Heralded Bell State of Dissipative Qubits Using Classical Light in a Waveguide

TL;DR

This paper demonstrates a method to generate heralded Bell states of dissipative qubits in a 1D waveguide using classical light and continuous monitoring, challenging the notion that dissipation destroys quantum coherence.

Contribution

It introduces a novel approach to produce heralded Bell states in dissipative qubits via classical light and photon detection in a 1D system, with potential applications in quantum networks.

Findings

Heralded Bell states can be generated in dissipative qubits using classical light.

Continuous measurement enables the creation of pure entangled states despite dissipation.

The method is robust even with strong classical coherent input.

Abstract

Maximally entangled two-qubit states (Bell states) are of central importance in quantum technologies. We show that heralded generation of a maximally entangled state of two intrinsically open qubits can be realized in a one-dimensional (1d) system through strong coherent driving and continuous monitoring. In contrast to the natural idea that dissipation leads to decoherence and so destroys quantum effects, continuous measurement and strong interference in our 1d system generate a pure state with perfect quantum correlation between the two open qubits. Though the steady state is a trivial product state which has zero coherence or concurrence, we show that, with carefully tuned parameters, a Bell state can be generated in the system's quantum jump trajectories, heralded by a reflected photon. Surprisingly, this maximally entangled state survives the strong coherent state input---a classical state that overwhelms the system. This simple method to generate maximally entangled states using classical coherent light and photon detection may, since our qubits are in a 1d continuum, find application as a building block of quantum networks.