Demonstration of microwave single-shot quantum key distribution

TL;DR

This paper demonstrates a microwave quantum key distribution protocol using superconducting devices, achieving unconditional security and showing potential for secure quantum communication over short and long distances.

Contribution

The first experimental realization of a continuous-variable microwave QKD protocol with unconditional security using superconducting parametric devices.

Findings

Achieved secure microwave QKD over 80 meters in open air

Demonstrated secure communication over 1000 meters in cryogenic conditions

Showed security can be enhanced by adding trusted noise

Abstract

Security of modern classical data encryption often relies on computationally hard problems, which can be trivialized with the advent of quantum computers. A potential remedy for this is quantum communication which takes advantage of the laws of quantum physics to provide secure exchange of information. Here, quantum key distribution (QKD) represents a powerful tool, allowing for unconditionally secure quantum communication between remote parties. At the same time, microwave quantum communication is set to play an important role in future quantum networks because of its natural frequency compatibility with superconducting quantum processors and modern near-distance communication standards. To this end, we present an experimental realization of a continuous-variable QKD protocol based on propagating displaced squeezed microwave states. We use superconducting parametric devices for generation and single-shot quadrature detection of these states. We demonstrate unconditional security in our experimental microwave QKD setting. We show that security performance can be improved by adding finite trusted noise to the preparation side. Our results indicate feasibility of secure microwave quantum communication with the currently available technology in both open-air (up to $\sim$ 80 m) and cryogenic (over 1000 m) conditions.