Entanglement dynamics in superconducting qubits affected by local bistable impurities

TL;DR

This paper investigates how bistable impurities causing random telegraph noise influence entanglement in superconducting qubits, revealing a crossover from exponential decay to revivals depending on coupling parameters and initial conditions.

Contribution

It introduces a detailed analysis of entanglement dynamics under RTN in superconducting qubits, highlighting the role of the coupling ratio g and initial conditions in entanglement revival phenomena.

Findings

Threshold g_th separates exponential decay and revivals.

Initial RTN conditions affect qualitative behavior.

Strong coupling can enhance entanglement revivals.

Abstract

We study the entanglement dynamics for two independent superconducting qubits each affected by a bistable impurity generating random telegraph noise (RTN) at pure dephasing. The relevant parameter is the ratio $g$ between qubit-RTN coupling strength and RTN switching rate, that captures the physics of the crossover between Markovian and non-Markovian features of the dynamics. For identical qubit-RTN subsystems, a threshold value $g_\mathrm{th}$ of the crossover parameter separates exponential decay and onset of revivals; different qualitative behaviors also show up by changing the initial conditions of the RTN. We moreover show that, for different qubit-RTN subsystems, when both qubits are very strongly coupled to the RTN an increase in entanglement revival amplitude may occur during the dynamics.