Entanglement Meter: Estimation of entanglement with single copy in Interferometer

TL;DR

This paper introduces an interferometric method using a Mach-Zehnder setup to efficiently detect and quantify entanglement in bipartite quantum states with a single copy, including pure and mixed states.

Contribution

It demonstrates how to measure entanglement metrics like linear entropy and negativity directly from interference visibility, without complex local measurements.

Findings

Interference visibility directly measures entanglement in two-qubit pure states.

Mutual predictability can be obtained from intensity patterns without local basis measurements.

Entanglement witness operators can be implemented in an interferometric setup.

Abstract

Efficient certification and quantification of high dimensional entanglement of composite systems are challenging both theoretically as well as experimentally. Here, we demonstrate that several entanglement detection methods can be implemented efficiently in a Mach-Zehnder Interferometric set-up. In particular, we demonstrate how to measure the linear entropy and the negativity of bipartite systems from the visibility of Mach-Zehnder interferometer using single copy of the input state. Our result shows that for any two qubit pure bipartite state, the interference visibility is a direct measure of entanglement. We also propose how to measure the mutual predictability experimentally from the intensity patterns of the interferometric set-up without having to resort to local measurements of mutually unbiased bases. Furthermore, we show that the entanglement witness operator can be measured in a interference setup and the phase shift is sensitive to the separable or entangled nature of the state. Our proposals bring out the power of Interferometric set-up in entanglement detection of pure and several mixed states which paves the way towards design of entanglement meter.