Entanglement invariant for the double Jaynes-Cummings model

TL;DR

This paper investigates entanglement dynamics in a four-qubit system under the double Jaynes-Cummings model, revealing an invariant that explains entanglement sudden death as a consequence of ignoring certain degrees of freedom.

Contribution

It introduces an entanglement invariant for the double Jaynes-Cummings model, linking entanglement sudden death to the tracing out of entangled degrees of freedom.

Findings

Identifies a natural entanglement invariant under system evolution.

Shows entanglement sudden death results from ignoring entangled degrees of freedom.

Compares wedge product measure with bipartite concurrence results.

Abstract

We study entanglement dynamics between four qubits interacting through two isolated Jaynes-Cummings hamiltonians, via the entanglement measure based on the wedge product. We compare the results with similar results obtained using bipartite concurrence resulting in what is referred to as "entanglement sudden death". We find a natural entanglement invariant under evolution demonstrating that entanglement sudden death is caused by ignoring (tracing over) some of the system's degrees of freedom that become entangled through the interaction.