Quantum error correction may delay, but also cause, entanglement sudden death

TL;DR

This paper investigates how quantum error correction influences entanglement sudden death, revealing it can both delay and inadvertently cause ESD, with fidelity not always reflecting entanglement preservation.

Contribution

It demonstrates that quantum error correction can both delay and induce entanglement sudden death, highlighting limitations of fidelity as a measure of entanglement.

Findings

Quantum error correction can delay ESD in some cases.

Quantum error correction may cause ESD in other cases.

Fidelity is not always a reliable indicator of entanglement preservation.

Abstract

Dissipation may cause two initially entangled qubits to evolve into a separable state in a finite time. This behavior is called entanglement sudden death (ESD). We study to what extent quantum error correction can combat ESD. We find that in some cases quantum error correction can delay entanglement sudden death but in other cases quantum error correction may cause ESD for states that otherwise do not suffer from it. Our analysis also shows that fidelity may not be the best measure to compare the efficiency of different error correction codes since the fidelity is not directly coupled to a state's remaining entanglement.