Recovering Entanglement by Local Operations

TL;DR

This paper explains how entanglement can be recovered in bipartite quantum systems through local operations by introducing the concept of hidden entanglement, especially under classical noise, without non-local actions.

Contribution

It introduces the concept of hidden entanglement to explain entanglement revivals and demonstrates recovery via local pulses in noisy two-qubit systems.

Findings

Entanglement can be recovered with local pulses under classical noise.

Hidden entanglement accounts for entanglement not exploitable due to lack of classical information.

Insights into entanglement revivals in non-Markovian dynamics.

Abstract

We investigate the phenomenon of bipartite entanglement revivals under purely local operations in systems subject to local and independent classical noise sources. We explain this apparent paradox in the physical ensemble description of the system state by introducing the concept of "hidden" entanglement, which indicates the amount of entanglement that cannot be exploited due to the lack of classical information on the system. For this reason this part of entanglement can be recovered without the action of non-local operations or back-transfer process. For two noninteracting qubits under a low-frequency stochastic noise, we show that entanglement can be recovered by local pulses only. We also discuss how hidden entanglement may provide new insights about entanglement revivals in non-Markovian dynamics.