Light Scattering by Ultracold Atoms in Optical Lattices
Dipl. Phys. Stefan Rist, Universitat Autonoma de Barcelona
Th, 8.1.2009, 11.00 Uhr
N24/252
In the first part light scattering by an ultracold atomic gas in a
one-dimensional optical lattice is theoretically studied, when the
atoms are probed by a weak laser. We analyze the intensity of the
scattered light as a function of the angle of emission for different
values of the tunneling rate, spanning from the superfluid to the
Mott-insulator phase. We show how the excitation spectrum of the
many body system can be measured by observing of the scattered light
intensity as a function of the scattering angle and photon frequency.
We identify different features in the first order coherence of the
scattered light, depending on whether the atoms are in the Mott-insulator
or superfluid state. We discuss our results with respect to previous
studies, where the structure form factor was evaluated by a time-of-flight
measurement [1] and where light scattering by ultracold atoms in an
optical lattice was determined, neglecting the tunneling rate [2].
In the second part we study theoretically the photonic spectrum of a
bichromatic optical lattice, in the regime in which the atoms are well
localized in the lattice sites and their dipolar transitions couple
weakly to the probe light. The photonic spectrum is characterized as
a function of the interparticle distance D inside the primitive
Wigner-Seitz cell. Depending on D and on the atomic species composing
the Wigner-Seitz cell, two or more photonic bandgaps can be found.
We then determine the dynamics, when the atoms couple to the
standing-wave mode of a Fabry-Perot cavity, and study the cavity
transmission spectrum in the strong coupling regimei
[1] A.M. Rey et al., Phys. Rev. A 72, 023407 (2005)
[2] I.B.Mekhov et al., Phys. Rev. Lett. 98, 100402 (2007)
