Measuring the entanglement of coupled spins by multiphoton interference

TL;DR

This paper introduces an experimental technique to quantify entanglement between coupled spins in quantum dots using multiphoton interference, enabling comprehensive state characterization through photon correlation measurements.

Contribution

It presents a novel method leveraging multiphoton interference patterns to measure entanglement in coupled quantum dot spins, allowing complete state retrieval with fewer measurements.

Findings

The method can measure entanglement via multiphoton interference.

It enables retrieving all amplitudes of a many-qubit state.

Single or multiple correlation measurements suffice for full state characterization.

Abstract

We propose an experimental method to measure the entanglement of coupled spins, each in a separate quantum dot, by means of multiphoton interference patterns generated through the scattering of two laser beams off the quantum dots. We calculate the N-photon quantum correlations measured by N detectors on an image plane. Using two perpendicular laser beams, either many correlation measurements on a time ensemble or a single correlation measurement on a spatial ensemble of the many-qubit state is sufficient to retrieve all the possible amplitudes of a many-qubit state.