Fermion pairing and thermodynamics under a bilayer microscope*

Understanding interacting quantum systems is a central goal of modern physics. In this talk, I describe the creation of a novel bilayer quantum gas microscope for fermions which enables full detection of spin and charge in large arrays containing thousands of interacting atoms.

We use this technique to probe the local fluctuations within strongly-interacting fermionic systems, and to connect these fluctuations to many-body order. By tuning the strength and sign of interactions, we realize the crossover from a Mott insulator with strong repulsion to a gas of local pairs with strong attraction. At intermediate attraction, we observe correlated and overlapping fermion pairs extending over multiple lattice sites. Within the repulsive Mott insulator, we detect local doublon-hole quantum fluctuations, a direct signature of super-exchange, which in turn establishes long-range magnetic order. Further leveraging the technique of full density imaging, we implement model-independent thermometry using the density fluctuation-dissipation theorem. Finally, we invent and realize a novel method to coherently manipulate and entangle fermion pairs in an optical lattice, with applications including robust quantum information storage and hybrid analog-digital quantum simulation.

*Thesis advisor: Martin Zwierlein, Massachusetts Institute of Technology.