Quantum Cafe: Frédéric Chevy

Quantum Café is CCQ’s ongoing seminar series: open to all bona fide members of the greater NYC scientific community and held every second week, Quantum Café presents a series of informal, highly interactive talks, typically by external speakers, which present the most interesting recent developments and open questions in our field.

Title: Conductivity spectrum of ultracold atoms in optical lattices

Abstract: In this talk, I will discuss recent experiments probing the current response of an ensemble of ultracold atoms trapped in an optical lattice to a periodic modulation of the trapping potential. In the linear regime, we measure the real and imaginary parts of the associated conductivity as a function of lattice depth, temperature, interaction strength, and atom number. Experimental data is analyzed using complementary approaches, from sum-rules to kinetic theories that allow us to characterize relaxation mechanisms in the cloud. I will discuss in particular how the analysis of the high-frequency behaviour of the conductivity may provide a way to bridge the gap between harmonically trapped and homogeneous systems.