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

Michel Brune (1) , Julien Bernu (1) , Christine Guerlin (1) , Samuel Deléglise (1) , Clément Sayrin (1) , Sébastien Gleyzes (1) , Stefan Kuhr (2) , Igor Dotsenko (1, 3) , Jean-Michel Raimond (1) , Serge Haroche (1, 3)

1 LKB (Lhomond) - Laboratoire Kastler Brossel
2 Institut für Physik Johannes Gutenberg Universität
3 LKB [Collège de France] - Laboratoire Kastler Brossel

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. The damping rates of the $n$ photon states ($0\leq n \leq 7$) are found to increase linearly with $n$. The results are in excellent agreement with theory including a small thermal contribution.

Mots clés: quantum measurement QND fock state lifetime

Domaines: Physique Quantique [quant-ph]

Michel Brune, Julien Bernu, Christine Guerlin, Samuel Deléglise, Clément Sayrin, et al.. Process tomography of field damping and measurement of Fock state lifetimes by quantum non-demolition photon counting in a cavity. Physical Review Letters, 2008, 101 (24), pp.240402. ⟨10.1103/PhysRevLett.101.240402⟩. ⟨hal-00319638⟩