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UID:1-519@lptms.universite-paris-saclay.fr
DTSTART:20170628T140000Z
DTEND:20170628T170000Z
DTSTAMP:20170502T101714Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/soutenance-de-the
 se-aleksey-fedorov/
SUMMARY:Soutenance de thèse : Aleksey Fedorov - IPN-batiment 100\, Auditor
 iurm - 28 Juin 17 14:00
DESCRIPTION:Non-conventional many-body phases in ultracold dipolar systems\
 nAleksey Fedorov\nThe problem of revealing and describing novel macroscopi
 c quantum states characterized by exotic and non-conventional properties h
 as the fundamental importance for modern physics. Such states offer fascin
 ating prospects for potential applications in quantum information processi
 ng\, quantum simulation\, and material research. In the present Thesis we 
 develop a theory for describing non-conventional phases of ultracold dipol
 ar gases. The related systems of large-spin atoms\, polar molecules\, and 
 dipolar excitons in semiconductors are actively studied in experiments. We
  put the main emphasis on revealing the role of the long-range character o
 f the dipole-dipole interaction. We consider the effect of rotonization fo
 r a 2D weakly interacting gas of tilted dipolar bosons in a homogeneous la
 yer\, and demonstrate that in contrast to the case of perpendicular dipole
 s\, in a wide range of tilting angles the condensate depletion remains sma
 ll even when the roton minimum is extremely close to zero. We predict the 
 effect of rotonization for a weakly correlated Bose gas of dipolar exciton
 s in a semiconductor layer and calculate the stability diagram. According 
 to our estimates\, the threshold of the roton instability for a bose-conde
 nsed exciton gas with the roton-maxon spectrum is achievable experimentall
 y in semiconductor layers. We then consider p-wave superfluids of identica
 l fermions in 2D lattices. The optical lattice potential manifests itself 
 in an interplay between an increase in the density of states on the Fermi 
 surface and the modification of the fermion-fermion interaction (scat- ter
 ing) amplitude. The density of states is enhanced due to an increase of th
 e effective mass of atoms. For short-range interacting atoms in deep latti
 ces the scattering amplitude is strongly reduced compared to free space du
 e to a small overlap of wavefunctions of fermions sitting in the neighbori
 ng lattice sites\, which suppresses the p-wave superfluidity. However\, we
  show that for a moderate lattice depth there is still a possibility to cr
 eate p-wave superfluids with sizable transition temperatures. For fermioni
 c polar molecules\, due to a long-range character of the dipole-dipole int
 eraction the effect of the suppression of the scattering amplitude is abse
 nt. It is shown that for microwave-dressed polar molecules a stable topolo
 gical p+ip superfluid may emerge in the 2D lattice at realistic temperatur
 es. Finally\, we discuss another interesting novel superfluid of fermionic
  polar molecules. It is expected in a bilayer system\, where dipoles are o
 riented perpendicularly to the layers and in opposite directions in differ
 ent layers. We demonstrate the emergence of interlayer superfluid pairing.
  In contrast to the already known s-wave interlayer superfluid\, when all 
 dipoles are parallel to each other\, in our case the s-wave pairing is sup
 pressed and there can be p-wave or higher partial wave superfluids.\nDirec
 teurs de thèse: Georgy Shlyapnikov\nJury: Christophe Texier\, Mikhail Bar
 anov\, Paolo Pedri\, Andrey Varlamov
CATEGORIES:seminars
LOCATION:IPN-batiment 100\, Auditoriurm\, 15 Rue Georges Clemenceau\, orsay
 \, France
GEO:48.698196;2.181773
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=15 Rue Georges Clemenceau\,
  orsay\, France;X-APPLE-RADIUS=100;X-TITLE=IPN-batiment 100\, Auditoriurm:
 geo:48.698196,2.181773
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