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K. E. Wilson

Publications and source records attributed to K. E. Wilson.

4 recordsLinked to original sources

Deterministic Nucleation and Dynamics of Infilled Multiply-Charged Vortices in an Immiscible $^{87}\mathrm{Rb}$-$^{41}\mathrm{K}$ Mixture

We propose a method for controllably generating multiply-charged vortices in immiscible Bose-Einstein condensates. We achieve this by applying a laser stirring technique to a $^{87}\mathrm{Rb}$-$^{41}\mathrm{K}$ mixture, where the vortices generated are infilled by the secondary component. We numerically demonstrate that the charge of the vortex can be tuned reproducibly by varying the stirring parameters, allowing the deterministic generation of stable infilled vortices with high topological charge. We then consider the dynamics of these multiply-charged vortices in a circular trap; in contrast to single-component condensates, we observe long-lived precession of the multiply-charged vortices with a charge dependent frequency and collective breathing modes of the infilling component. For specific large winding numbers, we observe distinct dynamical instabilities leading to vortex dislocation.

cond-mat.quant-gas

Deterministic creation, pinning, and manipulation of quantized vortices in a Bose-Einstein condensate

We experimentally and numerically demonstrate deterministic creation and manipulation of a pair of oppositely charged singly quantized vortices in a highly oblate Bose-Einstein condensate (BEC). Two identical blue-detuned, focused Gaussian laser beams that pierce the BEC serve as repulsive obstacles for the superfluid atomic gas; by controlling the positions of the beams within the plane of the BEC, superfluid flow is deterministically established around each beam such that two vortices of opposite circulation are generated by the motion of the beams, with each vortex pinned to the \emph{in situ} position of a laser beam. We study the vortex creation process, and show that the vortices can be moved about within the BEC by translating the positions of the laser beams. This technique can serve as a building block in future experimental techniques to create, on-demand, deterministic arrangements of few or many vortices within a BEC for precise studies of vortex dynamics and vortex interactions.

cond-mat.quant-gas

Experimental Methods for Generating Two-Dimensional Quantum Turbulence in Bose-Einstein Condensates

Bose-Einstein condensates of dilute gases are well-suited for investigations of vortex dynamics and turbulence in quantum fluids, yet there has been little experimental research into the approaches that may be most promising for generating states of two-dimensional turbulence in these systems. Here we give an overview of techniques for generating the large and disordered vortex distributions associated with two-dimensional quantum turbulence. We focus on describing methods explored in our Bose-Einstein condensation laboratory, and discuss the suitability of these methods for studying various aspects of two-dimensional quantum turbulence. We also summarize some of the open questions regarding our own understanding of these mechanisms of two-dimensional quantum turbulence generation in condensates. We find that while these disordered distributions of vortices can be generated by a variety of techniques, further investigation is needed to identify methods for obtaining quasi-steady-state quantum turbulence in condensates.

cond-mat.quant-gas

A Large Solid Angle Study of Pion Absorption on He3

Measurements have been made of pi+ absorption on He3 at T_pi+ = 118, 162, and 239 MeV using the Large Acceptance Detector System (LADS). The nearly 4pi solid angle coverage of this detector minimizes uncertainties associated with extrapolations over unmeasured regions of phase space. The total absorption cross section is reported. In addition, the total cross section is divided into components in which only two or all three nucleons play a significant role in the process. These are the first direct measurements of the total and three nucleon absorption cross sections.

nucl-th