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SUMMARY:Anisotropic Dipolar Interactions in Indirect Exciton Bilayers - Pa
 ulo V. Santos\, 
DTSTART:20190923T100000Z
DTEND:20190923T110000Z
UID:TALK130201@talks.cam.ac.uk
CONTACT:Dr Kaveh Delfanazari
DESCRIPTION:The dipolar interaction normally dominates the coupling betwee
 n charge neutral species with a\ndipolar moment. Contrary to the isotropic
  Coulomb interaction\, the dipolar coupling depends not\nonly on the separ
 ation r between the dipoles but also on the angle θ between r and the dip
 ole\nmoment p. In particular\, for collinear dipoles\, the dipolar couplin
 g turns from repulsive for large θ to\nattractive for cos 2 θ &lt\; 1/3.
  This anisotropic character gives rise to interesting phenomena in dipolar
 \nsystems including pattern formation and instabilities in ferrofluids\, l
 iquid crystals\, and Bose-Einstein\ncondensates of dipolar species.[2]\nIn
  this talk\, we demonstrate that the attractive component of the dipolar i
 nteraction can bind\naligned solid-state dipoles consisting of indirect ex
 citons (IX) in two stacked double quantum well\nbilayers.[1] Each bilayer 
 consists of two QWs separated by a thin tunneling barrier. A vertical elec
 tric\nfield applied across the structure drives electrons and holes to dif
 ferent QWs\, thus producing IX with\na dipole moment aligned with the fiel
 d. By using spatially and time-resolved photoluminescence\nspectroscopy\, 
 we show that the presence of a dipolar cloud in one bilayer changes the sp
 atial\ndistribution of IX dipoles in the other bilayer. The changes in spa
 tial distribution are accompanied by\nan increase in the IX binding energy
 \, which are accounted for by a polaron model for the IX-IX\ninteraction. 
 These results demonstrate the feasibility of dipolar control gates using s
 tacked\nstructures and open the way for the realization of interacting dip
 olar lattices in semiconductor\nsystems.\nThis project has received fundin
 g from the German DFG and the German-Israeli Foundation (GIF).\n*santos@pd
 i-berlin.de\nReferences\n[1] Colin Hubert\, Yifat Baruchi\, Yotam Mazuz-Ha
 rpaz\, Kobi Cohen\, Klaus Biermann\, Mikhail\nLemeshko\, Ken West\, Loren 
 Pfeiffer\, Ronen Rapaport\, and Paulo Santos. Attractive dipolar coupling\
 nbetween stacked exciton fluids. Phys. Rev. X\, 9:021026\, May 2019.\n[2] 
 T Lahaye\, C Menotti\, L Santos\, M Lewenstein\, and T Pfau. The physics o
 f dipolar bosonic quantum\ngases. Rep. Prog. Phys.\, 72(12):126401\, 2009.
LOCATION:Mott Seminar Room (531)\, Cavendish Laboratory\, Department of Ph
 ysics
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