Preparation of entangled states of two photons in several spatial modes

TL;DR

This paper presents a protocol for preparing arbitrary entangled states of two photons across multiple spatial modes, utilizing linear optics, photon pairs, and post-selection, with optimization for success probability.

Contribution

It introduces a novel protocol combining unitary and non-unitary transformations for flexible entangled state preparation in linear optics.

Findings

Protocol successfully prepares arbitrary two-photon states in multiple modes.

Optimization techniques improve the success probability of state preparation.

Feasible scheme for generating entangled states for quantum computing applications.

Abstract

We describe a protocol capable of preparing an arbitrary state of two photons in several spatial modes using pairs of photons generated by spontaneous parametric down-conversion, linear optical elements and single-photon detectors or post-selection. The protocol involves unitary and non-unitary transformations realizable by beam splitters and phase shifters. Non-unitary transformations are implemented by attenuation filters. The protocol contains several optimization capabilities with the goal of improving overall probability of its success. We also show how entangled two-photon states required for quantum computing with linear optics can be prepared using a very simple and feasible scheme.