Group transformations and entangled-state quantum gates with directionally unbiased linear-optical multiports

TL;DR

This paper introduces directionally unbiased linear-optical multiports that enable novel quantum information processing by imposing group structures on entangled states and acting as universal Bell-state processors for probabilistic quantum gates.

Contribution

It presents the concept and implementation of directionally unbiased multiports, demonstrating their potential for advanced quantum information processing and optical scattering on arbitrary graphs.

Findings

Multiports can impose group structures on Bell states

They act as universal Bell-state processors

Enable optical scattering on arbitrary graphs

Abstract

The concept of directionally unbiased optical multiports is introduced, in which photons may reflect back out the input direction. A linear-optical implementation is described, and the simplest three-port version studied. Symmetry arguments demonstrate potential for unusual quantum information processing applications. The devices impose group structures on two-photon entangled Bell states and act as universal Bell-state processors to implement probabilistic quantum gates acting on state symmetries. These multiports allow optical scattering experiments to be carried out on arbitrary undirected graphs via linear optics and raise the possibility of linear-optical information processing using group structures formed by optical qudit states.