Vapor cell Rydberg atom electrometry with time-separated fields

Rydberg atoms have large transition electric dipole moments and high sensitivity to electric fields. We describe a new method for microwave field sensing in a vapor cell consisting of separate excitation, quantum evolution between two Rydberg levels in the dark and state-dependent detection with probe laser transmission. Using microwave pulse techniques we study homogeneous and inhomogeneous relaxation of the coherence between Rydberg levels and demonstrate detection of a 10 GHz signal with electric field sensitivity of 10 nV/cm/Hz${}^{1\mathrm{/}2}$.