%0 Journal Article %T Quantum Computers and Dissipation %A G. Massimo Palma %A Kalle-Antti Suominen %A Artur K. Ekert %J Physics %D 1997 %I arXiv %R 10.1098/rspa.1996.0029 %X We analyse dissipation in quantum computation and its destructive impact on efficiency of quantum algorithms. Using a general model of decoherence, we study the time evolution of a quantum register of arbitrary length coupled with an environment of arbitrary coherence length. We discuss relations between decoherence and computational complexity and show that the quantum factorization algorithm must be modified in order to be regarded as efficient and realistic. %U http://arxiv.org/abs/quant-ph/9702001v1