  We demonstrate the ability to control the spontaneous emission from a
superconducting qubit coupled to a cavity. The time domain profile of the
emitted photon is shaped into a symmetric truncated exponential. The experiment
is enabled by a qubit coupled to a cavity, with a coupling strength that can be
tuned in tens of nanoseconds while maintaining a constant dressed state
emission frequency. Symmetrization of the photonic wave packet will enable use
of photons as flying qubits for transfering the quantum state between atoms in
distant cavities.
