  In the past few years it has been shown that universal quantum computation
can be obtained by projective measurements alone, with no need for unitary
gates. This suggests that the underlying logic of quantum computing may be an
algebra of sequences of quantum measurements rather than an algebra of products
of unitary operators. Such a Sequential Quantum Logic (SQL) was developed in
the late 70's and has more recently been applied to the consistent histories
framework of quantum mechanics as a possible route to the theory of quantum
gravity. In this letter, I give a method for deciding the truth of a
proposition in SQL with nonzero probability of success on a quantum computer.
