Driven two-level systems as a minimal resource for remote entanglement stabilization

TL;DR

This paper investigates how driven two-level systems can serve as minimal resources for remote entanglement stabilization, providing a framework to quantify and optimize entanglement distribution using photon sources.

Contribution

It develops a general framework to quantify maximum entanglement achievable with photon sources and evaluates the potential of driven two-level systems for autonomous entanglement distribution.

Findings

Entanglement can be distributed via Mollow sidebands of a two-level system.

Additional filter cavities improve stabilization of near-maximal entanglement.

Optimized parameters and an effective two-mode squeezing model explain entanglement limits.

Abstract

We analyze the autonomous stabilization of remote entanglement by driving two distant qubits with the output of a correlated photon source. By treating the qubits as idealized entanglement detectors, we develop a general framework to quantify the maximum amount of entanglement that can be remotely stabilized in this way with a given photon source. We then apply this approach to evaluate the suitability of a single driven two-level system as a minimal resource for autonomous entanglement distribution schemes. While our analysis confirms the presence of distributable entanglement in the Mollow sidebands of a bare two-level system, we show that stabilizing close to maximally entangled states requires additional filter cavities that enhance the relevant correlated emission events compared to other processes. We identify optimized driving and cavity parameters and explain the achievable amount of entanglement in different regimes in terms of an effective two-mode squeezing model. These insights are particularly relevant for quantum networks based on photons or phonons in solid-state systems, where isolated spins, impurity centers, or other two-level defects are readily available, while alternative sources of correlated photons are difficult to realize.