Local expansion of photonic W state using a polarization dependent beamsplitter

TL;DR

This paper introduces a probabilistic optical gate that uses a polarization-dependent beamsplitter and an ancilla photon to expand polarization entangled W states, demonstrating feasibility with current quantum optical technology.

Contribution

It presents a novel, simple probabilistic scheme for expanding W states using a polarization-dependent beamsplitter and an ancilla photon, feasible with current technology.

Findings

The scheme can probabilistically expand N-photon W states to (N+1)-photon states.

Feasibility analysis shows the method is practical with existing quantum optical components.

The approach simplifies the process of generating larger entangled W states.

Abstract

We propose a simple probabilistic optical gate to expand polarization entangled W states. The gate uses one polarization-dependent beamsplitter and a horizontally polarized single photon as an ancilla. The gate post-selectively expands $N$-photon W states to $(N+1)$-photon W states. A feasibility analysis considering the realistic experimental conditions show that the scheme is within the reach of the current quantum optical technologies.