Entanglement Sudden Death in a Quantum Memory

TL;DR

This paper investigates how sudden entanglement loss, known as entanglement sudden death (ESD), impacts the effectiveness of quantum memories like decoherence free subspaces and noiseless subsystems, revealing little correlation between entanglement loss and information fidelity.

Contribution

It demonstrates that complete entanglement loss does not necessarily impair quantum memory fidelity, challenging assumptions about entanglement's role in quantum information protection.

Findings

No correlation between entanglement sudden death and fidelity loss.

Quantum protocols can remain effective despite ESD.

Entanglement measures like negativity and concurrence used to analyze dynamics.

Abstract

I explore entanglement dynamics in examples of quantum memories, decoherence free subspaces (DFS) and noiseless subsystems (NS), to determine how a complete loss of entanglement affects the ability of these techniques to protect quantum information. Using negativity and concurrence as entanglement measures, I find that in general there is no correlation between the complete loss of entanglement in the system and the fidelity of the stored quantum information. These results complement previous results in which quantum protocols not explictly based on entanglement exhibit little correlation between ESD and the accuracy of the given protocol.