Proof-of-principle demonstration of measurement-device-independent quantum key distribution using polarization qubits

TL;DR

This paper demonstrates a proof-of-principle of measurement-device-independent quantum key distribution using polarization qubits over optical fibers, achieving secure key generation with polarization stabilization and Bell-state analysis.

Contribution

It presents the first experimental implementation of MDI-QKD with polarization qubits over fiber links, including polarization stabilization and Bell-state measurement.

Findings

Secret-key rate of 1.04x10^-6 bits/pulse achieved

Polarization stabilization effectively maintained qubit integrity

Successful demonstration of MDI-QKD over 8.5 km fiber links

Abstract

We perform a proof-of-principle demonstration of the measurement-device-independent quantum key distribution (MDI-QKD) protocol using weak coherent states and polarization-encoded qubits over two optical fiber links of 8.5 km each. Each link was independently stabilized against polarization drifts using a full-polarization control system employing two wavelength-multiplexed control channels. A linear-optics-based polarization Bell-state analyzer was built into the intermediate station, Charlie, which is connected to both Alice and Bob via the optical fiber links. Using decoy-states, a lower bound for the secret-key generation rate of 1.04x10^-6 bits/pulse is computed.