Three-qubit topological phase on entangled photon pairs

TL;DR

This paper proposes an experiment to observe topological phases in three-qubit entangled photon states, revealing nontrivial topological structures and linking specific phase shifts to genuine tripartite entanglement.

Contribution

It introduces a method to observe topological phases in three-qubit entangled states and relates these phases to the presence of genuine tripartite entanglement.

Findings

Observation of a $a/2$ phase shift as a signature of tripartite entanglement

Preparation protocols for states with different topological phases

Connection between topological phases and entanglement structure

Abstract

We propose an experiment to observe the topological phases associated with cyclic evolutions, generated by local SU(2) operations, on three-qubit entangled states prepared on different degrees of freedom of entangled photon pairs. The topological phases reveal the nontrivial topological structure of the local SU(2) orbits. We describe how to prepare states showing different topological phases, and discuss their relation to entanglement. In particular, the presence of a $\pi/2$ phase shift is a signature of genuine tripartite entanglement in the sense that it does not exist for two-qubit systems.