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Spin transport through a single quantum dot with ferromagnetic - - PowerPoint PPT Presentation
Spin transport through a single quantum dot with ferromagnetic - - PowerPoint PPT Presentation
Spin transport through a single quantum dot with ferromagnetic electrodes & coherent control of nuclear spins in quantum Hall systems IIS and INQIE, Univ. of Tokyo JST CREST Tomoki Machida JST - DFG Workshop on Nanoelectronics 2008.3.5
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Collaborators
Spin transport in a single quantum dot spin valve device
- K. Hamaya, M. Kitabatake (IIS)
- M. Jung, K. Shibata, K. Hirakawa (IIS)
- S. Ishida, Y. Arakawa (RCAST)
Coherent control of nuclear spins in a quantum Hall device
- H. Takahashi, M. Kawamura (IIS)
- Y. Hashimoto, S. Katsumoto (ISSP)
SLIDE 4
Control of spin transport in semiconductor
- S. Datta and B. Das, APL 56, 665 (1990).
- J. Schliemann et al., PRL 90, 146801 (2003).
- cf. Carbon nanotube channel: S. Sahoo et al., Nature phys. 1, 99 (2005).
Spin injection Spin detection Spin manipulation
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Quantum dot + Ferromagnetic leads
Semiconductor quantum dot FM FM A single semiconductor QD with ferromagnetic leads Spin injection, manipulation, detection Spin injection Spin manipulation Spin detection
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Lateral double barrier magnetic tunnel junction
InAs dot VSD VG A
Ni
B
GaAs n+-GaAs AlGaAs
150 nm
Self-assembled InAs QDs
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Tunneling magnetoresistance (TMR)
B R RAP RP
Parallel Parallel Anti-parallel Anti-parallel P P AP
R R R − = TMR
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TK T << N: odd Kondo singlet
N = 3
Coulomb diamond
Kondo effect in a quantum dot
Kondo peak
VSD G
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Outline
Spin transport in a single quantum dot spin valve device Ni/InAs quantum dot/Ni magnetic tunnel junction Spin injection and tunneling magnet resistance (TMR) Gate control of spin transport Oscillatory changes in TMR Kondo effect Coherent control of nuclear spins in a quantum Hall device QHE breakdown Rabi oscillations
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NMR quantum computation (liquid)
- L. M. K. Vandersypen et al.
Nature 414, 883 (2001) C F C F C Fe CO CO C5H5 C F F F
Shor's quantum algorithm 7 qubits
Nuclei Electron Bext
1
NMR
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All-silicon QC (
29Si)
- B. E. Kane, Nature 393, 133 (1998)
Si-based QC (
31P )
- T. D. Ladd et al. ,PRL 89, 017901 (2002)
NMR quantum computation (solid)
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Coherent control of nuclear spins in semiconductor
Quantum Hall edge states
- T. Machida et al.
APL (2003)
Quantum dot
- K. Ono et al.
PRL (2004)
FQHE
- G. Yusa et al.
Nature (2005)
QHE breakdown
- H. Takahashi et al.
APL (2007)
Standard NMR
Optical
Sanada et al. PRL (2006)
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Quantum Hall devices
Al0.3Ga0.7As/GaAs single heterostructure Carrier density: n = 1.6×1015 m-2 Mobility: μ = 220 m2/Vs Temperature: 50 mK
Bext
5 μm
metal strip (local coil)
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Coherent control of nuclear spins
1
Bext RF t
t = A0 0 + A
11
|A0|2 |A1|2
Pulsed -NMR Record Vxx ①Initialization ②Manipulation ③Read out QHE breakdown time Vxx rf-pulse
τpulse
ΔVxx
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Summary
Spin transport in a single quantum dot spin valve device Spin injection and tunneling magnet resistance (TMR) Gate control of spin transport Oscillatory changes in TMR Kondo effect Coherent control of nuclear spins in a quantum Hall device QHE breakdown Rabi oscillations
- K. Hamaya, T. M et al., APL 90, 053108 (2007).
- K. Hamaya, T. M et al., APL 91, 022107 (2007).
- K. Hamaya, T. M et al., APL 91, 232105 (2007).
- K. Hamaya, T. M et al., PRB 77, 081302 (2008).
- M. Kawamura, T. M et al., APL 90, 022102 (2007).
- H. Takahashi, T. M et al., APL 91, 092120 (2007).
- M. Kawamura, T. M et al., JPSJ 77, 023710 (2008).