  As we know, "Who can be said to be a conscious being?" is one of the hard
problems in present science, and no method has been found to strictly
differentiate the conscious being from the being without consciousness or usual
matter. In this short paper, we present a strict physical method based on
revised quantum dynamics to test the existence of consciousness, and the
principle is to use the distinguishability of nonorthogonal single states. We
demonstrate that although the dynamical collapse time can't be measured by a
physical measuring device, a conscious being can perceive it under the assumed
QSC condition, thus can distinguish the nonorthogonal single states in the
framework of revised quantum dynamics This in principle provides a quantum
method to differentiate man and machine, or to test the existence of
consciousness. We further discuss the rationality of the assumed QSC condition,
and denote that some experimental evidences have indicated that our human being
can satisfy the condition. This not only provides some confirmation of our
method, but also indicates that the method is a practical proposal, which can
be implemented in the near future experiments.
