Backaction driven, robust, steady-state long-distance qubit entanglement over lossy channels

TL;DR

This paper introduces a reservoir engineering scheme for creating stable, long-distance entanglement between non-interacting qubits over lossy channels, using correlated decay to achieve robustness and high fidelity.

Contribution

The authors propose a simple, generic protocol leveraging correlated decay for robust entanglement generation without dynamic control or feedback, effective over lossy channels.

Findings

High-quality entanglement solutions over a wide parameter range

Robustness against noise, miscalibration, and channel loss

Quadratic suppression of infidelity through bi-directional decay

Abstract

We present a scheme for generating robust and persistent entanglement between qubits that do not interact and that are separated by a long and lossy transmission channel, using Markovian reservoir engineering. The proposal uses only the correlated decay into the common channel of remotely separated, driven single-photon qubit transitions. This simple scheme is generic and applicable to various experimental implementations, including circuit and cavity QED, with little experimental overhead compared with methods requiring dynamic control, initialization, measurement, or feedback. In addition to avoiding these inefficiencies, the simple protocol is highly robust against noise, miscalibration, and loss in the channel. We find high quality solutions over a wide range of parameters and show that the optimal strategy reflects a transition from ballistic to diffusive photon transmission, going from symmetrically and coherently driving a common steady state to asymmetrically absorbing photons that are emitted from one qubit by the second. Detailed analysis of the role of the transmission channel shows that allowing bi-directional decay drastically increases indistinguishability and thereby quadratically suppresses infidelity.