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Excitonic BEC in in Quantum Hall Bilayers

University of Texas at Austin. Excitonic BEC in in Quantum Hall Bilayers. May 2005. Ramin Abolfath NRCC Anton Burkov UCSB Jim Eisenstein Cal Tech. Steve Girvin Yale Yogesh Joglekar LANL Jairo Sinova Texas A&M Ady Stern Weizmann Leo Radzihovsky UC

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Excitonic BEC in in Quantum Hall Bilayers

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  1. University of Texas at Austin Excitonic BEC in in Quantum Hall Bilayers May 2005 Ramin Abolfath NRCC Anton Burkov UCSB Jim Eisenstein Cal Tech. Steve Girvin Yale Yogesh Joglekar LANL Jairo Sinova Texas A&M Ady Stern Weizmann Leo Radzihovsky UC Alvaro Nunez UTA Enrico Rossi UTA Giovanni Vignale UMC

  2. Reference Eisenstein and AHM Nature 432, 691 (2004)

  3. Josephson Qubit Non-linear Non-Dissipative Devoret Walraff & Martinis cond-mat/0411

  4. Landau Liftshitz Gilbert

  5. - e Excitons – Elementary Excitations of Intrinsic Semiconductors Conduction Band e h h Valence Band

  6. Excitonic BEC and Superfluidity?

  7. Counterflow Superfluidity Electron-Hole Pairs (n’,n)=(,) =Ferromagnetism (n’,n)=(c,v) = Excitonic BECs (n’,n)=(TopLayer,BottomLayer) Order Parameter

  8. GaAs GaAs AlGaAs AlGaAs AlGaAs AlGaAs - - e Ga 100 A 100 A As Si energy Quantum Well Double Quantum Well Quantum Wells

  9. Molecular Beam Epitaxy heated cells Al Ga As Pfeiffer - Bell Labs Shayegan – Princeton ultra high vacuum high quality GaAs substrate

  10. Assemble Bilayer Add magnetic field Particle-hole transformation Electrons and Holes in the QH Regime

  11. voltmeter I I - e voltmeter 0 0 voltmeter voltmeter

  12. Electron-hole Pair Current

  13. Superflow in Electron-Electron Bilayers Hall Angle Not Large σxx 1000 e2/h Kellogg and Eisenstein cond-mat/0401521

  14. Tunneling rate 0 0 Interlayer Voltage Josephson-like Currents

  15. J.J. Dynamics eV = 0 Δ sin(φ) = Ibias Correct Explanation? 0 Josephson Effect

  16. Thin Film Ferromagnet Dynamics Collective Dynamics & Dissipation Ferromagnets vs. Josephson Junctions vs. Bilayers J.J. Dynamics

  17. Joglekar TDHFA+SCBA  αφ>> αN Joglekar & AHM PRB (2002)

  18. Thin Film Ferromagnet Dynamics Thin Film Ferromagnets Buhrman & Ralph, MSU, NIST, Orsay Spin Transfer

  19. Empl 10-6 eV ΔQP  10-3 eV G  e2/h Transport Orbitals eV Condensate Orbitals Δt 10-9 eV V* 10-6 Volts K = X l2 Coherent Edge Transport

  20. Excitonic Bose Einstein Condensation in Quantum Hall Bilayers ! Macroscopic Quantum Coherence properties different from both JJ’s and thin film magnets

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