Quantum Hopping on a Lattice of Cold Rydberg Atoms

Carolijn van Ditzhuijzen, Ben van Linden van den Heuvell, Bart Noordam

In this project we aim to make a lattice of interacting Rydberg atoms. These Rydberg atoms are all in the n=60 state (the "lower state"), except for one, which is in the n=61 state (the "upper state"). Through dipole-dipole interactions, the atoms on different lattice sites can exchange excitations. That is to say atom A at site 1 can be excited from n=60 to n=61, while atom B at site 2 is de-excited from n=61 to n=60. In fact the quantum excitation (n=61) can hop from one side to the next.

The experiment will be performed with 100 ÁK rubidium atoms in a Magneto-Optical Trap (MOT). Two pulsed dye lasers at a different wavelength, focused at different positions in the cold atom cloud (▒ 20 Ám apart) create the Rydberg atoms by a two-photon transition. A slowly ramped electric field ionizes the different Rydberg states subsequently (State selective Field Ionization (SFI)) and the electrons are detected on a Micro-Channel Plate (MCP). This way we sample on each site the upper and lower state probability. The sampling rate is higher than the hopping time, which is in turn higher than the moving time, so we expect to be able to follow the evolution of the excitation.

The fact that we will be able to follow the upper and lower state population of individual sites in a time-dependent manner makes this system unique. From the study of this model system we aim to obtain insights relevant to other fields such as: quantum random walk, multiple scattering and localization and propagation of plasmonics waves in nanoparticles.

The project is theoretically supported by Francis Robicheaux from the University of Auburn in Alabama, USA.