This book is based on an in-depth conversation between Howard Burton and Artur Ekert, Professor of Quantum Physics at the Mathematical Institute at the University of Oxford and Director of the Centre for Quantum Technologies and Lee Kong Chian Centennial Professor at the National University of Singapore. Artur Ekert is best known as one of the pioneers of quantum cryptography. This wide-ranging conversation provides detailed insights into his research and covers many fascinating topics such as mathematical and physical intuition, a detailed history of cryptography from antiquity to the present day and how it works in practice, the development of quantum information science, the nature of reality, and more.This carefully-edited book includes an introduction, Putting the Pieces Together, and questions for discussion at the end of each chapter:I. Beginnings - Mathematics, physics and intuitionII. Cryptographic Essentials - From the ancient Greeks to the Cold WarIII. Public Key Cryptosystems - Harnessing the difficulty factorIV. Harnessing Interference - The power of quantum computersV. Quantum Sociology - What is quantum information science, anyway?VI. Quantum Metaphysics - And its concrete effectsVII. The Joy of Questioning - And the merits of being rebelliousAbout Ideas Roadshow Conversations:This book is part of a series of 100 Ideas Roadshow Conversations. Presented in an accessible, conversational format, Ideas Roadshow books not only explore frontline academic research featuring world-leading researchers but also reveal the inspirations and personal journeys behind the research.