Entanglement generation by interaction with semiclassical radiation

TL;DR

This paper investigates how entanglement between two qubits can be generated through interaction with a semiclassical radiation field, revealing that finite entanglement is possible in the classical limit with a trade-off involving interaction time and decoherence effects.

Contribution

It demonstrates the possibility of generating non-maximal entanglement via a semiclassical field and analyzes the effects of decoherence and interaction time on entanglement quality.

Findings

Finite entanglement achievable in the classical limit.

Optimal entanglement results from a trade-off involving sub-wave packet entanglement and purity.

Photon loss limits maximum entanglement, decreasing as inverse sixth power of mean photon number.

Abstract

We address a fundamental issue in quantum mechanics and quantum information theory, the generation of an entangled pair of qubits that interact solely through a third, semiclassical degree of freedom, in the framework of cavity quantum electrodynamics. We show that finite, though not maximal, entanglement is obtainable in the classical limit, at the price of a diverging effective interaction time. The optimal atomic entanglement derives from a trade-off between the atomic entanglement in a sub-wave packet and the purity of the atomic state. Decoherence by photon loss sets an upper limit on the degree of excitation of the cavity mode, beyond which the achievable entanglement decreases as the inverse mean photon number to the sixth power.