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SUMMARY:Probing the equation of state of Bose and Fermi gases - Nir Navon 
 (Laboratoire Kastler-Brossel)
DTSTART:20110921T143000Z
DTEND:20110921T160000Z
UID:TALK33181@talks.cam.ac.uk
CONTACT:6270
DESCRIPTION:The quantum many-body problem is at the heart of some of the m
 ost formidable open problems in modern physics\, such as high-T$_c$ superc
 onductivity or the behaviour of neutron stars. Ultracold atomic systems ca
 n now be used to simulate model Hamiltonians of condensed matter or nuclea
 r physics\, in very well-controlled environnement. In this talk\, I will p
 resent a general method that we have developed to probe the thermodynamics
  of homogeneous quantum systems using trapped atomic gases. These measurem
 ents are directly compared to the predictions of theories of the quantum m
 any-body problem. We have applied this technique to the spin-1/2 Fermi gas
  and the Bose with short-range interactions. Using fermionic 6Li\, we expl
 ored a part of the wide parameter space by changing the interaction streng
 th\, the spin-population imbalance or the temperature of the gas. This sys
 tem exhibits remarkably rich physics\, such as normal/superfluid phase tra
 nsitions (that can be of thermal or quantum character) or a Fermi liquid-t
 ype behaviour of the normal phase. We have also used this method to probe 
 a Bose gas of 7Li atoms close to a Feshbach resonance. We have measured th
 e Equation of State of the Bose gas as a function of interactions at very 
 low temperature. For the first time\, we measured quantitatively the Lee-H
 uang-Yang beyond mean-field correction to the ground-state energy of the s
 ystem\, first predicted in 1957. We compared the experimental results to Q
 uantum Monte-Carlo calculations. We have extended this study using out-of-
 equilibrium measurements of the Bose gas in the strongly interacting regim
 e\, which gives a first hint on the properties of the hypothetical unitary
  Bose gas
LOCATION:Rutherford building\, Seminar Room B
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