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Q-Farm Seminar Series: Peter Asenbaum and Wil Kao, Stanford University

December 4, 2019 - 12:00pm
PAB 102/103
Wil Kao and Peter Asenbaum

Equivalence Principle and atom interferometry - Peter Asenbaum


Precision tests of the equivalence principle probe perturbations to geometric gravity and exotic ultra-weak interactions. Freely falling atoms are ideal test particles for precision measurements. The atoms are split and recombined in a light pulse interferometer to suppress sensitivity to initial conditions and to readout position changes on the nanometer scale. By using two different Rubidium isotopes simultaneously, we create a local sensor that is sensitive to unknown interactions that couple differently to the two isotopes. For a free fall time of 2s we achieve an acceleration sensitivity of 2.5 × 10−11 g. However, differences in spatial degrees of freedom, mass, level structure and magnetic moment lead to systematic errors. I will present our current understanding of the systematic errors and the techniques we use to suppress them.

 

Dipolar stabilization of a strongly correlated, highly excited quantum gas in quasi-1D - Wil Kao

We present the first experimental realization of a Luttinger liquid with both short-range contact and long-range dipole-dipole interactions by trapping ultracold dysprosium in quasi-1D. We observe that a quantum quench of the contact interaction from strongly repulsive to strongly attractive smoothly connects its ground state to a strongly correlated, highly excited metastable state. This is unusual because most excited many-body systems undergo rapid thermalization, preventing highly excited eigenstates from being investigated experimentally. By contrast, in our system with repulsive dipole-dipole interactions, collective excitation measurements reveal that such a state remains dynamically stable against soliton-like cluster formation across the full range of attractive contact interaction strengths. Generic thermal states of similar energy density can be accessed via a different state preparation protocol, suggesting that a novel quantum many-body scar-like state has been realized.