long-lived spin coherence in silicon with electrical readout gavin w morley london centre for...
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Long-lived spin coherence in silicon with electrical readout Gavin W Morley London Centre for Nanotechnology and Department of Physics and Astronomy, UCL. Funding:. Quantum Coherent Properties of Spins II, PITP, 6 th December 2009. Introduction. People Involved in this Work. - PowerPoint PPT PresentationTRANSCRIPT
Funding:
Quantum Coherent Properties of Spins II, PITP, 6th December 2009
People Involved in this Work
University of UtahChristoph BoehmeDane R McCameyHeather A Seipel
National High Magnetic Field LaboratoryHans van TolLouis-Claude Brunel
Introduction
Phosphorus dopants in silicon
- Long spin coherence (A M Tyryshkin et al, PRB 68, 193207 2003)
- Atomic positioning(S R Schofield et al, PRL 91, 136104 2003)
- Control wavefunction size (N Q Vinh et al, PNAS 105, 10649 2008)
Introduction
Introduction
Experimental challenges:
1. Initialization2. Control superposition and entanglement3. Decoherence4. Readout
Introduction Our research
Towards quantum computing
we have a plan
Pulsed ESR at 4, 8 and 12 T
Nuclear Spin Polarization: GWM, J van Tol, A Ardavan, K Porfyrakis, J Zhang and G A D Briggs, Phys Rev Lett 98, 220501 (2007)
CW ESR: J van Tol, L C Brunel and R J Wylde, Rev Sci Inst 76, 074101 (2005)
Introduction Our research
GWM, L-C Brunel and J van Tol, Rev Sci Instrum 79, 064703 (2008)
A
DC current source reacts slowly
Fast current detector measures signal
1 mm overlap
silicon
Circularly polarized 240 GHz radiation manipulates electron spins
Visible light creates electron-hole pairs
B0 = 8.6 T
T = 2.8 K10 micron
Introduction Our research
Continuous-wave electrically-detected magnetic resonance
8.56 8.57 8.58 8.59
-1.5
-1.0
-0.5
0.0
I/I
(%)
Magnetic Field (T)
Our papers: PRL 101, 207602 (2008),
PRL 102, 027601 (2009), PRB 78, 045303 (2008)
Introduction Our research
A
DC current source reacts slowly
Fast current detector measures signal
1 mm overlap
silicon
Circularly polarized 240 GHz radiation manipulates electron spins
Visible light creates electron-hole pairs
10 micron
B0 = 8.6 T
T = 2.8 K
Introduction Our research
e
h
e
h
10 micron
Circularly polarized 240 GHz radiation manipulates electron spins
Visible light creates electron-hole pairs
DD Thornton & A Honig, PRL 30 909 (1973)
A Honig & M Moroz, RSI 49 183 (1978)
GWM, DR McCamey, HA Seipel, LC Brunel, J van Tol & C. Boehme, PRL 101, 207602,(2008)
e
B0 = 8.6 T
T = 2.8 K
Sensitivity: need (100 nm)3 sample
Introduction Our research
Continuous-wave electrically-detected magnetic resonance
8.56 8.57 8.58 8.59
-1.5
-1.0
-0.5
0.0
I/I
(%)
Magnetic Field (T)
Our papers: PRL 101, 207602 (2008),
PRL 102, 027601 (2009), PRB 78, 045303 (2008)
Introduction Our research
Continuous-wave electrically-detected magnetic resonance
8.56 8.57 8.58 8.59
mI = -1/2
I
Magnetic Field (T)
mI = +1/2
Temperature = 1.37 K
Polarization = -68±1 %
Our papers: PRL 101, 207602 (2008),
PRL 102, 027601 (2009), PRB 78, 045303 (2008)
Introduction Our research
DR McCamey, J van Tol, GWM & C. Boehme, PRL 102, 027601 (2009)
Continuous-wave electrically-detected magnetic resonance
1. Thermal Equilibrium
