Decoherence from ensembles of two-level fluctuators

1/f noise, the major source of dephasing in Josephson qubits, may be produced by an ensemble of two-level systems. Depending on the statistical properties of their distribution, the noise distribution can be Gaussian or non-Gaussian. The latter situation is realized, for instance, when the distribution of coupling strengths has a slowly decaying power-law tail. In this regime, questions of self-averaging and sample-to-sample fluctuations become crucial. We study the dephasing process for a class of distribution functions and analyse the self-averaging properties of the results.

[1]  Yuriy Makhlin,et al.  Dephasing of solid-state qubits at optimal points. , 2003, Physical review letters.

[2]  A. Cottet,et al.  Implémentation d'un bit quantique dans un circuit supraconducteur / Implementation of a quantum bit in a superconducting circuit , 2002 .

[3]  T Yamamoto,et al.  Charge echo in a cooper-pair box. , 2002, Physical review letters.

[4]  P. M. Horn,et al.  Low-frequency fluctuations in solids: 1/f noise , 1981 .

[5]  J. Bernamont,et al.  Fluctuations de potentiel aux bornes d'un conducteur métallique de faible volume parcouru par un courant , 1937 .

[6]  T Yamamoto,et al.  Quantum noise in the josephson charge qubit. , 2004, Physical review letters.

[7]  G. Falci,et al.  Initial decoherence in solid state qubits. , 2005, Physical review letters.

[8]  V. Kozub,et al.  Disorder-Induced Low-Frequency Noise in Small Systems: Point and Tunnel Contacts in the Normal and Superconducting State , 1989 .

[9]  P. Joyez,et al.  Decoherence in a superconducting quantum bit circuit , 2005 .

[10]  P. Joyez,et al.  Manipulating the Quantum State of an Electrical Circuit , 2002, Science.

[11]  Ericka Stricklin-Parker,et al.  Ann , 2005 .

[12]  F. Bloch,et al.  Generalized Theory of Relaxation , 1957 .

[13]  Alfred G. Redfield,et al.  On the Theory of Relaxation Processes , 1957, IBM J. Res. Dev..

[14]  On the low-frequency current 1/f noise in metals , 1984 .

[15]  D. Averin,et al.  Qubit decoherence by Gaussian low-frequency noise , 2004, cond-mat/0401519.

[16]  John Clarke,et al.  Decoherence in Josephson-Junction Qubits due to Critical Current Fluctuations , 2004 .

[17]  Kouwenhoven,et al.  Double quantum dots as detectors of high-frequency quantum noise in mesoscopic conductors , 1999, Physical review letters.

[18]  Rosario Fazio,et al.  Decoherence and 1/f noise in Josephson qubits. , 2002, Physical review letters.

[19]  Philip Stamp,et al.  Theory of the spin bath , 2000 .

[20]  R. J. Schoelkopf,et al.  Qubits as Spectrometers of Quantum Noise , 2003 .