8 research outputs found
Quantum Pushdown Automata
Quantum finite automata, as well as quantum pushdown automata (QPA) were
first introduced by C. Moore and J. P. Crutchfield. In this paper we introduce
the notion of QPA in a non-equivalent way, including unitarity criteria, by
using the definition of quantum finite automata of Kondacs and Watrous. It is
established that the unitarity criteria of QPA are not equivalent to the
corresponding unitarity criteria of quantum Turing machines. We show that QPA
can recognize every regular language. Finally we present some simple languages
recognized by QPA, not recognizable by deterministic pushdown automata.Comment: Conference SOFSEM 2000, extended version of the pape