Correlated flux noise and decoherence in two inductively coupled flux qubits

TL;DR

This study investigates how correlated flux noise affects decoherence in two inductively coupled flux qubits, revealing the role of local fluctuations and flux sensitivities in dephasing.

Contribution

It provides a detailed analysis of flux noise correlations and their impact on decoherence in coupled flux qubits, highlighting the influence of local fluctuations.

Findings

Dephasing rate varies with flux bias conditions.

Flux noise is predominantly due to local fluctuations.

Correlations in flux noise influence qubit decoherence.

Abstract

We have studied decoherence in a system where two Josephson-junction flux qubits share a part of their superconducting loops and are inductively coupled. By tuning the flux bias condition, we control the sensitivities of the energy levels to flux noises in each qubit. The dephasing rate of the first excited state is enhanced or suppressed depending on the amplitudes and the signs of the sensitivities. We have quantified the $1/f$ flux noises and their correlations and found that the dominant contribution is by local fluctuations.