Group Seminar at MPQ and Zoom: A trip to the quantum zoo: from a diatomic molecule to a tight-binding lattice

Matthew Eiles, MPIPKS Dresden
Group Seminar at MPQ lecture hall and Zoom
Tuesday, June 20th , 09:00 am (MEZ)

Abstract:

I will discuss an exotic class of diatomic molecules composed of a Rydberg atom and an atom in its ground state. Although these molecules appear to be, at the level of their constituent atoms, little more complicated than the hydrogen molecule, their highly excited electronic states reveal rich physics at nearly macroscopic dimensions. I will show how the unusual binding mechanism of these molecules, relying on the scattering of the Rydberg electron off of the ground state atom, can be reformulated and interpreted using a ”dressed ion pair” model. This model comes with a twist: the charge on the negative ion is much smaller than that of an electron. With this approach we can predict an infinitely large collection of these quantum creatures.

Following this, I will show how the ideas presented above in the context of molecular formation can also be used to map the electronic spectrum of a Rydberg atom in the presence of several ground state atoms to the spectrum of a tight-binding Hamiltonian. By simultaneously increasing the number of ground state atoms and the level of excitation of the Rydberg atom, for which the Coulomb potential supplies infinitely many and highly degenerate excited states, we can approach theoretically a thermodynamic limit using a single Rydberg atom. Our study reveals a surprising connection to an archetypal concept of condensed matter physics, Anderson localization.