Toward multi-purpose quantum communication networks: from theory to protocol implementation

TL;DR

By establishing a methodology to evaluate the performance and security of quantum communication protocols, this work takes a significant step towards industrializing and deploying large-scale, multi-purpose quantum communication networks.

Abstract

Most quantum communication networks around the world are used for a single task: quantum key distribution. In order to initiate the transition to multi-purpose quantum communication networks, we demonstrate the implementation of two different tasks on the same quantum key distribution hardware. Specifically, we focus on quantum oblivious transfer and quantum tokens. Our main contribution is to establish a methodology that greatly simplifies the expertise required to achieve the deployment, assess its performance, and evaluate its feasibility at a large scale. The implementation that we present is full-stack. It is based on a development framework that allows running user-defined applications both with simulated or real quantum communication backend. The hardware used for the implementation is VeriQloud's Qline. The simulation backend reproduces exactly the inputs and outputs of the real hardware, but also its losses and errors. It can therefore be used to validate the implementation before running it on the real hardware. The sources of the software that we use are fully open, making our research reproducible. The security of the implementations on real hardware are discussed with respect to security bounds previously known in the literature. We also discuss the engineering choices that we made in order to make the implementations feasible. By establishing a methodology to evaluate the performance and security of quantum communication protocols, we take a significant step towards industrializing and deploying large-scale, multi-purpose quantum communication networks.

Figures (9)

• Figure 1: The software stack -- the application interacts with gc but remains oblivious of the backend. It can run both on simulated or real quantum hardware.
• Figure 2: Minimum number of qubits to be received by Bob and corresponding time to extract one bit of secure key, using a good code (inefficiency $1.2$), $\epsilon_{\text{sec}}=10^{-10}$, $\epsilon_{\text{cor}}=10^{-10}$. The hardware parameters are those of Qline.
• Figure 3: Estimation of the number of qubits to be received, and corresponding time required on Qline, to perform one OT as a function of the qber. The inefficiency of the error correction is set to $1.25$.
• Figure 4: Time required to generate 1 quantum token depending (a) on the qubit error rate or (b) on the detection efficiency
• Figure 5: OT running on VQ hardware: measured time to obtain one OT on Qline (top subplot) and evolution of the qber over time (bottom subplot). The number of qubits to be received is set to $N\approx 1.26 \times 10^7$.