Generador de números aleatorios cuánticos para aplicaciones industriales

Carlos Abellán Sánchez

Valerio Pruneri

Randomness is one of the most intriguing, inspiring and debated topics throughout history. It is a concept that arises when we ask ourselves about our own existence: Why are we the way we are? Do we have free will? Is evolution the result of chance? And at the same time, when we try to understand our relationship with the universe itself. Why are we here? When or how did it all begin? Is the universe a deterministic machine or is there room for chance? Surprisingly, randomness also plays a crucial role in the information and technology era. Random numbers are used in communication protocols such as Ethernet, in classification and processing algorithms such as Page Rank. It is also used in Monte Carlo methods, within the fields of physics, biology, chemistry, finance or mathematics. But the most iconic application for random numbers is found in the field of cryptography or cybersecurity where random numbers generate cryptographic keys, the basic element that provides the security and privacy of our communications. The thesis starts from the following fundamental question: Does randomness exist in photonics? If so, how can we extract it and make it accessible to everyone? To address these two questions, tools from fundamental physics to engineering have been combined. The thesis starts from a detailed study of the phase diffusion process in semiconductor lasers and how to apply this process to the generation of random numbers. Unlike other physical processes based on deterministic laws of nature, phase diffusion has a purely quantum origin, and therefore, is an ideal source for generating random numbers. First, and using this phase diffusion process, we created the fastest quantum random number generator ever implemented (at that time) using only components from the telecommunications industry. More than 40 Gb/s were demonstrated using a pulsed laser scheme. Subsequently, we built several prototypes that were tested in fundamental science and supercomputing applications. In particular, some of the prototypes developed in this thesis were key in the famous loophole-free Bell tests experiments performed in 2015. In the process of building these prototypes, we started a new line of research to try to answer a new question: How do we know if the random numbers we generate really arise from the phase diffusion process? As a result, we introduced a new methodology, randomness metrology. Finally, we moved in the direction of miniaturization of the technology using techniques from the integrated photonics industry. In particular, we demonstrated the first fully integrated quantum random number generator, using a two-laser scheme on an Indium Phosphide chip. In parallel, we also demonstrated the integration of part of the device using Silicon technology, thus opening the door to large-scale production through the most advanced semiconductor industry.

En una sociedad dominada por las tecnologías de la información y la comunicación, garantizar la seguridad de los datos es fundamental. Desde el intercambio de mensajes con nuestros amigos hasta la posibilidad de que empresas y gobiernos compartan datos sensibles, la seguridad también es crucial en el desarrollo de la sociedad hiperconectada. En este nuevo paradigma tecnológico, miles de millones de dispositivos del Internet de las Cosas se conectarán a Internet, junto con dispositivos wearables y sistemas de atención médica personalizados. Los vehículos autónomos nos llevarán a todas partes, y la Industria 4.0 y las tecnologías blockchain transformarán las empresas y las operaciones en todo el mundo. Sin embargo, sin garantías de seguridad efectivas y a largo plazo, la mayoría de estas nuevas tecnologías nunca llegarán al mercado. Las tecnologías actuales de ciberseguridad se basan en supuestos computacionales no probados, lo que compromete la privacidad de nuestras comunicaciones. Las consecuencias de tener todos nuestros datos expuestos son inmensurables, y urge desarrollar nuevas soluciones a largo plazo. Cabe destacar que las tecnologías cuánticas ofrecen oportunidades únicas para este propósito. Las fuentes de entropía cuántica y los sistemas de distribución de claves cuánticas pueden resolver dos de los requisitos más básicos de la criptografía: la generación de claves impredecibles y su distribución. En esta tesis, hemos desarrollado y demostrado una fuente de entropía cuántica altamente escalable con el potencial de integrarse en cualquier dispositivo conectado, lo que, en última instancia, proporciona garantías de seguridad sin precedentes en cualquier dispositivo. Esta misma tecnología para asegurar las comunicaciones también puede emplearse en algoritmos aleatorios, que se emplean para resolver problemas complejos, como los métodos de Monte Carlo para finanzas, ciencia o ingeniería, y el aprendizaje automático para la inteligencia artificial.

Randomness; Existence; Free Will; Evolution; Chance; Universe; Deterministic Machine; Information and Technology Era; Random Numbers; Communication Protocols; Ethernet; Classification Algorithms; Processing Algorithms; Page Rank; Monte Carlo Methods; Physics; Biology; Chemistry; Finance; Mathematics; Cryptography; Cybersecurity; Cryptographic Keys; Security; Privacy; Photonics; Phase Diffusion Process; Semiconductor Lasers; Quantum Origin; Quantum Random Number Generator; Telecommunications Industry; Pulsed Laser Scheme; Prototypes; Fundamental Science; Supercomputing Applications; Loophole-free Bell Tests; Randomness Metrology; Miniaturization; Integrated Photonics Industry; Fully Integrated Quantum Random Number Generator; Two-Laser Scheme; Indium Phosphide Chip; Silicon Technology; Large-Scale Production; Semiconductor Industry.