  In the study of quantum process algebras, researchers have introduced
different notions of equivalence between quantum processes like bisimulation or
barbed congruence. However, there are intuitively equivalent quantum processes
that these notions do not regard as equivalent. In this paper, we introduce a
notion of equivalence named observational equivalence into qCCS. Since quantum
processes have both probabilistic and nondeterministic transitions, we
introduce schedulers that solve nondeterministic choices and obtain probability
distribution of quantum processes. By definition, the restrictions of
schedulers change observational equivalence. We propose some definitions of
schedulers, and investigate the relation between the restrictions of schedulers
and observational equivalence.
