Heidelberg 2015 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 11: Quantum Gases: Fermions II

Q 11.5: Talk

Monday, March 23, 2015, 15:45–16:00, K/HS2

Thermometry of fermionic atoms in optical lattices by modulation spectroscopy — •Karla Loida and Corinna Kollath — HISKP, Universität Bonn, Nussallee 14-16, 53115 Bonn

The possibilities to probe and accurately characterize an ultracold Fermi gas trapped in an optical lattices are still very limited. In particular, experimentalists lack reliable methods to adequately measure the temperature. We propose a scheme to directly measure the temperature of non-interacting fermionic atoms confined to a three-dimensional optical lattice by superlattice modulation spectroscopy. The superlattice modulation is applied along one direction and injects momentum into the system which strongly affects the nature of excitations. This leads to a strong temperature dependence of the spectral response such that the temperature may be easily extracted from a fit with a minimum of fitting parameters. Moreover, the experimental realization is temptingly simple since the spectral response can be determined from adiabatic band mapping when exciting to higher bands owing to the fact that the superlattice modulation only excites distinct quasimomenta. This scheme extends down to very low temperatures of about 10% of the hopping strength that have not been observed in experiment so far and that lie below the Néel temperature where antiferromagnetic ordering is expected to occur.