Push down automata vs quantum push down automata

An automaton is a simple model of computer. There are various automata each with its formal definition. Generally an automaton has some form of input, some form of output, internal states may or may not have some form of storage, hardwired not programmable. In this paper we have discussed about Pushdown Automata, Quantum Pushdown Automata by taking some interesting examples. Then the classical Pushdown Automata are compared with Quantum pushdown automata. Our main objective is to know and understand the language recognized by Quantum pushdown automata.