Motion-induced signal revival in pulsed Rydberg four-wave mixing beyond the frozen gas limit

We present measurements on pulsed four-wave mixing involving a Rydberg state in an atomic vapor cell. The excitation to the Rydberg state is conducted by a pulsed two-photon excitation on the nanosecond timescale that is combined with a third CW laser in phase-matched geometry yielding light emission on the same timescale. An additional signal peak is observed shortly after the pulse that can be attributed to a revival of constructive interference between different velocity classes of the radiating atomic dipoles. Furthermore we investigate the density dependence of the four-wave mixing signal. From the shape of the respective curve we are able to confirm energy and momentum conservation in the photonic part of the system.