Paul S. Julienne

Joint Quantum Institute

The University of Maryland and NIST

The collisions of cold and ultracold simple atoms such as alkali-metal species are quite well understood and, in many cases, can be precisely tuned in their elastic and inelastic properties using tunable threshold scattering resonances known as Feshbach resonances [1]. By contrast, complex atoms such as the Lanthanide species Er or Dy exhibit a dense set of overlapping chaotic resonances that are just beginning to be understood [2]. The species Dy is especially interesting since it has the largest magnetic dipole moment of any atom (10 Bohr magnetons), such that the anisotropic long range potential between two Dy atoms is dominated by the dipolar term that varies as the inverse cube of the distance between the atoms. While the Feshbach spectrum of two Dy atoms versus magnetic field exhibits a clear signature of a chaotic spectrum determined by a random matrix Hamiltonian, it also exhibits patterned structure that is explained by the emergence of a broad universal s-wave halo state in the midst of a sea of narrow chaotic resonances [3]. This talk will explore the two- and three-body physics of cold Dy atoms in such a domain of patterned complexity and examine some open questions that remain to be answered concerning the collisions and interactions of cold and ultracold molecules.

[1] C. Chin, R. Grimm, P. S. Julienne, and E. Tiesinga, Rev. Mod. Phys. 82, 1225-1286 (2010).

[2] T. Maier, H. Kadau, M. Schmitt, I. Ferrier-Barbut, T. Pfau, A. Frisch, S. Baier, K. Aikawa, L. Chomaz, M. J. Mark, F. Ferlaino, C. Makrides, E. Tiesinga, A. Petrov, and S. Kotochigova, Phys. Rev. X 5, 041029 (2015)

[3] T. Maier, I. Ferrier-Barbut, H. Kadau, M. Schmitt, M. Wenzel, C. Wink, T. Pfau, K. Jachymski, P. S. Julienne, Phys. Rev. A 92, 060702, Rapid Comm. (2015).