2. Flip-flop, X
3. Capture-emission, CE
1. Thermal Equilibrium
2. Flip-flop, X
1. Thermal Equilibrium
P = 0P < 0
Our papers: PRL 101, 207602 (2008),
PRL 102, 027601 (2009), PRB 78, 045303 (2008)
Introduction Our research
DR McCamey, J van Tol, GWM & C. Boehme, PRL 102, 027601 (2009)
Continuous-wave electrically-detected magnetic resonance
8.56 8.57 8.58 8.59
-1.5
-1.0
-0.5
0.0
I/I
(%)
Magnetic Field (T)
Our papers: PRL 101, 207602 (2008),
PRL 102, 027601 (2009), PRB 78, 045303 (2008)
Introduction Our research
Transient response to a 240 GHz pulse
-10 0 10 20
-1.2
-1.0
-0.8
-0.6
-0.4
-0.2
0.0
0.2
time
current measurement
GWM, DR McCamey, HA Seipel, LC Brunel, J van Tol & C. Boehme, PRL 101, 207602 (2008)
Introduction Our research
Rabi Oscillations
GWM, DR McCamey, HA Seipel, LC Brunel, J van Tol & C. Boehme, PRL 101, 207602 (2008)
Introduction Our research
Isidor Isaac Rabi (1898 – 1988)
time
integrated current measurement
Rabi Oscillations
GWM, DR McCamey, HA Seipel, LC Brunel, J van Tol & C. Boehme, PRL 101, 207602 (2008)
Introduction Our research
time
integrated current measurement
Spin echo animation by Chris Noble
Spin echo
GWM, DR McCamey, HA Seipel, LC Brunel, J van Tol & C. Boehme, PRL 101, 207602 (2008)
Introduction Our research
Erwin L Hahn (born 1921)
Electrically-detected spin echo
0 1 2 3 4 5 6
0
1
2
3
4
5
2 s 2 stime
integrated current
measurement
22
22
2222
GWM, DR McCamey, HA Seipel, LC Brunel, J van Tol & C. Boehme, PRL 101, 207602 (2008)
Introduction Our research
Decay of electrically-detected spin echoes
0 100 200 300 400
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
’
time
integratedmm - wave
echo
time
integrated current
measurement2
22
integrated electrically-
detected echo
2
GWM, DR McCamey, HA Seipel, LC Brunel, J van Tol & C. Boehme, PRL 101, 207602 (2008)
Introduction Our research
Decay of electrically-detected spin echoes
0 100 200 300 400
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
’
time
integratedmm - wave
echo
time
integrated current
measurement2
22
integrated electrically-
detected echo
2
GWM, DR McCamey, HA Seipel, LC Brunel, J van Tol & C. Boehme, PRL 101, 207602 (2008)
Introduction Our research
Decay of electrically-detected spin echoes
GWM, DR McCamey, HA Seipel, LC Brunel, J van Tol & C. Boehme, PRL 101, 207602 (2008)
Introduction Our research
Entangling multiple qubits: theoryA M Stoneham, A J Fisher & P T Greenland, J Phys CM 15 L477 (2003)
R Rodriquez, A J Fisher, P T Greenland & A M Stoneham, J Phys CM 16 2757 (2004)
A M Stoneham, A H Harker & GWM, in press at J Phys CM, arXiv:0904.4895
Qubit 1 Qubit 2Control
light
Introduction Our research
Entangling multiple qubitsBismuth is a good as phosphorus
5 10 15 20 25 30 35 40 45 501E-5
1E-4
1E-3
0.01
0.1
1
10
100
1000
4 x 1016 Bi cm-3 (ref 25) : T1
28Si:P (ref 9): T1
T2
Rel
axat
ion
time
(ms)
Temperature (K)
Our data for ~3 x 1015 Bi cm-3 Monoexponential T
2
T2 from fit to exp(-/T
2-3/T3
S)
TS from fit to exp(-/T
2-3/T3
S)
CPMG decay T
1
Fit to T1
Introduction Our research
Conclusions
Experimental challenges:
1. Initialization2. Control superposition and entanglement3. Decoherence4. Readout
Introduction Our research Conclusions and future work
we have a plan