Generation of a bright four-photon entangled state from a warm atomic ensemble via inherent polarization entanglement

Jiho Park,Han Seb Moon

doi:10.1063/5.0076851

Abstract

We report the stable generation of a bright four-photon polarization-entangled Greenberger–Horne–Zeilinger (GHZ) state obtained by the spatial multiplexing of inherently polarization-entangled photons from a warm atomic ensemble of 87Rb. Owing to the total angular momentum conservation of the atomic state in the spontaneous four-wave mixing process of a cascade-type atomic system, the polarizations of the signal and idler photons in the two-photon decay are entangled. With a Rb vapor cell, we realize the generation of robust and bright four-photon GHZ states using two symmetrical spatial modes of inherently polarization-entangled photon pairs without applying an interferometric configuration. The four-photon average coincidence rate of the GHZ state with a fidelity of 0.88(2) is measured as 1.69(7) Hz under a weak pump power of 10 μW. The minimum Allan variance for the stability of the four-photon GHZ state is estimated as 0.92° for an average time of 10 h.

Highlights

For effective atom–photon interactions, the optical frequency and spectral width of the photons should satisfy the requirements of the interacting atoms
We report the stable generation of a bright four-photon polarization-entangled Greenberger–Horne–Zeilinger (GHZ) state obtained by the spatial multiplexing of inherently polarization-entangled photons from a warm atomic ensemble of 87Rb
The optimal scenario is that the entangled photons are emitted from the atom that is used for quantum memory

Summary

Introduction

For effective atom–photon interactions, the optical frequency and spectral width of the photons should satisfy the requirements of the interacting atoms. Scitation.org/journal/apl on a spatially multiplexed heralded source of single photons with high quality and high detection rates.[34] the direct generation of robust and efficient polarization-entangled photon pairs has been experimentally demonstrated via the interesting polarization correlation of decay channels of the Zeeman substates in a cascade-type atomic system.[36]

Results

Conclusion