Direct measurement of atomic entanglement via cavity photon statistics

TL;DR

This paper presents an experimental method to directly measure atomic entanglement by analyzing cavity photon statistics, enabling entanglement quantification in distributed quantum systems without requiring both atoms to interact with the cavity.

Contribution

The proposed scheme allows entanglement measurement using only one atom's interaction with a cavity, simplifying and broadening the applicability of entanglement quantification.

Findings

Concurrence can be measured via cavity photon statistics.

The method is independent of the second atom's location.

It enables entanglement measurement in distributed systems.

Abstract

We propose an experimental scheme for the measurement of entanglement between two two-level atoms. Our scheme requires one of the two entangled atoms to interact with a cavity field dispersively, and we show that by measuring the zero time-delay second-order coherence function of the cavity field, one can measure the concurrence of an arbitrary Bell-like atomic two-qubit state. As our scheme requires only one of the atoms to interact with the measured cavity, the entanglement quantification becomes independent of the location of the other atom. Therefore, our scheme can have important implications for entanglement quantification in distributed quantum systems.