Effect of noise and topologies on multi-photon quantum protocols

TL;DR

This work addresses the practicality of Kak's three-stage QKD protocol in noisy, multi-photon regimes for quantum-augmented networks. It combines a network-simulation framework with multiple noise models and topology configurations (direct, grid, torus, ring) to quantify how multi-photon bursts affect security and transmission metrics. The results show that multi-photon implementations can mitigate noise, achieving substantial per-bit success rates, with ring and torus topologies providing notable robustness, while attenuation limits performance over longer links. The findings offer guidance on repeater placement and topology choice for building scalable quantum-augmented networks under realistic hardware constraints.

Abstract

Quantum-augmented networks aim to use quantum phenomena to improve detection and protection against malicious actors in a classical communication network. This may include multiplexing quantum signals into classical fiber optical channels and incorporating purely quantum links alongside classical links in the network. In such hybrid networks, quantum protocols based on single photons become a bottleneck for transmission distances and data speeds, thereby reducing entire network performance. Furthermore, many of the security assumptions of the single-photon protocols do not hold up in practice because of the impossibility of manufacturing single-photon emitters. Multi-photon quantum protocols, on the other hand, are designed to operate under practical assumptions and do not require single photon emitters. As a result, they provide higher levels of security guarantees and longer transmission distances. However, the effect of channel and device noise on multiphoton protocols in terms of security, transmission distances, and bit rates has not been investigated. In this paper, we focus on channel noise and present our observations on the effect of various types of noise on multi-photon protocols. We also investigate the effect of topologies such as ring, star, and torus on the noise characteristics of the multi-photon protocols. Our results show the possible advantages of switching to multi-photon protocols and give insights into the repeater placement and topology choice for quantum-augmented networks.

Figures (9)

• Figure 1: Depicting the random-rotational noise model on a unit circle. parakh2016correcting
• Figure 2: Demonstration of the effect of dephasing noise model on a qubit through Bloch sphere representation. The phase change is completely arbitrary, and this figure just serves as one of the examples of such a dephasing error in a system.
• Figure 3: Demonstration of the effect of Bit-flip noise model on a qubit through Bloch-sphere representation.
• Figure 4: Different topologies used in our QKD simulations.
• Figure 5: Relationship between multi-photon burst size and $\%$ of successful qubits per bit over different topologies.