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Abstract:

Quantum information theory seeks to unite some of the most influential ideas of 20th century science: quantum mechanics, computer science and information theory. The development of quantum information theory has only begun, and only a few applications are known, mostly in quantum system control and data security. The future of the theory is hard to predict, but it seems poised to contribute to some of the most exciting ideas of the 21st century. This theory gives an ideal framework for developing a better understanding of how nature works and what it will allow to be done.

Abstract:

Quantum entanglement looks like telepathy when three physicists get together on a game show.

Abstract:

We first consider the basic requirements for a quantum computer, arguing for the attractiveness of nuclear spins as information-bearing entities, and light for the coupling which allows quantum gates. We then survey the strengths of and immediate prospects for quantum information processing in ion traps. We discuss decoherence and gate rates in ion traps, comparing methods based on the vibrational motion with a method based on exchange of photons in cavity QED. We then sketch the main features of a quantum computer designed to allow an algorithm needing 106 Toffoli gates on 100 logical qubits. We find that around 200 ion traps linked by optical fibres and high-finesse cavities could perform such an algorithm in a week to a month, using components at or near current levels of technology.

Abstract:

Information is stored, transmitted and processed always by physical means. Thus the concept of information and computation can be properly formulated only in the context of a physical theory and the study of information processing requires experimentation. It is clear that if computers are to become much smaller in the future, their description must be given by quantum mechanics. Somewhat more surprising is the fact that quantum information processing can be qualitatively different and much more powerful than its classical analogue. In the following we will explain why.