Entangled state generation with an intrinsically pure single-photon source and a weak coherent source

TL;DR

This paper demonstrates an experimental method to generate entangled states using a spectrally pure heralded single-photon source combined with a weak coherent state, achieving significantly higher brightness without filters, advancing quantum information applications.

Contribution

The study introduces a spectrally pure single-photon source with group-velocity matching that is 60 times brighter than previous methods, eliminating the need for bandpass filters.

Findings

Achieved a 60-fold increase in photon source brightness.

Generated entangled states suitable for quantum information protocols.

No bandpass filters required for spectral purity.

Abstract

We report on the experimental generation of an entangled state with a spectrally pure heralded single-photon state and a weak coherent state. By choosing group-velocity matching in the nonlinear crystal, our system for producing entangled photons was 60 times brighter than that in the earlier experiment [Phys. Rev. Lett. 90, 240401 (2003)], with no need of bandpass filters. This entanglement system is useful for quantum information protocols that require indistinguishable photons from independent sources.