Quantum Computation and Quantum Information (Cambridge Series on Information and the Natural Sciences)

I'm an undergraduate student in Computer Science, doing my Diploma (BS/MS) thesis on Quantum Computing and Algorithms. If you are computer scientist, mathematician or physicist and you want some startup information, this is the book you are looking for. Although, the book doesn't assume that you have appropriate background on mathematics or computer science, it will be good that you have some affiliation with linear algebra, tensor calculus and basic computational complexity concepts. The book is excellent for self study and research, containing many exercises. Another more mathematical book is Classical and Quantum Computing (AMS) by Kitaev, Shen and Vyalyi. It cannot complement the first book but it will give you precise mathematical approach on computational complexity-classical computing (first 50 pages), which is needed to continue and understand concepts of quantum complexity classes and quantum algorithms.

It is a book for specialists. In order to fully appreciate the contents you should have a physics, maths or computation science diploma. It contains a good introduction on Quantum mechanics, but for people that have already assited an introductory course on the field. Concerning the main subject: quantum computation, this book is the most complete review of the field and also suitable for a course on QC.

I'm a master student in the field of electrical engineering and quantum cryptography gona be my thesis topic. I found this book comprehensive and useful as a book for starters. If you resist the second chapter which is a compressed chapter on linear algebra(it tries to teach you a complete under graduate course on linear algebra in 30 pages!!!) then you'll be pleased with the rest of the book ("I'm in the middle right now").

In fact I read it every day and then I find myself falling asleep. I even use it as a bed time story for my 1.5 years old son. works like magic, the only problem is sometimes I fall asleep before him.

I've recently purchased this book, and have only read the first 50 or so pages. However, it is clear thus far that the authors have invested alot of time in making such a complex topic as clear as possible, with simple examples to express fundamental concepts. I'm looking forward to reading the rest.

There is great excitement currently about quantum computing and its laboratory realization. Recent press releases have indicated successes in implementing quantum computation and this no doubt has encouraged the excitement. The authors of this book have been directly involved in the experimental and theoretical developments behind quantum computing and have written a fair summary of the subject as was known at the time it was first published (2000).The theory behind quantum computing is outlined in some detail in the book, but the experimental situation is not, and this is disappointing since it is the laboratory realization of quantum computing that is most interesting. Most implementations of quantum computing theoretically are dependent on the notion of entanglement of states, and in my opinion there is no convincing experimental evidence of entanglement. Theoretical constructions that employ entanglement have grown considerably in recent years, but the experimental situation is far behind these developments. This book unfortunately does not look critically at the experimental justification for entanglement, but uses concepts of entanglement throughout to lay the groundwork for a theory of quantum computation. Indeed one could say that the entire book rests on the notion of entangled states and being able to manipulate these states via various transformations, called 'entanglement transformations' by the authors.The authors do however devote an entire chapter to the physical realization of quantum computers , although again no real experimental data is given. The role of the decoherence time is emphasized in the discussion, and a chart is given listing rough estimates for decoherence times for various candidate realizations of quantum computers. Several different scenarios for quantum computers are outlined in the chapter, and the discussion gives some credence to the view that the theory of quantum computation has some physical meaning to it, rather than just a theory of computation based on the properties and geometry of Hilbert space. Indeed, one could easily take this later viewpoint, as it is one thing to call a mathematical construction 'quantum' and another to really find a physical (quantum) system that actually behaves in a manner compatible with these constructions. If one is to speak of 'quantum' computation and not just 'Hilbert space' computation, one must show beyond doubt that the system executing the computation is indeed a physical and quantum one. A mere statement that 'physics is computation' is not enough. Indeed, there are a few examples of using Hilbert space properties to enhance the performance of various algorithms. For example, one can speed up the training portion in neural networks by complexifying the weights. In addition, one can employ a tunneling scheme to alleviate the problems of local minima in these networks, and in gradient algorithms in general. These approaches all take advantage of Hilbert space geometry and the ability to do superposition of states, but none of them correspond at all to physical systems, let alone quantum ones. They are merely mathematical tools used to speed up (dramatically in some cases) a particular algorithm.There has also been a great deal of very exciting research in the employment of the 'quantum' point of view in pure mathematics. New methodologies have been developed for handling difficult mathematical results using such a viewpoint and these have resulted in brilliant developments, especially in differential topology and algebraic geometry. The chapter on distance measures for quantum information in this book could be viewed as part of these developments and strategies. The definition of the fidelity between two quantum states is purely a mathematical convenience that is used (albeit productively) to derive quantities that behave as one would want them to (viewing from a classical standpoint). No physical relevance is given for this metric in the chapter, although it is interesting from a mathematical standpoint. The authors are honest to admit this though, for they state that notions of quantum information are in a state of infancy and no solid (physical) definitions have been given as of yet.If more time were spent on the analysis of the raw experimental data behind the efforts to build quantum computers, and less on purely theoretical considerations, this book would have been a lot more helpful. The literature is bursting with papers on entanglement and its relation to quantum computing and quantum information, but unfortunately, not enough critical analysis of the experimental situation. This book is no different in this regard, but the authors are still enthusiastic about the prospects for quantum computing, difficult as they are. One can only hope that their efforts are successful, that such machines will be built soon, as the consequences are awesome.

The book is good and gives you a general view of quantum information and computation. However, the size of the book disencourages beginners to read it.

I have got the book in good condition but I am not very happy with the delivery system. In my opinion it's a bit long time taking if you are not going for rapid delivery which is very expensive. I have opted for medium delivery time, which in my opinion should be little more faster. So, I would like to ask Amazon to take care little bit about faster delivery to International shipments.Thank you,Ritayan RoyCenter for Quantum Technologies,National University of Singapore,SINGAPORE 117543