Process tomography of field damping and measurement of Fock state lifetimes by quantum non-demolition photon counting in a cavity

Understand

The relaxation of a quantum field stored in a high-$Q$ superconducting cavity is monitored by non-resonant Rydberg atoms.

• The field, subjected to repetitive quantum non-demolition (QND) photon counting, undergoes jumps between photon number states.
• We select ensembles of field realizations evolving from a given Fock state and reconstruct the subsequent evolution of their photon number distributions.
• We realize in this way a tomography of the photon number relaxation process yielding all the jump rates between Fock states.