Professor Artur Ekert FRS

Abstract:

We describe how physics of computation determines computational complexity. In particular we show how quantum phenomena lead to qualitatively new modes of computation. An ideal quantum computer would allow to face certain tasks out of reach of classical computers, the factorization problem being the most striking example. Experimentally, however, implementation of quantum computation faces some serious difficulties due to an interaction with the environment which causes decoherence. We mention quantum error-correction as a process which can, to some extent, protect quantum computers from unwelcome effects of dissipation and decoherence. This is a brief, introductory review of quantum computation. It is based on [1].

Abstract:

Current technology is beginning to allow us to manipulate rather than just observe individual quantum phenomena. This opens up the possibility of exploiting quantum effects to perform computations beyond the scope of any classical computer. Recently Peter Shor discovered an efficient algorithm for factoring whole numbers, which uses characteristically quantum effects. The algorithm illustrates the potential power of quantum computation, as there is no known efficient classical method for solving this problem. The authors give an exposition of Shor's algorithm together with an introduction to quantum computation and complexity theory. They discuss experiments that may contribute to its practical implementation.