Quantum computers and dissipation

Abstract

We analyse dissipation in quantum computation and its destructive impact on\nefficiency of quantum algorithms. Using a general model of decoherence, we\nstudy the time evolution of a quantum register of arbitrary length coupled with\nan environment of arbitrary coherence length. We discuss relations between\ndecoherence and computational complexity and show that the quantum\nfactorization algorithm must be modified in order to be regarded as efficient\nand realistic.\n