  We show how quantum dynamics (a unitary transformation) can be captured in
the state of a quantum system, in such a way that the system can be used to
perform, at a later time, the stored transformation almost perfectly on some
other quantum system. Thus programmable quantum gates for quantum information
processing are feasible if some small degree of imperfection is allowed. We
discuss the possibility of using this fact for securely computing a secret
function on a public quantum computer. Finally, our scheme for storage of
operations also allows for a new form of quantum remote control.
