Julien Bernu
Laboratoire Kastler Brossel, Ecole Normale Supérieure
Note different date and time
Monday, January 28, 2008
3:00 pm in SPL 52
QND measurement of light: observing the quantum Zeno effect and watching the decoherence
Abstract: Thanks to a very high finesse superconducting microwave cavity [1] we have been able to implement a non destructive (QND) measurement of the photon number of an electromagnetic field and record for the first time its quantum jumps [2]. This method was also an efficient tool to test all the quantum measurement postulates [3]. I will show that we can use this QND measurement to observe the quantum Zeno effect: a coherent evolution of the field can be frozen by a continuous measurement ("A watched kettle never boils!"). Finally this measurement is a powerful source of highly non-classical states like large n Fock states and Schrödinger cat states and opens wide perspectives to the study of decoherence.
[1] S. Kuhr et al., Appl. Phys. Lett. 90, 164101 (2007)
[2] S. Gleyzes et al., Nature 446, 297-300 (2007)
[3] C. Guerlin et al., Nature 448, 889-893 (2007)