ELFT HÍRADÓ

[Csete Maria <mcsete AT physx.u-szeged.hu>]

Meghívó

SZTE TTIK Fizikus Tanszékcsoport Szemináriuma

Eloado: Dr. Domokos Péter, MTA levelezo tagja
Magyar Tudomanyos Akademia,
Wigner Fizikai Kutatóközpont
Szilárdtest-fizikai és Optikai Intézet

Cim:
Bose-Einstein kondenzátum optikai rezonátorban:
a Dicke-féle szuperradiáns kvantumfázisátalakulás felderítése

Idopont: 2013, december 12, 13 h
Helyszin: SZTE TTIK, Budo Agoston tanterem, Szeged, Dom ter 9

Absztrakt: The coherent coupling of a single mode of the resonator with 
motional excitations of a Bose-Einstein condensate driven by a laser 
perpendicular to the cavity axis
was shown to be a formal realization of the Dicke model. This system led to the 
first observation of the phase transition in the Dicke model which is, in fact, 
the zero
temperature limit of the atomic self-organization in a cavity. Beyond the 
mapping of the phase diagram, the spontaneous symmetry breaking as well as the 
mode softening in the
excitations spectrum at the critical point have been demonstrated 
experimentally. The cavity-based realization is an open system, therefore the 
Dicke-type Hamiltonian does
not provide for a complete description. The critical behavior has been 
reinvestigated for the stationary state of the driven and damped system. We 
will show that the
non-equilibrium system exhibits a dynamical quantum phase transition. The 
critical point as well as the mean field solution are only slightly modified 
with respect to the
equilibrium phase transition in the ground state. However, the correlation 
functions describing the quantum fluctuations differ significantly in the 
two, equilibrium and
non-equilibrium, cases. Recent experiments revealed  the importance of the 
atom-atom s-wave scattering in quantitative description of data. Here we will 
show that the damping
of motional excitations is very sensitive to the coupling to a photon field and 
the Beliaev damping rate can be resonantly tuned by the external laser drive 
strength.


Minden erdeklodot szeretettel varunk.

Dr. Csete Maria
szeminarium-koordinator