits are a promising platform for quantum computation. Environmental noise impedes coherent operations by limiting the qubit relaxation (T1) and dephasing (T φ ) times. There are multiple sources of such noise, which makes it important to devise experimental techniques that can detect the spatial locations of these sources and determine which is the most important. In this paper, we propose that anisotropy in T1 and T φ with respect to the direction of the applied magnetic field can reveal much about these aspects of the noises. We investigate the anisotropy patterns of charge noise, evanescent-wave Johnson noise, and hyperfine noise. It is necessary to have a rather well-characterized sample to get the maximum benefit from this technique. The general anisotropy patterns are elucidated and then we calculate the expected anisotropy in a particular Si/SiGe quantum dot device.

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Evanescent-wave Johnson noise in small devices

Cited by 9 publications

References 49 publications

Electron spin relaxation of single phosphorus donors in metal-oxide-semiconductor nanoscale devices

Electron spin relaxation of single phosphorus donors in metal-oxide-semiconductor nanoscale devices

Magnetic noise from metal objects near qubit arrays

Anisotropy with respect to the applied magnetic field of spin qubit decoherence times

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