Quantification of Concurrence via Weak Measurement

TL;DR

This paper introduces a novel protocol using weak measurements and optical techniques to quantify the entanglement measure concurrence in two-qubit pure states without needing multiple copies.

Contribution

It presents a universal, single-measurement protocol for quantifying concurrence in two-qubit states, avoiding the need for multiple state copies.

Findings

Protocol successfully quantifies concurrence in two-qubit states.

Applicable to all two-qubit pure states without multiple copies.

Explicit optical implementation demonstrated.

Abstract

Since entanglement is not an observable per se, measuring its value in practice is a difficult task. Here we propose a protocol for quantifying a particular entanglement measure, namely concurrence, of an arbitrary two-qubit pure state via a single fixed measurement set-up by exploiting so-called weak measurements and the associated weak values together with the properties of the Laguerre-Gaussian modes. The virtue of our technique is that it is generally applicable for all two-qubit systems and does not involve simultaneous copies of the entangled state. We also propose an explicit optical implementation of the protocol.