Learn More
1 What the book is about This book provides a thorough introduction to quantum information theory and quantum computation in general, especially covering the theoretical and computational , rather than experimental, aspects of these fields. The particular strengths of the volume are: the completeness of both basic and more advanced aspects of quantum(More)
— We show the equivalence of two different notions of quantum channel capacity: that which uses the en-tanglement fidelity as its criterion for success in transmission , and that which uses the minimum fidelity of pure states in a subspace of the input Hilbert space as its criterion. As a corollary, any source with entropy less than the capacity may be(More)
We introduce a model of computation based on read only memory (ROM), which allows us to compare the space-efficiency of reversible, error-free classical computation with reversible, error-free quantum computation. We show that a ROM-based quantum computer with one writable qubit is universal, whilst two writable bits are required for a universal classical(More)
Quantum computers hold great promise for solving interesting computational problems, but it remains a challenge to find efficient quantum circuits that can perform these complicated tasks. Here we show that finding optimal quantum circuits is essentially equivalent to finding the shortest path between two points in a certain curved geometry. By recasting(More)