Federico Grasselli - Quantum Cryptography: From Key Distribution to Conference Key Agreement

The book series Quantum Science and Technology is dedicated to one of today's most active and rapidly expanding fields of research and development. In particular, the series will be a showcase for the growing number of experimental implementations and practical applications of quantum systems. These will include, but are not restricted to: quantum information processing, quantum computing, and quantum simulation; quantum communication and quantum cryptography; entanglement and other quantum resources; quantum interfaces and hybrid quantum systems; quantum memories and quantum repeaters; measurement-based quantum control and quantum feedback; quantum nanomechanics, quantum optomechanics and quantum transducers; quantum sensing and quantum metrology; as well as quantum effects in biology. Last but not least, the series will include books on the theoretical and mathematical questions relevant to designing and understanding these systems and devices, as well as foundational issues concerning the quantum phenomena themselves. Written and edited by leading experts, the treatments will be designed for graduate students and other researchers already working in, or intending to enter the field of quantum science and technology.

More information about this series at http://www.springer.com/series/10039

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Stimulated by concerns about the secrecy of our data and their secure transmission, there is worldwide active research on quantum cryptography and particularly on Quantum Key Distribution (QKD).

QKD allows two users to communicate with a higher level of security thanks to the laws of quantum physics, making it a candidate to replace current cryptographic schemes. This attracted the attention of governments, institutions and companies to invest in quantum cryptographic technologies, as confirmed by regular theoretical breakthroughs and record-breaking experiments.

This book intends to introduce the reader to QKD and its recent multiparty generalization, called (quantum) Conference Key Agreement (CKA).

While providing a comprehensive view of the state of the art of the field, the book also offers a didactic guidance towards the latest developments, allowing non-expert readers to eventually participate in the on-going research. This is eased by explaining new ideas in an intuitive way and by going into the details of fundamental concepts.

I believe that the growing attention being received by QKD, combined with the novel introduction to CKA, makes this book a timely publication.

I wish the reader an enjoyable read and I hope it can inspire further progress on the flourishing field of quantum cryptography.

Without the knowledge and expertise developed during my doctoral studies, as well as the advancements we contributed to, this book would probably not have been possible. For this, I must thank my Ph.D. supervisor Dagmar Bru and my co-supervisor Hermann Kampermann for giving me the opportunity to join them at the Institute for Theoretical Physics III in Heinrich-Heine-Universitt Dsseldorf. My research greatly benefited from the guidance provided by Dagmar and Hermann, from their constructive criticisms and their passionate attitude towards science. They will certainly represent an inspiration for me throughout my career.

I also would like to thank my other colleagues in Dsseldorf. In particular, I acknowledge the fruitful collaborations with Glucia Murta and the help of Carlo Liorni, Giulio Gianfelici, Lucas Tendick, Sarnava Datta and Thomas Wagner who proofread some chapters of this book.

I am grateful for the opportunities to collaborate with other great scientists, who enriched and widened my view on many research topics. Among these, I am particularly thankful to Marcos Curty and lvaro Navarrete in Vigo and Massimiliano Proietti, Joseph Ho and Alessandro Fedrizzi in Edinburgh.

Moving from Italy to Germany and starting a new social life was made much easier thanks to the amazing group of international friends I had the fortune to meet in these years. A special thanks goes to Ayesha Din for her love, unconditional support and for being my biggest fan.

The greatest merit for shaping the person I am and enabling me to achieve such goals goes to my parents. The value of the education I received from them becomes cleareras for many of uswhen older. Here I acknowledge all of that value and express my deepest gratitude.