Freezing a Coherent Field Growth in a Cavity by Quantum Zeno Effect

Julien Bernu (1) , Samuel Deléglise (1) , Clément Sayrin (1) , Stefan Kuhr (2) , Igor Dotsenko (1, 3) , Michel Brune (1) , 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

We have frozen the coherent evolution of a field in a cavity by repeated measurements of its photon number. We use circular Rydberg atoms dispersively coupled to the cavity mode for an absorption-free photon counting. These measurements inhibit the growth of a Field injected in the cavity by a classical source. This manifestation of the Quantum Zeno effect illustrates the back action of the photon number determination onto the Field phase. The residual growth of the Field can be seen as a random walk of its amplitude in the two-dimensional phase space. This experiment sheds light onto the measurement process and opens perspectives for active quantum feedback.

Mots clés: Quantum; Zeno; QND; Measurement

Domaines: Physique Quantique [quant-ph]

Julien Bernu, Samuel Deléglise, Clément Sayrin, Stefan Kuhr, Igor Dotsenko, et al.. Freezing a Coherent Field Growth in a Cavity by Quantum Zeno Effect. Physical Review Letters, 2008, 101 (18), pp.180402. ⟨10.1103/PhysRevLett.101.180402⟩. ⟨hal-00324515⟩