CQOM Talk

Steffen Meyer

Title: Direct frequency-comb-driven Raman transitions in the THz range: Qubit manipulation and high resolution spectroscopy of single ions

15:15-15:30 Questions and coffee/tea and cake

Invited talk

T. C. Killian, Rice University, Department of Physics and Astronomy and Rice Center for Quantum, Materials, Houston, Texas, USA

Title: From Ultralong-range Molecules to Rydberg Polarons in a Bose Gas

Abstract:

I will describe the excitation of Rydberg atoms in a Bose-Einstein condensate of strontium atoms. In a few-body regime, we observe a dense, highly structured spectrum reflecting excitation of ultralong-range molecules consisting of one or more ground-state atoms bound to the Rydberg core in potential wells formed by the Rydberg-electron wave function. In a many-body regime, with hundreds of ground-state atoms within the Rydberg orbital, the Rydberg atoms can be viewed as an impurity in a quantum gas, connecting to important concepts in condensed matter physics. The spectrum for impurity excitation displays signatures of polaronic states, in which the Rydberg atom significantly perturbs the density of the background Bose gas. In particular, detailed analysis of the red-detuned tail of the excitation spectrum reveals the intrinsic excitation spectrum of Rydberg polarons, free from non-linear effects,   density averaging, and the perturbing influences of shape resonances. All features of the spectrum are well described using functional determinant theory to solve the many-body Hamiltonian. I will also describe progress towards creating Rydberg polarons in a quantum degenerate Fermi gas.

Research supported by the Air Force Office of Scientific Research, National Science Foundation, and the Robert A, Welch Foundation

Collaborators

F. B. Dunning¹, F. Camargo¹, J. Whalen¹, R. Ding¹, H. R. Sadeghpour², R. Schmidt^2,3, E. Demler³, S. Yoshida⁴, J. Burgdorfer⁴

¹Rice University, Department of Physics and Astronomy and Rice Center for Quantum Materials, Houston, Texas

²ITAMP, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts

³Department of Physics, Harvard University, Cambridge, Massachusetts

⁴Institute for Theoretical Physics, Vienna University of Technology, Vienna, Austria, EU