Ponderomotive Optical Lattice Trap for Rydberg Atoms
Georg Raithel lab, University of Michigan
Participating Students: Yun-Jhih Chen, Kaitlin Moore, Andira Ramos
(Illustration credit: Kelly Younge)
In this project, we develop and study an optical lattice as a trap for Rydberg atoms.
We also employ this Rydberg-atom trap in applications, such as performing a high-precision measurement of the Rydberg constant.
What are Rydberg atoms?
Rydberg atoms are atoms in highly excited states (large principal quantum number, n). Their name comes from the Rydberg formula which describes the energy levels of the hydrogen atom. The energy levels of the Rydberg atom can be described by a modified Rydberg formula, since the outermost electron of a Rydberg atom sees an
ionic core which is like the hydrogen nucleus. When atoms are in Rydberg states, they take on exaggerated properties, such as extreme field sensitivity, lifetimes of hundreds of microseconds, and sizes that are thousands of times larger than ground state atoms.
Why study Rydberg atoms?
The exaggerated properties of Rydberg atoms make them useful for both the study of basic physics and employment in applications. For example, in basic physics, we could use Rydberg atoms to determine some fundamental constants more precisely. Potential applications of Rydberg atoms include extremely sensitive field sensors and a physical manifestation of a quantum computer.
What is an optical lattice?
An optical lattice is made by interfering laser beams and forms a series of wells that can trap atoms similarly to how an egg carton holds eggs (see illustration below). In our experiment, the optical lattice is formed by two counter-propagating 1064 nm laser beams, forming a one-dimensional series of wells. Ground-state Rubidium atoms in our lattice are trapped at regions of intensity maximum (i.e. the bottoms of the wells correspond to regions of intensity maximum).
Why is an optical lattice trap for Rydberg atoms special?
In order to harness the unique properties of Rydberg atoms for applications, it is necessary to have a Rydberg trap that provides careful control of the position of and the interactions among Rydberg atoms. Other proposed or realized Rydberg traps utilize static electric or magnetic fields that lead to massive energy level shifts in the atom. The optical lattice trap for Rydberg atoms, however, offers the benefit of minimal perturbation to the atomic energy levels. This minimal perturbation is necessary for such applications as high precision spectroscopy for improved determination of certain fundamental constants or for quantum information processing.
A cloud of atoms from our magneto-optical trap distorted into the shape of a Michigan 'M'.