Friedemann Landmesser

Femtosecond (fs) interferometry combined with acousto-optical phase modulation is an effective approach to implement various types of coherent nonlinear and multidimensional spectroscopy schemes. Here, we focus on gaseous and ultracold samples and compare directly the performance and spectral resolution between two experimental implementations of the phase modulation technique, which are stepwise and continuous rapid scanning of the underlying Fourier transform (FT) interferometers.

Abstract Tailored light–matter interactions in the strong coupling regime enable the manipulation and control of quantum systems with up to unit efficiency1,2, with applications ranging from quantum information to photochemistry3,4,5,6,7.

Abstract Femtosecond coherent multidimensional spectroscopy is demonstrated for an ultracold gas. A setup for phase modulation spectroscopy is used to probe the 32S1/2–22P1/2,3/2 transition in an $800\,\mathrm{\mu}$K-cold sample of 7Li atoms confined in a magneto-optical trap. The observation of a double quantum coherence response, a signature of interparticle interactions, paves the way for detailed investigations of few- and many-body effects in ultracold gases using this technique.