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Noise and decoherence in quantum two-level systems

Alexander Shnirman·Yuriy Makhlin·Gerd Schön
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Abstract

Motivated by recent experiments with Josephson-junction circuits we reconsider decoherence effects in quantum two-level systems (TLS). On one hand, the experiments demonstrate the importance of 1/f noise, on the other hand, by operating at symmetry points one can suppress noise effects in linear order. We, therefore, analyze noise sources with a variety of power spectra, with linear or quadratic coupling, which are longitudinal or transverse relative to the eigenbasis of the unperturbed Hamiltonian. To evaluate the dephasing time for transverse 1/f noise second-order contributions have to be taken into account. Manipulations of the quantum state of the TLS define characteristic time scales. We discuss the consequences for relaxation and dephasing processes.

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Alexander Shnirman, Yuriy Makhlin, Gerd Schön. 2002-02-28. Noise and decoherence in quantum two-level systems. https://doi.org/10.1238/physica.topical.102a00147

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