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Atomes et Cavité : Complémentarité et Fonctions de Wigner

Abstract : The complementarity principle is a basic concept of quantum
mechanics. It predicts that, in an interferometry experiment, any attempt to
determine which path the particle chose between the two beamsplitters unavoidably
washes out the fringe pattern. In this work, we present an experiment illustrating
this principle in a Ramsey interferometer. One applies two microwave pulses to
circular Rydberg atoms, resonant with an atomic transition, which act like energy
beamsplitters. The probability to detect the atom in a given energy level exhibits
interference fringes. In our experiment, one of the two pulses is applied in the
mode of a superconducting cavity. Thanks to the strong coupling between the atoms
and the cavity, we were able to apply the pulse even when the field in the cavity
contains a small average number of photons (N<1, quantum pulse). The
fringes'contrast is then strongly reduced because the cavity field measures the
atomic state inside the interferometer. This measurement becomes less and less
efficient when N increases. Thus, the fringes'contrast increases also, until it
reaches the intrinsic contrast of a classical Ramsey interferometer when N>>1. A
simple model, based on entanglement between the atom and the cavity, accounts
quantitatively for the measurements made. One of the major interests of the Cavity
Quantum Electrodynamics setup is to allow the generation of non-classical states of
the field. Therefore, it is interesting to fully characterize them. We present, in
the last chapter of this work, a method to directly measure the Wigner function of
any state of the cavity, and its implementation for a one-photon Fock state.
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Contributor : Patrice Bertet <>
Submitted on : Friday, February 28, 2003 - 4:16:25 PM
Last modification on : Thursday, December 10, 2020 - 12:37:54 PM
Long-term archiving on: : Tuesday, September 11, 2012 - 8:00:10 PM


  • HAL Id : tel-00002496, version 1


Patrice Bertet. Atomes et Cavité : Complémentarité et Fonctions de Wigner. Physique Atomique [physics.atom-ph]. Université Pierre et Marie Curie - Paris VI, 2002. Français. ⟨tel-00002496⟩



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