Quantum random number generators in integrated photonics

  • Francesco Raffaelli

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)

Abstract

Random numbers find applications in a range of different fields, from quantum key distribution and classical cryptography to fundamental science. They also find extensive use in gambling and lotteries. By exploiting the probabilistic nature of Quantum Mechanics, quantum random number generators (QRNGs) provide a secure and efficient means to produce random numbers. Most of the quantum random
number generators demonstrated so far have been built in bulk optics, either using free space or fibre-optic components. While showing good performance, most of these demonstrations are strongly limited in real life applications, due to issues such as size, costs and the manufacturing process.
In this thesis I report the demonstration of three different QRNGs based on integrated photonics. First, I demonstrated a QRNG based on homodyne measurement
of optical vacuum states on a Silicon-on-insulator (SOI) chip. Second, I developed a SOI QRNG based on phase fluctuations from a laser diode. In these two schemes all the optical and opto-electronic components, excluding the laser, were integrated onto a silicon-on-insulator device. These schemes, being built on a silicon-on-insulator chip are potentially CMOS compatible and pave the way for being integrated onto other more complex systems. These QRNGs showed Gbps generation rates and passed the statistical tests provided by NIST. Third, I report the preliminary study of a QRNG based on homodyne measurement of optical vacuum states onto a Indium Phosphide (InP) chip. In this third experiment, all the components, including a laser diode, were monolithically integrated in the same chip, which provide a great
advantage in terms of the overall size of the optics of the device.
Date of Award23 Jan 2019
Original languageEnglish
Awarding Institution
  • The University of Bristol
SupervisorJonathan C F Matthews (Supervisor) & Dylan Mahler (Supervisor)

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