Heralded preparation of polarization entanglement via quantum scissors

TL;DR

This paper introduces a heralded scheme for preparing polarization entanglement in photons using quantum scissors, avoiding postselection and enabling more practical quantum information applications.

Contribution

It proposes a novel heralded entanglement generation method employing quantum scissors, with two implementations and practical considerations.

Findings

Two implementations of quantum scissors are analyzed.

The scheme enables heralded polarization entanglement without postselection.

Practical aspects and advantages of the methods are discussed.

Abstract

Quantum entanglement is at the heart of quantum information sciences and quantum technologies. In the optical domain, the most common type of quantum entanglement is polarization entanglement, which is usually created in a postselection manner involving destructive photon detection and thus hindering further applications which require readily available entanglement resources. In this work, we propose a scheme to prepare multipartite entangled states of polarized photons in a heralded manner, i.e., without postselection. We exploit the quantum scissors technique to truncate a given continuous-variable entanglement into the target entangled states which are of hybrid discrete-continuous or solely discrete types. We consider two implementations of the quantum scissors: one modified from the original quantum scissors [Pegg et al., Phys. Rev. Lett. 81, 1604 (1998)] using single photons and linear optics and the other designed here using a type-II two-mode squeezer. We clarify the pros and cons of these two implementations as well as discussing practical aspects of the entanglement preparation. Our work illustrates an interface between various types of optical entanglement and the proposed quantum scissors techniques could serve as alternative methods for heralded generation of polarization entanglement.