Spectroscopy of Rydberg atoms in a high-magnetic-field atom trap

We study cold Rydberg atoms and their interactions in a high-magnetic-field atom trap with a central magnetic field of 2.6 Tesla. The presence of the large magnetic field creates a wide spectrum of non-degenerate Rydberg states that can be tailored towards Rydberg-atom interaction experiments by fine-tuning the magnetic field and adding a longitudinal electric field. To enable these experiments, we have calculated the spectra of high-lying Rydberg states of Rubidium 85 in parallel magnetic and electric fields, taking all known quantum defects and fine-structure effects into account. We identify near-degenerate pairs of states with equal magnetic quantum number and opposite $z$-parity (for electric field zero). These states couple strongly when a parallel electric field is applied, resulting in large, tunable permanent electric dipole moments that should enhance Rydberg-Rydberg interactions. Field tuning can also be used to induce energy exchange resonances (F\"{o}rster resonances). In this presentation, we will discuss the calculated spectra and spectroscopic measurements on Rydberg atoms in the magnetic atom trap. Progress towards superimposing a far-off-resonant optical trap onto the high-magnetic-field trap is also reported.