Experimental verification of bound and multiparticle entanglement with the randomized measurement toolbox

TL;DR

This paper experimentally verifies different types of multiparticle and weak entanglement in quantum states using randomized measurement techniques, demonstrating their effectiveness beyond strongly entangled states.

Contribution

It applies randomized measurement methods to characterize bound and multiparticle entanglement, including weakly entangled and bound entangled states, in experimental photonic systems.

Findings

Successfully characterized GHZ-W mixed states using second moments.

Verified weak entanglement in bound entangled chessboard states.

Compared randomized measurement results with traditional entanglement measures.

Abstract

In recent years, analysis methods for quantum states based on randomized measurements have been investigated extensively. Still, in the experimental implementations these methods were typically used for characterizing strongly entangled states and not to analyze the different families of multiparticle or weakly entangled states. In this work, we experimentally prepare various entangled states with path-polarization hyper-entangled photon pairs, and study their entanglement properties using the full toolbox of randomized measurements. First, we successfully characterize the correlations of a series of GHZ-W mixed states using the second moments of the random outcomes, and demonstrate the advantages of this method by comparing it with the well-known three-tangle and squared concurrence. Second, we generate bound entangled chessboard states of two three-dimensional systems and verify their weak entanglement with a criterion derived from moments of randomized measurements.