Enhanced Heat Flow in the Hydrodynamic Collisionless Regime

Atom Optics and Ultrafast Dynamics, Utrecht University, P.O. Box 80,000, 3508 TA Utrecht, The Netherlands.
Physical Review Letters (Impact Factor: 7.51). 08/2009; 103(9):095301. DOI: 10.1103/PhysRevLett.103.095301
Source: PubMed


We study the heat conduction of a cold, thermal cloud in a highly asymmetric
trap. The cloud is axially hydrodynamic, but due to the asymmetric trap
radially collisionless. By locally heating the cloud we excite a thermal dipole
mode and measure its oscillation frequency and damping rate. We find an
unexpectedly large heat conduction compared to the homogeneous case. The
enhanced heat conduction in this regime is partially caused by atoms with a
high angular momentum spiraling in trajectories around the core of the cloud.
Since atoms in these trajectories are almost collisionless they strongly
contribute to the heat transfer. We observe a second, oscillating hydrodynamic
mode, which we identify as a standing wave sound mode.

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