Measuring the photon number parity in a cavity: from light quantum jumps to the tomography of non-classical field states
S. Haroche, M. Brune, J. M. Raimond · Journal of Modern Optics · 2007
The photon number parity is a binary observable playing an important role in the description of the non-classical features of light. In microwave experiments, this observable can be measured by using a single Rydberg atom evolving in a two dimension space and interacting dispersively with a field stored in one or two cavities. The procedure, based on atomic interferometry, maps the field parity (+ 1 or − 1) onto the states of the two-level atom. By performing repeated measurements of the field parity, it is possible to observe field quantum jumps, to reconstruct the complete Wigner function of an arbitrary field and to study how it evolves due to decoherence.