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SUMMARY:Josephson junctions for ultracold gases - Prof Markus Oberthaler (
 University of Heidelberg)
DTSTART:20091123T153000Z
DTEND:20091123T170000Z
UID:TALK20053@talks.cam.ac.uk
CONTACT:6270
DESCRIPTION:The recent realization of atomic Bose-Einstein condensates ope
 ns up the way to observe fundamental quantum mechanical effects on a macro
 scopic scale. Fortunately the situation is far from being an ideal gas rea
 lization and the interactions between particles play a crucial role and le
 ad to new phenomena [1]. \n\nWe will discuss a paradigm quantum effect nam
 ely tunnelling of Bose-Einstein condensates through a barrier. This situat
 ion is closely related to the physics of Josephson junctions known from we
 akly coupled superconductors. In contrast to the condensed matter experime
 nts the population difference as well as the phase difference can be direc
 tly measured and the atom-atom interaction leads to new dynamical modes wh
 ere tunnelling ceases to exist. It will also be discussed how this system 
 can be utilized for the realization of the smallest possible thermometer w
 hich allows for temperature measurements in a regime where standard method
 s fail. Finally some light will be shed on the fact that the experiments a
 re performed with particles and thus the description using a macroscopic w
 ave function fails to predict certain measureable observables. Furthermore
  accessing this regime opens up the route for the generation of entangleme
 nt which can be employed for improving atom interferometry beyond the clas
 sical shot noise limit. \n\n \n\n[1] Nobel laureate Eric Cornell pointed o
 ut: “The overall picture [of BEC theory of an ideal gas] is sufficiently
  easy to understand that\, if the system truly were an ideal gas\, there w
 ould be little left to study at this point”  \n\n
LOCATION:RutherfordEP Seminar Room (980) Rutherford Building\, Cavendish L
 aboratory
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