Dynamics of correlations due to a phase noisy laser

TL;DR

This paper investigates how quantum and classical correlations evolve over time between two qubits affected by local phase noise, revealing regimes of decay and revival, and highlighting the persistence of quantum discord even when entanglement vanishes.

Contribution

It provides explicit formulas for correlation dynamics under phase noisy laser influence, identifying Markovian and non-Markovian regimes and their effects on quantum discord and entanglement.

Findings

Quantum correlations can revive in non-Markovian regimes.

Quantum discord persists even when entanglement is zero.

Correlation decay regimes depend on system parameters.

Abstract

We analyze the dynamics of various kinds of correlations present between two initially entangled independent qubits, each one subject to a local phase noisy laser. We give explicit expressions of the relevant quantifiers of correlations for the general case of single-qubit unital evolution, which includes the case of a phase noisy laser. Although the light field is treated as classical, we find that this model can describe revivals of quantum correlations. Two different dynamical regimes of decay of correlations occur, a Markovian one (exponential decay) and a non-Markovian one (oscillatory decay with revivals) depending on the values of system parameters. In particular, in the non-Markovian regime, quantum correlations quantified by quantum discord show an oscillatory decay faster than that of classical correlations. Moreover, there are time regions where nonzero discord is present while entanglement is zero.