Informationally symmetrical Bell state preparation and measurement

TL;DR

This paper proposes a novel linear optical Bell state measurement scheme that does not require photon overlap at a beamsplitter, enabling symmetric and remote Bell state preparation for quantum communication.

Contribution

It introduces a new BSM method based on two-photon interference without photon overlap, allowing symmetric and remote Bell state preparation.

Findings

The scheme does not require photon overlap at a beamsplitter.

It enables symmetric Bell state measurement between remote parties.

It can be extended to multi-photon systems for quantum communication.

Abstract

Bell state measurement (BSM) plays crucial roles in photonic quantum information processing. The standard linear optical BSM is based on Hong-Ou-Mandel interference where two photons meet and interfere at a beamsplitter (BS). However, a generalized two-photon interference is not based on photon-photon interaction, but interference between two-photon probability amplitudes. Therefore, it might be possible to implement BSM without interfering photons at a BS. Here, we investigate a linear optical BSM scheme which does not require two photon overlapping at a BS. By unleashing the two photon coexistence condition, it can be symmetrically divided into two parties. The symmetrically dividable property suggests informationally symmetrical BSM between remote parties without a third party. We also present that our BSM scheme can be used for Bell state preparation between remote parties without a third party. Since our BSM scheme can be easily extended to multiple photons, it can be useful for various quantum communication applications.