  Quantum measurement is universal for quantum computation. This universality
allows alternative schemes to the traditional three-step organisation of
quantum computation: initial state preparation, unitary transformation,
measurement. In order to formalize these other forms of computation, while
pointing out the role and the necessity of classical control in
measurement-based computation, and for establishing a new upper bound of the
minimal resources needed to quantum universality, a formal model is introduced
by means of Measurement-based Quantum Turing Machines.
