Quantum One-Sided Exact Error Algorithms

We define a complexity class for randomized algorithms with one-sided error that is exactly equal to a constant (unlike the usual definitions, in which the error is only bounded above or below by a constant). We show that the corresponding quantum classes (one each for a different error probability) are in fact all equivalent to each other and to EQP, the quantum analogue of P. The technique used is a form of quantum amplitude amplification.