Controllable Gaussian-qubit interface for extremal quantum state engineering

TL;DR

This paper demonstrates how bilinear interactions with Gaussian light fields can be used to precisely engineer extremally entangled two-qubit states, covering the entire entanglement-purity spectrum in realistic setups.

Contribution

It introduces a method to control two-qubit entanglement via a small set of parameters of Gaussian states, enabling extremal state engineering in practical matter-light systems.

Findings

Attainable two-qubit states cover the entire entanglement-purity region.

Maximally entangled two-qubit states correspond to maximally entangled Gaussian states.

A small parameter set suffices for extremal entanglement control.

Abstract

We study state engineering through bilinear interactions between two remote qubits and two-mode Gaussian light fields. The attainable two-qubit states span the entire physically allowed region in the entanglement-versus-global-purity plane. Two-mode Gaussian states with maximal entanglement at fixed global and marginal entropies produce maximally entangled two-qubit states in the corresponding entropic diagram. We show that a small set of parameters characterizing extremally entangled two-mode Gaussian states is sufficient to control the engineering of extremally entangled two-qubit states, which can be realized in realistic matter-light scenarios.