Witnessing single-photon entanglement with local homodyne measurements: analytical bounds and robustness to losses

TL;DR

This paper analyzes a local homodyne measurement-based entanglement witness for single-photon entanglement, providing analytical bounds and demonstrating its robustness to losses, emphasizing the potential of hybrid optical methods in quantum networks.

Contribution

It introduces analytical bounds for the entanglement witness and experimentally confirms its robustness to losses, advancing hybrid quantum measurement techniques.

Findings

Analytical bounds for the entanglement witness are derived.

Experimental results confirm robustness against losses.

Hybrid optical methods effectively characterize discrete entanglement.

Abstract

Single-photon entanglement is one of the primary resources for quantum networks, including quantum repeater architectures. Such entanglement can be revealed with only local homodyne measurements through the entanglement witness presented in [Morin et al. Phys. Rev. Lett. 110, 130401 (2013)]. Here, we provide an extended analysis of this witness by introducing analytical bounds and by reporting measurements confirming its great robustness with regard to losses. This study highlights the potential of optical hybrid methods, where discrete entanglement is characterized through continuous-variable measurements.