Robustness of quantum discord to sudden death

TL;DR

This paper investigates how quantum discord remains more resilient than entanglement under various dissipative environments, suggesting quantum algorithms based on discord could be more robust against decoherence.

Contribution

It provides a comparative analysis of quantum discord and entanglement dynamics under different Markovian noise channels, highlighting discord's robustness.

Findings

Quantum discord vanishes only asymptotically, unlike entanglement which can undergo sudden death.

Quantum discord remains non-zero at finite temperatures even when entanglement disappears.

Quantum discord's robustness suggests advantages for discord-based quantum algorithms.

Abstract

We calculate the dissipative dynamics of two-qubit quantum discord under Markovian environments. We analyze various dissipative channels such as dephasing, depolarizing, and generalized amplitude damping, assuming independent perturbation, in which each qubit is coupled to its own channel. Choosing initial conditions that manifest the so-called sudden death of entanglement, we compare the dynamics of entanglement with that of quantum discord. We show that in all cases where entanglement suddenly disappears, quantum discord vanishes only in the asymptotic limit, behaving similarly to individual decoherence of the qubits, even at finite temperatures. Hence, quantum discord is more robust than the entanglement against to decoherence so that quantum algorithms based only on quantum discord correlations may be more robust than those based on entanglement.