High-dimensional quantum key distribution using orbital angular momentum of single photons from a colloidal quantum dot at room temperature

TL;DR

This paper demonstrates a high-dimensional quantum key distribution system using a room-temperature colloidal quantum dot as a deterministic single-photon source, encoding information in orbital angular momentum to achieve secure communication exceeding traditional limits.

Contribution

It introduces the first experimental realization of HDQKD with a colloidal quantum dot source at room temperature, enabling secure qudit transmission with high efficiency.

Findings

Secure qudit transmission exceeding one bit per photon

Feasibility of using colloidal quantum dots as practical single-photon sources for HDQKD

Demonstration of high-dimensional encoding in orbital angular momentum

Abstract

High-dimensional quantum key distribution (HDQKD) is a promising avenue to address the inherent limitations of basic QKD protocols. However, experimental realizations of HDQKD to date have relied on indeterministic photon sources that limit the achievable key rate. In this paper, we demonstrate a full emulation of a HDQKD system using a single colloidal giant quantum dot (gQD) as a deterministic, compact and room-temperature single-photon source (SPS). We demonstrate a practical protocol by encoding information in a high-dimensional space ($d = 3$) of the orbital angular momentum of the photons. Our experimental configuration incorporates two spatial light modulators for encoding and decoding the spatial information carried by individual photons. Our experimental demonstration establishes the feasibility of utilizing high radiative quantum yield gQDs as practical SPSs for HDQKD. We also demonstrate experimentally secure qudit transmission exceeding one secure bit per photon, thus already beating the traditional d=2 QKD capacity.