Dynamics of Fermi gases in periodic potentials

We study the transport of ultra cold atoms in a tight optical lattice.
For identical fermions the system is insulating under an external force
while for bosonic atoms it is conducting. This reflects the di erent
collisional properties of the particles and reveals the role of
inter-particle collisions in establishing a macroscopic transport in a
perfectly periodic potential. The insulating behavior of the system is
connected to the nature of the periodic potential. In fact the atoms in
the lattice perform Bloch oscillations if an external force is applied.
In case of identical fermions, in absence of any interactions between
the particles, these oscillations can last many periods as observed
experimentally. From the determination of the Bloch period we can
directly measure the external force acting on the atoms realizing the
first atomic interferometer with degenerate fermions.