Experimental Demonstration of Polarization Encoding Measurement-Device-Independent Quantum Key Distribution

TL;DR

This paper reports the first experimental implementation of polarization encoding measurement-device-independent quantum key distribution, demonstrating secure communication over 10 km fiber and paving the way for scalable quantum networks.

Contribution

It presents the first experimental demonstration of polarization encoding MDI-QKD with active phase randomization and optimized decoy states, enabling secure long-distance quantum communication.

Findings

Generated a 1600-bit secure key over 10 km fiber

Implemented active phase randomization to enhance security

Showed feasibility of polarization encoding MDI-QKD over large distances

Abstract

We demonstrate the first implementation of polarization encoding measurement-device-independent quantum key distribution (MDI-QKD), which is immune to all detector side-channel attacks. Active phase randomization of each individual pulse is implemented to protect against attacks on imperfect sources. By optimizing the parameters in the decoy state protocol, we show that it is feasible to implement polarization encoding MDI-QKD over large optical fiber distances. A 1600-bit secure key is generated between two parties separated by 10 km of telecom fibers. Our work suggests the possibility of building a MDI-QKD network, in which complicated and expensive detection system is placed in a central node and users connected to it can perform confidential communication by preparing polarization qubits with compact and low-cost equipment. Since MDI-QKD is highly compatible with the quantum network, our work brings the realization of quantum internet one step closer.