Probing strongly driven quantum matter with ultracold strontium

We present the latest results from an analog quantum simulation platform based on Bose-condensed strontium. 

In the first project, we study the effects of external driving on atoms in a quasiperiodic optical lattice. This driven 1D quasicrystal maps onto an irradiated integer quantum Hall system, enabling study of polarization-dependent light-induced transport phenomena in a highly controlled setting. By tuning drive amplitude and polarization, we observe an interlaced phase diagram of localization–delocalization transitions, including an extended critical regime featuring multifractal eigenstates and anomalous transport. Looking ahead, the same experimental toolkit can be extended to engineer both spatially inhomogeneous tunneling and position-dependent weak measurement in optical lattices.

In the second project, we report the first observation of the long-predicted phenomenon of strong-field stabilization, using an analog quantum simulator of laser-atom interactions based on Bose-condensed atoms in a shaken optical trap. Large-amplitude waveform-programmable shaking enables the study of ultrafast and strong-field dynamics that are otherwise difficult to realize due to laser intensity requirements. Beyond a threshold shaking amplitude, we observe that the loss rate levels off and then decreases, constituting strong-field stabilization of the ground state in the low-frequency regime. This phenomenon is accompanied by a spatial dichotomy of the density, as predicted by approximate theories which have been debated in the strong-field community for decades. These analog quantum simulation methods could be extended to study multifrequency strong-field dynamics and high-harmonic generation.