Observation of query pulse length dependent Ramsey interference in rubidium vapor using pulsed Raman excitation

We report observation of query pulse length dependent Ramsey interference (QPLD-RI), using pulsed Raman excitation in rubidium vapor. This is observed when a long, attenuated query pulse is used during pulsed Raman excitation. We explain the physical mechanism behind the QPLD-RI using a Bloch vector model. We also use numerical solutions to time-dependent density matrix equations to simulate this interference effect, showing qualitative agreement with experimental results. Presence of such interference could create a potential source of error in a vapor cell Raman clock constructed using frequency-domain Ramsey interference (FDRI).