The Quantum Internet: The Second Quantum Revolution

Book Preface

Quantum technologies are not just of interest to quantum physicists but will have transformative effects across countless areas – the next technological revolution. For this reason, this work is directed at a general audience of not only preexisting quantum computer scientists but also classical computer scientists, physicists, economists, artists, musicians, and computer, software and network engineers. More broadly, we hope that this work will be of interest to those who recognise the future significance of quantum technologies and the implications (or even just curiosities) that globally networking them might have – the creation of the global quantum internet [182, 99]. We expect that the answer to that question will look very different to what emerged from the classical internet.

A basic understanding of quantum mechanics [157], quantum optics [73], quan-tum computing and quantum information theory [127],1 classical networking [177] and computer algorithms [48] are helpful, but not essential, to following our discus-sion. Some mathematical sections require a basic understanding of the mathemat-ical notation of quantum mechanics, although the reader without this background ought to be able to nonetheless follow the broader arguments.

The entirely technically disinterested or mathematically incompetent reader may refer to just Parts I, IX and X – essentially brief, nontechnical, highly speculative essays about the motivation, applications and implications of the future quantum internet.

This work is partially a review of existing knowledge relevant to quantum net-working and partially original ideas, to a large extent based on the adaptation of classical networking concepts and quantum information theory to the context of quantum networking. A reader with an existing background in these areas could skip the respective review sections.

Our goal is to present a broadly accessible technical and nontechnical overview of how we foresee quantum technologies to operate in the era of quantum glob-alisation and the exciting possibilities and emergent phenomena that will evolve from it.

We do not shy away from making bold predictions about the future of the quantum internet, how it will manifest itself and what its implications will be for humanity and for science. Inevitably, some of our predictions will turn out to be accurate, whereas others will completely miss the mark entirely. We have no fear of controversy. How accurate our vision will be will have to be seen, but the most important goal in presenting grandiose predictions is to inspire new research directions, encourage future work and stimulate lively and rigorous scientific debate about future technology. If we succeed at achieving these things, yet every last one of our predictions turn out to be completely and utterly wrong, we will consider this work a resounding success. Our goal, first and foremost, is to inspire future science.

Acknowledgements

The desire to share and unite remote digital assets motivated the development of the classical internet, the enabler of the entire twenty-first century economy and our modern way of life. As we enter the quantum era, it is to be expected that there will be a similar demand for networking quantum assets, motivating a global quantum internet for bringing together the world’s quantum resources, leveraging off their exponential trajectory in capability. We present models for quantum networking, how they might be applied in the future and the implications they will have.

Like the classical internet, it is to be expected that the implications of the quan-tum internet will be far more than technological, with far-reaching economic, polit-ical and geostrategic consequences, which to a large extent act as the driving force for how they will evolve. Although it is impossible to make concrete predictions for the future, we present our treatment of the topic holistically, discussing the interplay between the technology and its driving forces. This includes economic and strategic game-theoretic models that are unique to these quantum technologies, with no direct analogue in terms of conventional analyses. In short, the nonlinear scaling in the utility of quantum resources requires nonlinear economic and strate-gic models. The nonlinear nature in the utility of future quantum infrastructure implies ‘quantum enhancement’ not only from a physical perspective but in terms of their implications for humanity.

This work is based on the combined efforts of a highly interdisciplinary team. Zixin Huang contributed to multiple sections of the book, in particular to those on cryptography and quantum algorithms. He-Liang Huang and Zu-En Su contributed to the sections on experimental quantum optics, the Chinese quantum satellite developments and the early structure of the book. Simon Devitt contributed the sections on the quantum SneakerNet, error correction and fault tolerance. Rohit Ramakrishnan and Chandrashekar Radhakrishnan contributed to the sections on optical interfacing and switching, quantum memories and experimental quantum optics. Si-Hui Tan and Atul Mantri contributed to the sections on secure cloud quantum computing. Nana Liu contributed on quantum machine learning and quan-tum algorithms. Scott Harrison contributed to the sections on economics and game theory. Tim Byrnes contributed the sections on clock synchronisation and tele-scopy. William J. Munro contributed the sections on quantum repeater networks and provided editorial assistance. Jonathan P. Dowling acted as co-editor, although his recent passing implies that a number of differences in editorial opinion now swing in Peter Rohde’s favour, who acted as lead author and editor.