Quantum steering with vector vortex photon states with the detection loophole closed

TL;DR

This paper demonstrates loophole-free quantum steering using vector vortex photon states entangled in orbital angular momentum and polarization, enabling advanced quantum communication and fundamental tests of quantum physics.

Contribution

It is the first to close the detection loophole in quantum steering with vector vortex states, expanding quantum nonlocality verification beyond polarization entanglement.

Findings

Loophole-free quantum steering achieved with vector vortex photons.

Demonstrates high-efficiency encoding beyond polarization.

Enables potential for satellite-based secure quantum communication.

Abstract

Violating a nonlocality inequality enables the most powerful remote quantum information tasks and fundamental tests of quantum physics. Loophole-free photonic verification of nonlocality has been achieved with polarization-entangled photon pairs, but not with states entangled in other degrees of freedom. Here we demonstrate completion of the quantum steering nonlocality task, with the detection loophole closed, when entanglement is distributed by transmitting a photon in an optical vector vortex state, formed by optical orbital angular momentum (OAM) and polarization. As well as opening up a high-efficiency encoding beyond polarization, the critically-important demonstration of vector vortex steering opens the door to new free-space and satellite-based secure quantum communication devices and device-independent protocols.