Session G2: Atomic, Molecular, and Optical Physics (Invited)

Quantum dynamical behavior near a phase transition in antiferromagnetic spinor Bose-Einstein condensates

Many-body quantum dynamics has come under intense focus in recent years, with a variety of experimental systems—atoms, ions and solid state qubits--emerging as key platforms for inquiry. One key set of questions concerns the ability of any such delicately tailored quantum system to relax to equilibrium when it is isolated from the environment. In this talk I will present our group’s efforts to address this question using magnetic quantum fluids comprised of Bose-Einstein condensed atoms (BECs). A key experimental discovery of our group in recent years is the existence of a sharp phase boundary in antiferromagnetic sodium BECs through quantum quench dynamics. In this talk I will show data demonstrating the rich interplay between many actors--spin-spin interactions, the influence of external magnetic fields, and the spatial quantum dynamics of many interacting modes that all compete to determine the non-equilibrium behavior.   

Shockwaves in a strongly interacting Fermi gas

We study the hydrodynamics of a strongly interacting, ultracold atomic Fermi gas near the superfluid phase transition. Specifically, we focus on the formation of shockwaves caused by splitting and colliding a cigar-shaped atomic sample. Separation of the sample is accomplished with a digital micro-mirror device (DMD), which can be used to generate arbitrary shaped potentials. The shockwaves, characterized by sharp, nearly discontinuous edges, are well modeled by the Navier-Stokes equation with the presence of shear viscosity. Additionally, we are able to determine from the data the velocity field, which approaches supersonic flow in the limit of large initial cloud separation. We study properties of the shockwave versus temperature in the superfluid and normal fluid phases.   

Laser Spectroscopy and Cooling of Atomic Gadolinium

Lanthanide elements are of interest because of their complex internal structures and large ground state magnetic moments. These unique features can provide solutions to help overcome current challenges and obstacles in quantum phenomenon that are not possible with other atomic species traditionally used in ultracold atom experiments. We present results on high resolution spectroscopy and progress towards laser cooling and trapping of atomic gadolinium (Gd). Laser cooling and trapping Gd will serve as the starting point for novel investigations into next generation frequency standards, quantum enhanced metrology, and ultracold dipolar physics.   

Probing Ion Irradiation Effects with Buried Interface Devices

In this talk I will discuss our efforts to understand the energy loss of impacting multicharged ions in oxides. These ions possess uniquely high potential energies which have been shown to create surface features such as craters and hillocks. However, the full impact of their potential energy loss post-impact has not been fully explored. For example, below the surface the ions will lose energy continuously before coming to a rest. This energy loss per unit distance or stopping power of the ions within the solid matrix is predicted to depend on the charge state of the ions. In particular, the dynamical screening of the charge inside the solid is proposed to give rise to a pre-equilibrium stopping that will have a power law dependence on the charge state. We have explored this topic using metal-oxide-semiconductor (MOS) devices that contain oxides irradiated with multicharged Argon ions. As I will show, multiple aspects of the capacitance-voltage or C-V characteristics of these MOS devices scale with the ion charge state of the impacting Argon ions in a manner consistent with the expectations of pre-equilibrium stopping.