Quantum Reversibility and a New Model of Quantum Automaton

Since a quantum computational system is a generalization of a classical computational system, its computational power should be greater or equal than that of the classical system. In spite of that the computational power of 1-way quantum finite automata has been shown to be smaller than that of their classical counterpart. I argue that this paradox lies on the ground that the currently accepted definition of quantum automaton neglects the concept of quantum reversibility. In this article I review the role that reversibility plays into quantum computing and I propose a new model of 1-way quantum finite automata whose computational power is at least equal to that of classical automata.