2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/93887Foundations of the notion of quantum Turing machines are investigated. According to Deutsch's formulation, the time evolution of a quantum Turing machine is to be determined by the local transition function. In this paper, the local transition functions are characterized for fully general quantum Turing machines, including multi-tape quantum Turing machines, extending the results due to Bernstein and Vazirani.22 pages, LaTeX, revised and extended, to appear in RAIRO Theor. Inform. ApplQuantum Physicstext