April 20 2014

22.-25.04.2014: visit of Pablo Barberis-Blostein

Pablo Barberis-Blostein (Mexico) visits us and will give a talk on Tuesday 22.04.2014 in the group seminar @09.00 in 4.18 with the title "Quantum beats, quantum beats light shifts, and quantum beats manipulation using postselection".

Ground state quantum beats observed in the second order intensity
correlation from a continuously driven atomic ensemble inside a two
mode optical cavity are subject to a frequency shift and
decoherence. While driving the cavity with light of linear
polarization ($\pi$ transitions) the second order autocorrelation
function is measured in the undriven mode (orthogonal polarization):
a first photon detection prepares a superposition of atomic
ground-state Zeeman sublevels and the second measures the ground
state beats. Between these two detections, the atoms can become
excited and return to the ground state, emitting most of the photons
into modes other than the cavity modes. Depending on the drive
strength this process can happen several times. Each time there is a
relative phase advance between the Zeeman sublevels. The information
of this phase advance and its associated decoherence is then leaked
into the modes that are not the cavity modes, which form the
environment. It is possible to get information about the number of
photons leaked into the environment by monitoring the driven
mode. Here we propose a scheme to manipulate the loss of amplitude
of the beats (decoherence) and the beat frequency shift, by
postselecting on the basis of information gathered through
measurement of the driven cavity mode. This proposal is a new
strategy compared with controlling the decoherence and light shift
through turning off the driven field.

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