Generating multi-photon W-like states for perfect quantum teleportation and superdense coding

TL;DR

This paper presents a simple, efficient optical scheme for generating large-scale W-like entangled states, crucial for perfect quantum teleportation and superdense coding, using existing photonics technology without ancilla photons or controlled gates.

Contribution

It introduces a novel, resource-efficient method for preparing W-like states via fusion and expansion, outperforming methods using maximally entangled W states.

Findings

Fusion mechanism is more efficient with W-like states for large-scale generation.

The scheme requires no ancilla photons or controlled gates.

It can be implemented with current photonics technology.

Abstract

An interesting aspect of multipartite entanglement is that for perfect teleportation and superdense coding, not the maximally entangled W states but a special class of non-maximally entangled W-like states are required. Therefore, efficient preparation of such W-like states is of great importance in quantum communications, which has not been studied as much as the preparation of W states. In this letter, we propose a simple optical scheme for efficient preparation of large-scale polarization based entangled W-like states by fusing two W-like states or expanding a W-like state with an ancilla photon. Our scheme can also generate large-scale W states by fusing or expanding W or even W-like states. The cost analysis show that in generating large scale W states, the fusion mechanism achieves a higher efficiency with non-maximally entangled W-like states than maximally entangled W states. Our scheme can also start fusion or expansion with Bell states, and it is composed of a polarization dependent beam splitter, two polarizing beam splitters and photon detectors. Requiring no ancilla photons or controlled gates to operate, our scheme can be realized with the current photonics technology and we believe it enables advances in quantum teleportation and superdense coding in multipartite settings.