Decoherence in qubits due to low-frequency noise

Bergli, Joakim; Galperin, Y. M.; Altshuler, B. L.

doi:10.1088/1367-2630/11/2/025002

Cited by 139 publications

(187 citation statements)

References 77 publications

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“…The signal decay is calculated by dividing the probability distribution to partial probabilities, p(φ, t) = p + (φ, t) + p − (φ, t), to accumulate phase φ while the TLF is in the up or down state: 33,45 χ(t) = dφp(φ, t)e iφ .…”

Section: A Single Fluctuatormentioning

confidence: 99%

Non-Gaussian signatures and collective effects in charge noise affecting a dynamically decoupled qubit

Ramon

2015

Phys. Rev. B

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The effects of a collection of classical two-level charge fluctuators on the coherence of a dynamicallydecoupled qubit are studied. Distinct dynamics are found at different qubit working positions. Exact analytical formulae are derived at pure dephasing and approximate solutions are found at the general working position, for weakly-and strongly-coupled fluctuators. Analysis of these solutions, combined with numerical simulations of the multiple random telegraph processes, reveal the scaling of the noise with the number of fluctuators and the number of control pulses, as well as dependence on other parameters of the qubit-fluctuators system. These results can be used to determine potential microscopic models for the charge environment by performing noise spectroscopy.

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Section: A Single Fluctuatormentioning

confidence: 99%

Non-Gaussian signatures and collective effects in charge noise affecting a dynamically decoupled qubit

Ramon

2015

Phys. Rev. B

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“…It is therefore of considerate importance for applications to mitigate this noise effectively. 1/f noise can be understood as arising from the collective effect of multiple sources of telegraph noise that are coupled to the quantum system of interest, with the weight of each source scaling as the inverse characteristic decay-rate of that source [16,20].…”

Section: Examplesmentioning

confidence: 99%

Control of noisy quantum systems: Field-theory approach to error mitigation

Hipolito

Goldbart

2016

Phys. Rev. A

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We consider the basic quantum-control task of obtaining a target unitary operation (i.e., a quantum gate) via control fields that couple to the quantum system and are chosen to best mitigate errors resulting from time-dependent noise, which frustrate this task. We allow for two sources of noise: fluctuations in the control fields and fluctuations arising from the environment. We address the issue of control-error mitigation by means of a formulation rooted in the Martin-Siggia-Rose (MSR) approach to noisy, classical statistical-mechanical systems. To do this, we express the noisy control problem in terms of a path integral, and integrate out the noise to arrive at an effective, noise-free description. We characterize the degree of success in error mitigation via a fidelity metric, which characterizes the proximity of the sought-after evolution to ones that are achievable in the presence of noise. Error mitigation is then best accomplished by applying the optimal control fields, i.e., those that maximize the fidelity subject to any constraints obeyed by the control fields. To make connection with MSR, we reformulate the fidelity in terms of a Schwinger-Keldysh (SK) path integral, with the added twist that the "forward" and "backward" branches of the time-contour are inequivalent with respect to the noise. The present approach naturally and readily allows the incorporation of constraints on the control fields-a useful feature in practice, given that constraints feature in all real experiments. We illustrate this MSR-SK reformulation by considering a model system consisting of a single spin-s freedom (with s arbitrary), focusing on the case of 1/f noise in the weak-noise limit. We discover that optimal error-mitigation is accomplished via a universal control field protocol that is valid for all s, from the qubit (i.e., s = 1/2) case to the classical (i.e., s → ∞) limit. In principle, this MSR-SK approach provides a transparent framework for addressing quantum control in the presence of noise for systems of arbitrary complexity.

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“…The diagonal matrix elements of noise, λ nn , are responsible for decoherence, and the offdiagonal matrix elements, λ mn (m = n), lead to the relaxation processes. In what follows, we use a spinfluctuator model of noise, modeling the noise by an ensemble of fluctuators [34][35][36]. The evolution of the average diagonal components of the density matrix is described by the following system of integro-differential equations (see Appendix B):…”

Section: Noise-assisted Electron Transfer To the Sinkmentioning

confidence: 99%

Noise-assisted quantum electron transfer in photosynthetic complexes

et al. 2013

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Electron transfer (ET) between primary electron donors and acceptors is modeled in the photosystem II reaction center (RC). Our model includes (i) two discrete energy levels associated with donor and acceptor, interacting through a dipole-type matrix element and (ii) two continuum manifolds of electron energy levels ("sinks"), which interact directly with the donor and acceptor. Namely, two discrete energy levels of the donor and acceptor are embedded in their independent sinks through the corresponding interaction matrix elements. We also introduce classical (external) noise which acts simultaneously on the donor and acceptor (collective interaction). We derive a closed system of integro-differential equations which describes the non-Markovian quantum dynamics of the ET. A region of parameters is found in which the ET dynamics can be simplified, and described by coupled ordinary differential equations. Using these simplified equations, both sharp and flat redox potentials are analyzed. We analytically and numerically obtain the characteristic parameters that optimize the ET rates and efficiency in this system.

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Decoherence in qubits due to low-frequency noise

Cited by 139 publications

References 77 publications

Non-Gaussian signatures and collective effects in charge noise affecting a dynamically decoupled qubit

Non-Gaussian signatures and collective effects in charge noise affecting a dynamically decoupled qubit

Control of noisy quantum systems: Field-theory approach to error mitigation

Noise-assisted quantum electron transfer in photosynthetic complexes

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