  The coherent control of mesoscopic ensembles of atoms and Rydberg atom
blockade are the basis for proposed quantum devices such as integrable gates
and single photon sources. So far, experimental progress has been limited to
complex experimental setups that use ultracold atoms. Here, we show that
coherence times of ~100ns are achievable with coherent Rydberg atom
spectroscopy in um sized thermal vapor cells. We investigated states with
principle quantum numbers between 30 and 50. Our results demonstrate that
microcells with a size on the order of the blockade radius, ~2um, at
temperatures of 100-300C are robust, promising candidates to investigate low
dimensional strongly interacting Rydberg gases, construct quantum gates and
build single photon sources.
