Polarization-orbital angular momentum duality assisted entanglement observation for indistinguishable photons

TL;DR

This paper demonstrates the duality in entanglement of indistinguishable photons between polarization and orbital angular momentum variables, providing a method to verify quantum indistinguishability and potential applications in quantum sensing.

Contribution

It introduces a duality-assisted approach to observe entanglement in different variables of indistinguishable photons, advancing quantum communication verification methods.

Findings

Polarization entanglement observed via OAM basis sorting.

OAM entanglement revealed through polarization mode sorting.

Duality-assisted entanglement observation can verify quantum indistinguishability.

Abstract

Duality in the entanglement of identical particles manifests that entanglement in only one variable can be revealed at a time. We demonstrate this using polarization and orbital angular momentum (OAM) variables of indistinguishable photons generated from parametric down conversion. We show polarization entanglement by sorting photons in even and odd OAM basis, while sorting them in two orthogonal polarization modes reveals the OAM entanglement. The duality assisted observation of entanglement can be used as a verification for the preservation of quantum indistinguishability over communication channels. Indistinguishable photons entangled in complementary variables could also evoke interest in distributed quantum sensing protocols and remote entanglement generation.