Measurement-device-independent entanglement detection for continuous-variable systems

TL;DR

This paper develops practical methods for detecting entanglement in continuous-variable quantum systems without relying on characterized measurement devices, enabling device-independent certification using standard optical techniques.

Contribution

It generalizes device-independent entanglement detection to continuous-variable systems and introduces a feasible protocol for Gaussian states using common optical tools.

Findings

All entangled states can be detected without device characterization.

The protocol is practical with current optical technology.

It specifically certifies entanglement of two-mode Gaussian states.

Abstract

We study the detection of continuous-variable entanglement, for which most of the existing methods designed so far require a full specification of the devices, and we present protocols for entanglement detection in a scenario where the measurement devices are completely uncharacterised. We first generalise, to the continuous variable regime, the seminal results by Buscemi [PRL 108, 200401(2012)] and Branciard et al. [PRL 110, 060405 (2013)], showing that all entangled states can bedetected in this scenario. Most importantly, we then describe a practical protocol that allows for the measurement-device-independent certification of entanglement of all two-mode entangled Gaussian states. This protocol is feasible with current technology as it makes only use of standard optical setups such as coherent states and homodyne measurements.