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CONDENSED MATTER AND STATISTICAL PHYSICS SECTION
	
INFORMAL SEMINAR on  Disorder and strong electron correlations




Thursday, 23 February    -    11:00 a.m.



Room 239,  Main Bldg.- II floor



E. MARIANI    ( The Weizmann Institute of Science, Rehovot )



"Mott insulator-superfluid domains for confined BEC in optical lattices"


	Abstract

Bose Einstein Condensates in optical lattices under an external 
confinement are expected to form coexisting Superfluid and 
Mott-Insulating domains [1] reminiscent of the quantum phase transition 
for the infinite system [2].  The experimentally observed transition 
[3] is presently ascribed to relative shrinking/widening of the 
different domains.  The presence of superfluid domains and the 
excitations of the interfaces between the two phases play a crucial 
role in the time evolution of the system under modulations of the 
parameters of the system as well as in its thermodynamic properties.
In this work we derive the dispersion relation of the surface waves at 
the interfaces between Mott-Insulating and Superfluid phases.  We then 
calculate their contribution to the heat capacity of the system and 
show how its low temperature scaling allows a direct experimental test 
of the existence and properties of Mott-Superfluid domains [4].  A 
further independent probe of the domains is considered studying the 
response of the system to a periodic modulation of the intensity of the 
optical lattice.  The induced parametric resonances of the superfluid 
excitations are reflected in the energy absorption by the atomic cloud, 
yielding information about the structure of different domains.

[1] D. Jaksch et al. , Phys. Rev. Lett. 81, 3108 (1998)
[2] M. P. A. Fisher et al. , Phys. Rev. B 40, 546 (1989)
[3] M. Greiner et al. , Nature 415, 39 (2002)
[4] E. Mariani and A. Stern, Phys. Rev. Lett. 95, 263001 (2005)