Moore, Cristopher; Crutchfield, James P. - Santa Fe Institute - 1997
To study quantum computation, it might be helpful to generalize structures from language and automata theory to the … quantum case. To that end, we propose quantum versions of finite-state and push-down automata, and regular and context … generating functions, and Greibach normal form. We also show that there are quantum context-free languages that are not context-free. …