Bulletin of the American Physical Society
38th Annual Meeting of the Division of Atomic, Molecular, and Optical Physics
Volume 52, Number 7
Tuesday–Saturday, June 5–9, 2007; Calgary, Alberta, Canada
Session P1: 2-Dimensional Physics |
Hide Abstracts |
Chair: V. Schweikhard, University of Colorado Room: TELUS Convention Centre Macleod D |
Friday, June 8, 2007 10:30AM - 11:06AM |
P1.00001: Bose gas in Flatland Invited Speaker: Physics of a Bose gas in two dimensions (2D) is quite different from the usual 3D situation. In a homogeneous 2D fluid of identical bosons long-range order is always destroyed by long wavelength thermal fluctuations, but the system can nevertheless become superfluid at a finite critical temperature. This phase transition does not involve any symmetry breaking and in the Berezinskii-Kosterlitz-Thouless (BKT) paradigm it is explained in terms of binding and unbinding of pairs of vortices with opposite circulations. Above the critical temperature, proliferation of unbound vortices is expected. Using optical lattice potentials we can create two parallel, independent 2D atomic clouds with similar temperatures and chemical potentials. When the clouds are suddenly released from the trapping potential and allowed to freely expand, they overlap and interfere. This realizes a matter wave heterodyning experiment which gives direct access to several features of the phase distributions in the two planes. Long wavelength phase fluctuations create a smooth and random variation of the interference fringes and free vortices appear as sharp dislocations in the interference pattern. Temperature study of these effects supports the BKT picture of the development of quasi-long-range coherence in these systems. \newline \newline [1] Zoran Hadzibabic, Peter Kruger, Marc Cheneau, Baptiste Battelier, and Jean Dalibard, Nature \textbf{441}, 1118 (2006). [Preview Abstract] |
Friday, June 8, 2007 11:06AM - 11:42AM |
P1.00002: Interference and dephasing dynamics in low dimensional condensates. Invited Speaker: Interacting condensates in one and two dimensions are subject to strong phase fluctuations, that prohibit the establishment of long range order. I will describe how these fluctuations affect the interference between two condensates. I will show that the average fringe contrast of interfering independent condensates scales as a non trivial power of the condensate size (or imaging area), which depends on the decay of spatial phase correlations within each condensate. For one dimensional systems I will also derive the full quantum distribution of the interference contrast. Measurement of this quantity lends access to highly non local quantum correlations. I will then discuss a matter wave interferometer, in which two condensates are initialized with a well defined relative phase. This phase is gradually randomized in the subsequent quantum dynamics. For weakly interacting one dimensional systems we derive an exponential decay of the phase coherence, at a rate that depends on the interaction strength and on hydrodynamic parameters. In two dimensions we find power law dephasing. This result is invalidated for sufficiently strong interactions in a way that may signal the emergence of a new regime of non equilibrium quantum dynamics. [Preview Abstract] |
Friday, June 8, 2007 11:42AM - 12:18PM |
P1.00003: Composite-fermionization of rapidly rotating bosons in two dimensions Invited Speaker: The non-perturbative effect of interaction can sometimes make interacting bosons behave as free fermions. The system of neutral bosons in a rapidly rotating atomic trap is equivalent to charged bosons coupled to a magnetic field, which has opened up the possibility of fractional quantum Hall effect like physics for bosons interacting with a short range interaction. Motivated by the composite fermion theory of the fractional Hall effect of electrons, we test the idea that interacting bosons map into non-interacting spinless fermions carrying one vortex each, by comparing wave functions incorporating this physics with exact wave functions available for systems containing up to 12 bosons. We find that the analogy of interacting bosons at ``filling factors'' $\nu=n/(n+1)$ with non-interacting fermions at $\nu^*=n$ provides a good account of the ground state as well as the low-energy excited states for small $n$, but interactions between fermions become increasingly important with increasing $n$. At $\nu=1$, which is obtained in the limit $n\rightarrow \infty$, the composite-fermionization overcompensate for the repulsive interaction between bosons, producing an attractive interactions between composite fermions, resulting in a paired state. [Preview Abstract] |
Friday, June 8, 2007 12:18PM - 12:54PM |
P1.00004: Bose-condensed states in 2D trapped gases Invited Speaker: I will discuss finite-size effects in trapped finite-temperature two-dimensional Bose gases, which include the formation of either true or quasicondensates. It will also be shown how the finite-size effects influence the crossover to the BEC regime. The second half of the talk will be dedicated to dipolar Bose gases in quasi2D geometries. I will shown how the excitation spectrum acquires the roton-maxon character and how one gets either collapsing or supersolid states when the roton minimum touches zero. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2022 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
1 Research Road, Ridge, NY 11961-2701
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700