Photon-assisted entanglement creation by minimum-error generalized quantum measurements in the strong coupling regime

TL;DR

This paper investigates entangling two distant qubits using strong quantum electrodynamical coupling and optimized quantum measurements, enabling high-fidelity Bell state creation with minimal error, even considering photon loss.

Contribution

It introduces a method for entangling qubits via optimal generalized measurements in the strong-coupling regime, overcoming limitations of weak coupling scenarios.

Findings

High-fidelity Bell states achievable with near-unity fidelity in ideal conditions.

Effective entanglement creation persists despite photon loss.

Strong coupling allows for high success rates and repetition frequencies.

Abstract

We explore possibilities of entangling two distant material qubits with the help of an optical radiation field in the regime of strong quantum electrodynamical coupling with almost resonant interaction. For this purpose the optimum generalized field measurements are determined which are capable of preparing a two-qubit Bell state by postselection with minimum error. It is demonstrated that in the strong-coupling regime some of the recently found limitations of the non-resonant weak-coupling regime can be circumvented successfully due to characteristic quantum electrodynamical quantum interference effects. In particular, in the absence of photon loss it is possible to postselect two-qubit Bell states with fidelities close to unity by a proper choice of the relevant interaction time. Even in the presence of photon loss this strong-coupling regime offers interesting perspectives for creating spatially well-separated Bell pairs with high fidelities, high success probabilities, and high repetition rates which are relevant for future realizations of quantum repeaters.