Semiconductor lasers in quantum cryptography
File(s)
Author(s)
Lovic, Victor
Type
Thesis
Abstract
The unique properties of quantum mechanics, like entanglement and superposition, can be leveraged to carry out cryptographic tasks that cannot be achieved by classical means. For example, Quantum Key Distribution (QKD) enables two parties to communicate in a provably secure manner. Another application is Quantum Random Number Generation (QRNG), exploiting the inherent randomness in quantum mechanics to generate truly random numbers.
Semiconductor lasers are a key technology in both QKD and QRNG and greatly influence the performance and security of these systems. Semiconductor lasers are also an advanced technology, benefitting from decades of research and development from the field of classical fibre optic communications. This has resulted not only in low-cost, high-performance devices, but also an extensive associated literature.
While QKD and QRNG have similar laser requirements to classical fibre optic communications, and have thus significantly benefitted from the associated research and development, they also have unique requirements and use cases that have been insufficiently explored by the current literature. This thesis draws from the existing literature to study semiconductor lasers specifically in the context of quantum cryptography.
We introduce the essential methods for modelling semiconductor lasers and provide two specific applications of them. In the first, we model phase noise in a gain-switched laser diode, crucial for security in quantum cryptography. And second, we study the so-called laser seeding attack in QKD. Throughout our work we complement our simulation results with experiments, and vice versa. This thesis contributes to the security and performance of QKD and QRNG, and provides tools and techniques for further study of semiconductor lasers in quantum cryptography.
Semiconductor lasers are a key technology in both QKD and QRNG and greatly influence the performance and security of these systems. Semiconductor lasers are also an advanced technology, benefitting from decades of research and development from the field of classical fibre optic communications. This has resulted not only in low-cost, high-performance devices, but also an extensive associated literature.
While QKD and QRNG have similar laser requirements to classical fibre optic communications, and have thus significantly benefitted from the associated research and development, they also have unique requirements and use cases that have been insufficiently explored by the current literature. This thesis draws from the existing literature to study semiconductor lasers specifically in the context of quantum cryptography.
We introduce the essential methods for modelling semiconductor lasers and provide two specific applications of them. In the first, we model phase noise in a gain-switched laser diode, crucial for security in quantum cryptography. And second, we study the so-called laser seeding attack in QKD. Throughout our work we complement our simulation results with experiments, and vice versa. This thesis contributes to the security and performance of QKD and QRNG, and provides tools and techniques for further study of semiconductor lasers in quantum cryptography.
Version
Open Access
Date Issued
2023-09
Date Awarded
2024-03
Copyright Statement
Creative Commons Attribution NonCommercial Licence
License URL
Advisor
Kim, Myungshik
Shields, Andrew
Sponsor
Engineering and Physical Sciences Research Council
Grant Number
EP/S513635/1
Publisher Department
Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)