Storing quantum dynamics in quantum states: stochastic programmable gate for U(1) operations

Abstract

We show how quantum dynamics can be captured in the state of a quantum system, in such a way that the system can be used to stochastically perform, at a later time, the stored transformation perfectly on some other quantum system. Thus programmable quantum gates for quantum information processing are feasible if some probability of failure -that we show to decrease exponentially with the size of the storing resources- is allowed.

RevTex, 4 pages, 3 figures. Extension of quant-ph/0012067, including several results concerning optimality of the scheme for storage of operations