The twenty-first century is seeing the emergence of the first truly quantum technologies; that is, technologies that rely on the counter-intuitive properties of individual quantum systems and can often outperform any conventional technology. Examples include quantum computing, which promises to be much faster than conventional computing for certain problems, and quantum metrology, which promises much more sensitive parameter estimation than that offered by conventional techniques. To realize these promises, it is necessary to understand the measurement and control of quantum systems. This book serves as an introduction to quantum measurement and control, including some of the latest developments in both theory and experiment.

Scope and aims

To begin, we should make clear that the title of this book is best taken as short-hand for ‘Quantum measurements with applications, principally to quantum control’. That is, the reader should be aware that (i) a considerable part of the book concerns quantum measurement theory, and applications other than quantum control; and (ii) the sort of quantum control with which we are concerned is that in which measurement plays an essential role, namely feedback (or feedforward) control of quantum systems.

Even with this somewhat restricted scope, our book cannot hope to be comprehensive. We aim to teach the reader the fundamental theory in quantum measurement and control, and to delve more deeply into some particular topics, in both theory and experiment.