Steady-state entanglement production in a quantum thermal machine with continuous feedback control

TL;DR

This paper demonstrates that continuous feedback control in a quantum thermal machine can significantly enhance steady-state entanglement, enabling violations of Bell inequalities and supporting quantum teleportation, even under non-ideal conditions.

Contribution

It introduces a feedback protocol that improves entanglement quality in a two-qubit thermal machine, surpassing previous noisy entanglement generation methods.

Findings

Entanglement can violate Bell inequalities with feedback control.

Heat current is proportional to entanglement concurrence.

Robust entanglement production under non-ideal conditions.

Abstract

Quantum thermal machines can generate steady-state entanglement by harvesting spontaneous interactions with local environments. However, using minimal resources and control, the entanglement is typically very noisy. Here, we study entanglement generation in a two-qubit quantum thermal machine in the presence of a continuous feedback protocol. Each qubit is measured continuously and the outcomes are used for real-time feedback to control the local system-environment interactions. We show that there exists an ideal operation regime where the quality of entanglement is significantly improved, to the extent that it can violate standard Bell inequalities and uphold quantum teleportation. In particular, we find, for ideal operation, that the heat current across the system is proportional to the entanglement concurrence. Finally, we investigate the robustness of entanglement production when the machine operates away from the ideal conditions.