Dephasing of qubits by transverse low-frequency noise

TL;DR

This paper investigates how low-frequency transverse noise affects qubit coherence, revealing that it acts like quadratic longitudinal noise and deriving decay laws for quantum oscillations under various noise conditions.

Contribution

It demonstrates the equivalence of transverse low-frequency noise to quadratic longitudinal coupling and derives decay laws for quantum coherence.

Findings

Transverse low-frequency noise behaves like quadratic longitudinal coupling.

Decay laws for quantum oscillations are derived under combined noise influences.

Results are relevant for understanding decoherence in superconducting qubits.

Abstract

We analyze the dissipative dynamics of a two-level quantum system subject to low-frequency, e.g. 1/f noise, motivated by recent experiments with superconducting quantum circuits. We show that the effect of transverse linear coupling of the system to low-frequency noise is equivalent to that of quadratic longitudinal coupling. We further find the decay law of quantum coherent oscillations under the influence of both low- and high-frequency fluctuations, in particular, for the case of comparable rates of relaxation and pure dephasing.