Na Young Kim (Stanford, AP)Manuel Aranzana (ENS)

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Center for Quantum Information ROCHESTER HARVARD
CORNELL STANFORD RUTGERS LUCENT TECHNOLOGIES
Quantum Electron Optics and Electron Entanglement
Na Young Kim (Stanford, AP) Manuel Aranzana
(ENS) William D. Oliver (Stanford, EE) Leo Di
Carlo (Harvard) Fumiko Yamaguchi (Stanford,
AP/EE) Gwendal Feve (ENS) Yoshihisa Yamamoto
(Stanford, AP/EE) Jungsang Kim
(Lucent) Robert Liu (UCSF) Jing Kong
(Stanford, Chem) Xavier Maitre (CNRS) Hongjie
Dai (Stanford, Chem)
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Electron Entanglement via a Quantum Dot
Single electron tunneling suppressed by energy
conservation EL ER1
ER2 Two-electron virtual tunneling
is allowed EL1 EL2 ER1 ER2 Only
singlet-state remains at output
indistinguishability and Fermi statistics
including Pauli Exclusion Principle Non-linearity
Coulomb charging energy U Optical
analogy Chi-(3) four-wave mixing process
W. D. Oliver et al., PRL 88, 037901 (2002)
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Noise Suppression in Carbon Nanotubes
Experimental Fano factor (noise suppresion)
SCNT 0.17 (2eI)
Elastic scattering 1-T (transparent contacts)
ST 2eI(1-T) 0.63 (2eI)
Remainder of suppression LL parameter g
S 2eIB 2 (ge) I(1-T) g (1-T) 2eI
g, elastic scattering yield noise suppression
CNT g 0.2 0.3 theory, g 0.28 expt
SCNT g(1-T) 2eI 0.17 (2eI)
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Integrated CNT / SC Structures for Electron
Entanglement
CNT as a quantum dot (0D) structure
Easy to make strong tunnel barriers Strong
confinement w/out surface depletion effect
Very small CNT quantum dot entangler
CNT as a quantum wire (1D) structure
Ideal 1D channel, minimize intermode coupling
Reduced scattering phase space (cf., 2D leads)
interconnect with long mean free path (?)
Caveat LL quasi-particle not free electron (cf.,
Fermi Liquid) collective excitation (CDW,
SDW) TBD how does this effect entanglement ??
CNT as 0D and 1D structure
Kinks, CNT overlap, AFM tip, etc. create tunnel
barrier
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Future Directions
Theory of regulated entangled pair generation
unitary limit of conductance with resonant
biasing .. natural regulation
turnstile-like operation .. engineered
regulation Luttinger Liquid theory
Experimental demonstration of electron entangler
Integrated semiconductor / CNT structure
Bunching / Anti-bunching experiment
Noise Properties of the 0.7 Structure HBT-type
Experiment shows noise suppression one
channel in unitary limit one channel partially
conducting Collision experiment spin
polarized vs. unpolarized
-0.1
0.8
-0.2
0.6
-0.3
Conductance (G/GQ)
Normalized xcov
-0.4
0.4
-0.5
0.2
-0.6
-0.7
-2.9
-2.8
-2.7
-2.6
-2.5
Gate Voltage (V)