Physics Graduate Brochure - Physics - North Carolina State University

Hydrodynamic expansion:
Elliptic Flow and Perfect Fluidity
Released from a cigar-shaped optical trap, the gas
expands rapidly in one direction, while remaining
nearly stationary in the other direction. This so-called
elliptic flow was first observed by our group in 2002
and is a feature shared with a quark-gluon plasma
(QGP), a state of matter that existed microseconds
after the Big Bang, and recreated in heavy ion
experiments.
A recent conjecture from the string theory community
defines a perfect normal fluid (not a superfluid) as one
with a minimum ratio of shear viscosity to entropy
density. For the Fermi gas, we directly measure the
entropy and the shear viscosity, as functions of the
energy and temperature. Although a QGP is 19 orders
of magnitude hotter and 25 orders of magnitude more
dense than an ultra-cold atomic Fermi gas, both
systems are nearly perfect fluids.
Nonlinear Quantum Hydrodynamics:
Shock Waves
The repulsive potential of a focused green laser beam
slices a trapped Fermi gas into two pieces.
Extinguishing the green beam, the two pieces collide
in the optical trap, producing shock waves, manifested
in the sharp edges appearing in the density. These
experiments provide a new paradigm for exploring
nonlinear quantum hydrodynamics, with magnetically
tunable strong interactions in both the normal and
superfluid regimes.
Experiments at JETLAB
Current and planned experiments include quantumconfined
Fermi gases in two-dimensional standingwave
traps, universal transport and bulk viscosity in
the strongly interacting regime, generation and control
of atomic spin current, optical control of interactions
and dispersion, and non-equilibrium dynamics. We
are also very interested in the application of optical
cooling techniques and quantum measurement
methods to control and study nano-mechanical
systems, such as membranes, cantilevers and rotors.
Further Information
We encourage interested applicants to visit the JETLAB webpage, www.phy.duke.edu/research/photon/qoptics.
This contains a link to the new location of JETLAB at NC State University. Prospective students can contact Prof.
John Thomas directly (john_thomas@ncsu.edu) or the Graduate Program office at py-grad-program@ncsu.edu.
.NC STATE Physics.
www.physics.ncsu.edu