Generating and protecting correlated quantum states under collective dephasing

TL;DR

This paper investigates how collective dephasing affects correlated quantum states of atomic qubits, focusing on generating high-rank states, their robustness, and phenomena like time-invariant entanglement, with implications for quantum information.

Contribution

It introduces a geometric analysis of bipartite state correlations under collective dephasing and explores conditions for entanglement robustness and invariance.

Findings

High correlation rank states can be generated via dephasing.

Certain initial states exhibit time-invariant entanglement.

The geometric approach clarifies the robustness of quantum correlations.

Abstract

We study the collective dephasing process of a system of non-interacting atomic qubits, immersed in a spatially uniform magnetic field of fluctuating intensity. The correlation properties of bipartite states are analysed based on a geometric representation of the state space. Particular emphasis is put on the dephasing-assisted generation of states with a high correlation rank, which can be related to discord-type correlations and allow for direct applications in quantum information theory. Finally we study the conditions that ensure the robustness of initial entanglement and discuss the phenomenon of time-invariant entanglement.