Spin-echo entanglement protection from random telegraph noise

TL;DR

This paper investigates how spin-echo techniques can protect entanglement between two qubits affected by non-Gaussian random telegraph noise, revealing complex dynamics and potential for entanglement preservation.

Contribution

It provides an analytic model of entanglement dynamics under telegraph noise and identifies conditions where spin-echo can effectively delay entanglement loss.

Findings

Spin-echo can delay entanglement decay.

It can cancel entanglement revivals and dark periods.

Plateau-like behaviors of concurrence are observed.

Abstract

We analyze local spin-echo procedures to protect entanglement between two non-interacting qubits, each subject to pure-dephasing random telegraph noise. For superconducting qubits this simple model captures characteristic features of the effect of bistable impurities coupled to the device. An analytic expression for the entanglement dynamics is reported. Peculiar features related to the non-Gaussian nature of the noise already observed in the single qubit dynamics also occur in the entanglement dynamics for proper values of the ratio $g=v/\gamma$, between the qubit-impurity coupling strength and the switching rate of the random telegraph process, and of the separation between the pulses $\Delta t$. We find that the echo procedure may delay the disappearance of entanglement, cancel the dynamical structure of entanglement revivals and dark periods, and induce peculiar plateau-like behaviors of the concurrence.