Effects of low-frequency noise cross-correlations in coupled superconducting qubits

TL;DR

This paper investigates how correlated low-frequency noise impacts the coherence of coupled superconducting qubits, revealing that noise correlations can significantly alter decoherence behavior and suggesting recalibration as a mitigation strategy.

Contribution

It introduces a phenomenological model for spatial and cross-talk noise correlations and analyzes their effects on qubit decoherence using both analytic and numerical methods.

Findings

Correlated low-frequency noise can cause qualitative changes in decoherence dynamics.

The impact of noise depends critically on its amplitude relative to qubit coupling strength.

Recalibration protocols may help reduce dephasing caused by correlated noise.

Abstract

We study the effects of correlated low frequency noise sources acting on a two qubit gate in a fixed coupling scheme. A phenomenological model for the spatial and cross-talk correlations is introduced. The decoherence inside the SWAP subspace is analysed by combining analytic results based on the adiabatic approximation and numerical simulations. Results critically depend on amplitude of the low frequency noise with respect to the qubits coupling strength. Correlations between noise sources induce qualitative different behaviors depending on the values of the above parameters. The possibility to reduce dephasing due to correlated low frequency noise by a recalibration protocol is discussed.