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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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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
Reference Eisenstein and AHM Nature 432, 691 (2004)
Josephson Qubit Non-linear Non-Dissipative Devoret Walraff & Martinis cond-mat/0411
- e Excitons – Elementary Excitations of Intrinsic Semiconductors Conduction Band e h h Valence Band
Counterflow Superfluidity Electron-Hole Pairs (n’,n)=(,) =Ferromagnetism (n’,n)=(c,v) = Excitonic BECs (n’,n)=(TopLayer,BottomLayer) Order Parameter
GaAs GaAs AlGaAs AlGaAs AlGaAs AlGaAs - - e Ga 100 A 100 A As Si energy Quantum Well Double Quantum Well Quantum Wells
Molecular Beam Epitaxy heated cells Al Ga As Pfeiffer - Bell Labs Shayegan – Princeton ultra high vacuum high quality GaAs substrate
Assemble Bilayer Add magnetic field Particle-hole transformation Electrons and Holes in the QH Regime
voltmeter I I - e voltmeter 0 0 voltmeter voltmeter
Superflow in Electron-Electron Bilayers Hall Angle Not Large σxx 1000 e2/h Kellogg and Eisenstein cond-mat/0401521
Tunneling rate 0 0 Interlayer Voltage Josephson-like Currents
J.J. Dynamics eV = 0 Δ sin(φ) = Ibias Correct Explanation? 0 Josephson Effect
Thin Film Ferromagnet Dynamics Collective Dynamics & Dissipation Ferromagnets vs. Josephson Junctions vs. Bilayers J.J. Dynamics
Joglekar TDHFA+SCBA αφ>> αN Joglekar & AHM PRB (2002)
Thin Film Ferromagnet Dynamics Thin Film Ferromagnets Buhrman & Ralph, MSU, NIST, Orsay Spin Transfer
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
Excitonic Bose Einstein Condensation in Quantum Hall Bilayers ! Macroscopic Quantum Coherence properties different from both JJ’s and thin film magnets