Compact implementation of high-dimensional mutually partially unbiased bases protocol

Abstract

Transverse spatial mode of light is crucial in high-dimensional quantum key distribution (QKD). However, applications in realistic scenarios suffer from mode-dependent loss and the complexity of system, making it impractical to achieve higher-dimensional, longer-distance and low-cost communications. A mutually partially unbiased bases (MPUBs) protocol has been proposed to fundamentally eliminate the effects induced by mode-dependent loss for long propagation distances and limited sizes of apertures. Here, we demonstrate the first implementation of the MPUBs protocol in dimensions of d = 2, 4, 5 and 6. By performing a controlled unitary transformation, we can actively switch the measurement basis and enable a compact measurement system. In consequence, a higher encoding dimension is available under finite system resources, resulting in higher key rates and stronger noise resistance. Our work enhances the practicability of MPUBs protocol, and may promote the applications of high-dimensional QKD in quantum networks.

An intelligent threshold selection method to improve orbital angular momentum-encoded quantum key distribution under turbulence

“…To break through the system information entropy threshold, high-dimensional QKD (HD-QKD) offers improved com-munication capacity and enhanced noise resilience [9][10][11][12][13][14]. One common approach to achieve HD-QKD is through the utilization of the orbital angular momentum (OAM) of photons [15][16][17][18][19]. The OAM freedom allows photons to be mapped to an infinite dimensional Hilbert space, providing an effective resource for implementing HD-QKD.…”