Decoherence in a superconducting quantum bit circuit

Ithier, G.; Collin, Eddy; Joyez, P.; Meeson, P. J.; Vion, Denis; Estève, D.; Chiarello, F.; Shnirman, Alexander; Makhlin, Yuriy; Schriefl, Josef; Schön, Gerd

doi:10.1103/physrevb.72.134519

Cited by 562 publications

(874 citation statements)

References 46 publications

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“…(10)(11), this can be derived by applying the Wiener-Khintchine theorem to the cross correlation function, which this time simply gives R (m) b ′ b ′′ = b 2 (the subscript b ′ b ′′ indicates two interleaved sub-series obtained from the original series b n ), and therefore…”

Section: Cross-psd: White-noise Eliminationmentioning

confidence: 99%

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Spectroscopy of low-frequency noise and its temperature dependence in a superconducting qubit

et al. 2012

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We report a direct measurement of the low-frequency noise spectrum in a superconducting flux qubit. Our method uses the noise sensitivity of a free-induction Ramsey interference experiment, comprising free evolution in the presence of noise for a fixed period of time followed by single-shot qubit-state measurement. Repeating this procedure enables Fourier-transform noise spectroscopy with access to frequencies up to the achievable repetition rate, a regime relevant to dephasing in ensemble-averaged time-domain measurements such as Ramsey interferometry. Rotating the qubit's quantization axis allows us to measure two types of noise: effective flux noise and effective criticalcurrent or charge noise. For both noise sources, we observe that the very same 1/f -type power laws measured at considerably higher frequencies (0.2 − 20 MHz) are consistent with the noise in the 0.01 − 100-Hz range measured here. We find no evidence of temperature dependence of the noises over 65 − 200 mK, and also no evidence of time-domain correlations between the two noises. These methods and results are pertinent to the dephasing of all superconducting qubits.

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Section: Cross-psd: White-noise Eliminationmentioning

confidence: 99%

“…Their noise is known to be due to local fluctuators [6][7][8][9] and the spectrum exhibits a 1/f α powerlaw dependence from hertz to tens of megahertz [10][11][12][13][14] . Its dependence on the device geometry 15,16 merits further study.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopy of low-frequency noise and its temperature dependence in a superconducting qubit

et al. 2012

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“…We should mention, however, that decoherence in some versions of charge qubits, namely quantronium and transmon, has been studied in greater detail [47][48][49]. We have measured the charge qubit energy relaxation in a wide range of the qubit parameters and found that it is caused by quantum noise with approximately linear frequency dependence.…”

Section: Energy Relaxationmentioning

confidence: 99%

Josephson charge qubits: a brief review

Pashkin

Astafiev

Yamamoto

et al. 2009

Quantum Inf Process

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The field of solid-state quantum computation is expanding rapidly initiated by our original charge qubit demonstrations. Various types of solid-state qubits are being studied, and their coherent properties are improving. The goal of this review is to summarize achievements on Josephson charge qubits. We cover the results obtained in our joint group of NEC Nano Electronics Research Laboratories and RIKEN Advanced Science Institute, also referring to the works done by other groups. Starting from a short introduction, we describe the principle of the Josephson charge qubit, its manipulation and readout. We proceed with coupling of two charge qubits and implementation of a logic gate. We also discuss decoherence issues. Finally, we show how a charge qubit can be used as an artificial atom coupled to a resonator to demonstrate lasing action.

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“…For this reason, environment-induced decoherence has been and is still a main obstacle to the practical application of superconducting qubits in quantum computation. [2,13,14,15,16] The environment-induced decoherence of superconducting qubits has been extensively studied both theoretically [15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33] and experimentally [2,8,13,21,25,34,35,36,37,38,39,40] in the absence of ac driving fields (free decay). Quite a few proposals, such as dynamical decoupling, [41,42,43,44,45,46,47,48] decoherence free subspaces, [49,50,51,52] spin echoes, …”

Section: Introductionmentioning

confidence: 99%

Relaxation and decoherence in a resonantly driven qubit

Zhou

Chu

Han

2008

J. Phys. B: At. Mol. Opt. Phys.

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Relaxation and decoherence of a qubit coupled to environment and driven by a resonant ac field are investigated by analytically solving Bloch equation of the qubit. It is found that the decoherence of a driven qubit can be decomposed into intrinsic and field-dependent ones. The intrinsic decoherence time equals to the decoherence time of the qubit in free decay while the fielddependent decoherence time is identical with the relaxation time of the qubit in driven oscillation. Analytical expressions of the relaxation and decoherence times are derived and applied to study a microwave-driven SQUID flux qubit. The results are in excellent agreement with those obtained by numerically solving the master equation. The relations between the relaxation and decoherence times of a qubit in free decay and driven oscillation can be used to extract the decoherence and thus dephasing times of the qubit by measuring its population evolution in free decay and resonantly driven oscillation.

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Decoherence in a superconducting quantum bit circuit

Cited by 562 publications

References 46 publications

Spectroscopy of low-frequency noise and its temperature dependence in a superconducting qubit

Spectroscopy of low-frequency noise and its temperature dependence in a superconducting qubit

Josephson charge qubits: a brief review

Relaxation and decoherence in a resonantly driven qubit

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