Bulletin of the American Physical Society
2006 Four Corners Section of the APS Fall Meeting
Friday–Saturday, October 6–7, 2006; Logan, Utah
Session E1: Physics in the Four Corners Region II |
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Chair: Bill Fairbank, Colorado State University Room: Eccles Conference Center Room 216 |
Friday, October 6, 2006 3:45PM - 4:21PM |
E1.00001: Imaging coherent electron flow in a two-dimensional electron gas Invited Speaker: Images of electron flow through a two-dimensional electron gas are obtained at liquid He temperatures using scanning probe microscopy. Near a quantum point contact (QPC), the images show angular lobe patterns characteristic of the wavefunctions in the QPC. At distances greater than one micron from the QPC, narrow branches of electron flow are observed due to the cumulative effect of small angle scattering. All of the images are decorated by interference fringes spaced by half the Fermi wavelength demonstrating that the flow is coherent. To determine the origin of the interference fringes, an imaging interferometer is created by adding a circular reflecting gate. The strength and position of the interference fringes can then be controlled by the voltage on this reflecting gate. Using the interferometer, we show that the interference fringes are due to backscattering to the QPC. Both experiments and theory demonstrate that the interference signal is robust against thermal averaging. [Preview Abstract] |
Friday, October 6, 2006 4:21PM - 4:57PM |
E1.00002: Creating Cold Molecules Invited Speaker: The techniques of laser cooling and trapping have transformed atomic physics. The ease of obtaining ultracold atomic samples with these methods has led to new experimentally realizable quantum systems, including the dilute gas Bose-Einstein condensate and the degenerate Fermi gas. After several decades of rapid growth in the field of atom cooling and trapping, the obvious next step is to extend these studies to cold molecules. Molecules have a rich internal energy structure, creating new research opportunities in quantum chemistry, novel collision studies, and collective quantum effects. Cold molecular packets are produced by supersonic expansion coupled with Stark deceleration. First the molecules undergo the expansion process, which cools both the external and internal degrees of freedom. The resulting molecular beam is then slowed to rest by the method of Stark deceleration. Stark deceleration uses the molecules' interactions with inhomogenous electric fields to decelerate the beam. The molecules are then trapped electrostatically, where their collisions can be studied. [Preview Abstract] |
Friday, October 6, 2006 4:57PM - 5:33PM |
E1.00003: High Pressure Physics: Thinking Outside the Box Invited Speaker: I will present examples where thinking outside the box has led to unexpected developments, economic success, and new understanding of the underlying physics. As example of economic success I will present the development of a multipass Brillouin interferometer, which has revolutionized solid state Brillouin scattering experiments. Scientific examples discussed will be alkali cyanides and Chromium alloys. [Preview Abstract] |
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