Abstract
We consider the quench of an atomic impurity via a single Rydberg excitation in a degenerate Fermi gas. The Rydberg interaction with the background gas particles induces an ultralong-range potential that binds particles to form dimers, trimers, tetramers, etc. Such oligomeric molecules were recently observed in atomic Bose-Einstein condensates. In this work, we demonstrate with a functional determinant approach that quantum statistics and fluctuations have observable spectral consequences. We show that the occupation of molecular states is predicated on the Fermi statistics, which suppresses molecular formation in an emergent molecular shell structure. At large gas densities this leads to spectral narrowing, which can serve as a probe of the quantum gas thermodynamic properties.
Highlights
The study of bound complexes composed of a large number of particles lies at the heart of physics, chemistry, and biology
Rydberg excitations in a Fermi gas are an example for systems where quantum mechanics and statistics can appear in surprising places: The atoms bound in the molecular shells are localized on a length scale that is much smaller than the inverse Fermi momentum
We have developed a time-dependent many-body formalism based on functional determinants that treats the bound Rydberg molecules and scattering states on the same footing, to follow the nonequilibrium time evolution of the degenerate Fermi gas interacting with a spatially extended Rydberg impurity
Summary
The study of bound complexes composed of a large number of particles lies at the heart of physics, chemistry, and biology. Examples include DNA formed from nucleotides, complex molecules composed of atoms, and nuclei comprised of neutrons and protons Our understanding of these complex systems emerges from idealized models, which are yet sufficiently complex to contain the relevant physics. The shell structure we describe here for fermions is akin to the nuclear shell model and arises because at low gas density few-body bound molecular states must obey the Pauli exclusion, leading to a sequential filling of molecular shells. Rydberg excitations in a Fermi gas are an example for systems where quantum mechanics and statistics can appear in surprising places: The atoms bound in the molecular shells are localized on a length scale that is much smaller than the inverse Fermi momentum. VI by outlining experimental protocols to measure the predicted phenomena and providing an outlook
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