Classical simulation complexity of quantum machines

We present a classical probabilistic simulation technique of quantum Turing machines. As a corollary of this technique we obtain several results on relationship among classical and quantum complexity classes such as: PrQP = PP, BQP ⊆ PP and PrQSPACE(S(n)) = PrPSPACE(S(n)). © Springer-Verlag Berlin Heidelberg 2003