https://doi.org/10.1140/epjd/e2019-90672-4
Regular Article
Resonant excitations of a Bose Einstein condensate in an optical lattice
1
Université de Toulouse, UPS, Laboratoire Collisions Agrégats Réactivité, IRSAMC, F-31062 Toulouse, France
2
CNRS, UMR 5589, F-31062 Toulouse, France
3
Marian Smoluchowski Institute of Physics, Jagiellonian University, Łojasiewicza 11, PL-30348 Kraków, Poland
a e-mail: david.gueryodelin@gmail.com
Received:
6
December
2018
Accepted:
14
June
2019
Published online:
16
August
2019
We investigate experimentally a Bose Einstein condensate placed in a 1D optical lattice whose phase or amplitude is modulated in a frequency range resonant with the first bands of the band structure. More precisely, we study the effect of the strength of a weak extra external confinement superimposed to the lattice on the 1 and 2-phonon transitions. We identify lines immune or very sensitive to the external confinement despite many orders of magnitude of difference in strength compared to the lattice. We interpret those features and present 1D numerical simulations including atom-atom interactions consistent with the experimental observations. Using the band mapping technique, we also get a direct access to the populations that have undergone n-phonon transitions for each modulation frequency including for non-zero quasi-momentum.
Key words: Cold Matter and Quantum Gas
© EDP Sciences / Società Italiana di Fisica / Springer-Verlag GmbH Germany, part of Springer Nature, 2019