Dynamics and extraction of quantum discord in a multipartite open system

TL;DR

This paper studies how quantum discord, a form of quantum correlation, transfers within a multipartite open quantum system of qubits, cavities, and reservoirs, and how it can be extracted and transferred via leaking photons.

Contribution

It introduces a detailed analysis of quantum discord dynamics in a complex open system and demonstrates its transfer and extraction mechanisms.

Findings

Quantum discord transfers from qubits to cavities and reservoirs.

Quantum discord can be extracted and transferred via leaking photons.

Cavities may not need to be entangled for discord transfer.

Abstract

We consider a multipartite system consisting of two noninteracting qubits each embedded in a single-mode leaky cavity, in turn connected to an external bosonic reservoir. Initially, we take the two qubits in an entangled state while the cavities and the reservoirs have zero photons. We investigate, in this six-partite quantum system, the transfer of quantum discord from the qubits to the cavities and reservoirs. We show that this transfer occurs also when the cavities are not entangled. Moreover, we discuss how quantum discord can be extracted from the cavities and transferred to distant systems by traveling leaking photons, using the input-output theory.