  A candidate for converting quantum information from microwave to optical
frequencies is the use of a single atom that interacts with a superconducting
microwave resonator on one hand and an optical cavity on the other. The large
electric dipole moments and microwave transition frequencies possessed by
Rydberg states allow them to couple strongly to superconducting devices. Lasers
can then be used to connect a Rydberg transition to an optical transition to
realize the conversion. Since the fundamental source of noise in this process
is spontaneous emission from the atomic levels, the resulting control problem
involves choosing the pulse shapes of the driving lasers so as to maximize the
transfer rate while minimizing this loss. Here we consider the concrete example
of a cesium atom, along with two specific choices for the levels to be used in
the conversion cycle. Under the assumption that spontaneous emission is the
only significant source of errors, we use numerical optimization to determine
the likely rates for reliable quantum communication that could be achieved with
this device. These rates are on the order of a few Mega-qubits per second.
