Studies of Electron Spin in Gallium Arsenide Quantum Dots
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Studies of Electron Spin in Gallium Arsenide Quantum Dots Daniel Craft, Dr. John Colton, Tyler Park, Phil White, Brigham Young University
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Studies of Electron Spin in Gallium Arsenide Quantum Dots. Daniel Craft, Dr. John Colton, Tyler Park, Phil White, Brigham Young University. Quantum Computing. Quantum states are the “1”s and “0”s of a classical computer Certain tasks—like factoring large numbers—are exponentially faster - PowerPoint PPT Presentation
Transcript of Studies of Electron Spin in Gallium Arsenide Quantum Dots
Studies of Electron Spin in Gallium Arsenide Quantum
DotsDaniel Craft, Dr. John Colton,
Tyler Park, Phil White, Brigham Young University
Quantum Computing Quantum states are
the “1”s and “0”s of a classical computer
Certain tasks—like factoring large numbers—are exponentially faster
Must understand quantum states
Jun Li et al, Sci. Rep. 2012/02/10 online
Quantum Dots Tiny, energetically and spatially
constrained structures: 2-10 nm
Quantum computers with interacting quantum dots that have an extra electron
Fast, optical control
Evidence of long lifetimes relative to control
Zeeman Splitting and Electron Spin
% Pol=%Low-% High
Faraday Effect Linearly polarized
light rotates Must be parallel
with magnetic polarization of sample
More magnetic polarization means more rotation
Wikipedia: Faraday Effect
Power Stabilizer
B
Probe-942nm
AOM
Linear Polarizer
Photoelastic Modulator
Signal to Lockin amplifier
Chopper
SuperconductingMagnet Set-up
PolarizingBeam Splitter
BalancedDetector
Timing Sequence
Beginning of Period End of Period
Time
Pump Pulse
Probe Probe Probe Probe Probe Probe Probe Probe Probe Probe Probe
0 500 1000 1500 2000 2500
-0.040-0.035-0.030-0.025-0.020-0.015-0.010-0.0050.0000.0050.0100.0150.0200.0250.0300.0350.0400.045
Lock
in S
igna
l
Time (ns)
T1 Decay Scan?
Probe out of pump
0 500 1000 1500 2000 2500-0.014
-0.012
-0.010
-0.008
-0.006
-0.004
-0.002
0.000
0.002
0.004
0.006
0.008
0.010
0.012
0.014
0.016
-0.04
-0.03
-0.02
-0.01
0.00
0.01
0.02
0.03
0.04
Blu
e
Bla
ck
Time (ns)
Magnetic Field Comparison
bk: 0 Tbl: 1 T
0 500 1000 1500 2000 2500-0.006
-0.004
-0.002
0.000
0.002
0.004
0.006
0.008
0.010
-0.04
-0.03
-0.02
-0.01
0.00
0.01
0.02
0.03
0.04
Blu
e
Bla
ck
Time (ns)
Temperature Comparison
bk: 10 Kbl: 5 K
Power Stabilizer
B
942 nm
AOM
Linear Polarizer
PEM
Signal to Lock-in Amplifier
Chopper
Sample
Electromagnet Set-up
BalancedDetectorPolarizing
Beam Splitter
Electromagnet Scan Goals Same oscillations?
Does frequency change with laser power?
Does it change with pump pulse width?
Conclusions Quantum computing potential
depends on understanding quantum dots
We measure spin lifetimes using the Faraday effect
We saw oscillating spin polarization instead of decay
We need to do further tests
