Spin (in)coherence of phosphorous donor electron qubits near the … · 2009. 12. 6. · Kapil...
Transcript of Spin (in)coherence of phosphorous donor electron qubits near the … · 2009. 12. 6. · Kapil...
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Spin (in)coherence of phosphorous donor electron qubits near the c-Si/SiO2 interface
Christoph Boehme
Department of Physics University of Utah
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S i ill l i i l i l i ili b d l i
Silicon based quantum electronicsSPIN DEVICES BASED ON CRYSTALLINE SILICON
Spin will play an increasingly important role in (silicon based) electronics
electronic transition controlled by
allowedelectronic
forbiddenelectronic
Quantum Information Processing
controlled by coherent spin state
electronictransition
electronictransition
Electron spin T2 time of 31P donorElectron spin T2 time of 31P donor 22 12
* John J. MORTON Alexei M. TYRYSHKIN et al. Nature, vol. 455, 1085 (2008)
*A. M. TYRYSHKIN et al. PHYSICAL REVIEW B 68, 193207 (2003)
Electron spin T2 time of P donor> 600ms (electron spin) *Electron spin T2 time of P donor> 600ms (electron spin) * 10
2 S 0
2 ST 21
S
B. E. Kane, Nature 393, 133 (1998)
, , ( )
How does the readout of 31P qubit work? SPIN – SELECTION RULES!
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PHOSPHOROUS SPIN READOUT AT THE SILICONDIOXIDE INTERFACE
The c-Si (111)/SiO2 interface
31P SPIN READOUT USING SPIN SELECTION RULESSPIN-SELECTION RULES
A. R. Stegner et al. Nature Physics (2006)D. R. McCamey et al. Appl. Phys. Lett. (2006)
P.M. Lenahan, J. K. Conley, J. Vac. Sci. Technol. B (1998)
A. R. Stegner, C. Boehme et al. Nature Physics 2, 835 (2006).
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OBSERVATION OF THE PHOSPHOROUS – INTERFACE DEFECT TRANSITION
timeESR
puls
e ,, 1B
lase
r
time
timeprr
ent
rent
BQQPP
cur
time
µs-time scalecur ,, 1BQQ
31PPb
31PPb
2 SQ
T
A. R. Stegner, C. Boehme et al. Nature Physics 2, 835 (2006).
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ELECTRICAL DETECTION OF 31P DONOR STATES
T = 5K
(r = 0)|2 HFS = 4.2 mT a‐3
31P
B0
A. R. Stegner, C. Boehme et al. Nature Physics 2, 835 (2006).
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ELECTRICAL DETECTION OF 31P DONOR STATES
T = 5K
A. R. Stegner, C. Boehme et al. Nature Physics 2, 835 (2006).
Seoyoung Paik et al.arXiv:0905.0416v1 (2009)
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ELECTRICAL DETECTION OF 31P DONOR STATES
T = 5K
2
A. R. Stegner, C. Boehme et al. Nature Physics 2, 835 (2006).
Seoyoung Paik et al.arXiv:0905.0416v1 (2009)
2 SQ ?
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T 5K
ELECTRICAL DETECTION OF 31P DONOR STATES
T = 5K
A. R. Stegner, C. Boehme et al. Nature Physics 2, 835 (2006).
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ELECTRICAL DETECTION OF 31P DONOR STATES
T = 5K
Weakly coupled 31P‐Pb spin pairs
A. R. Stegner, C. Boehme et al. Nature Physics 2, 835 (2006).
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ELECTRICALLY DETECTED HAHN-ECHOES OF NEAR INTERFACE 31P
z
ττ τττ τdephasing time τ
x
Increase dephasing time τIncrease dephasing time τ Echo intensity decaysEcho intensity decays Decay time : T coherence timeDecay time : T coherence timeIncrease dephasing time τ Echo intensity decays Decay time : T coherence time
H. Huebl, et al., Phys. Rev. Lett. 100, 177602 (2008).
Increase dephasing time τIncrease dephasing time τ Echo intensity decaysEcho intensity decays Decay time : T2 coherence timeDecay time : T2 coherence timeIncrease dephasing time τ Echo intensity decays Decay time : T2 coherence time
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ELECTRICALLY MEASURED T2 RELAXATION
1μs at 10K1μs at 10K1μs at 10KEcho decayEcho decay Temperature dependenceTemperature dependence
==
80μs80μs80μs
• T2 time at interface is const. at different temperatures.• T2 time at interface is const. at different temperatures.T2 time at interface is const. at different temperatures. • ESR T2 has temperature dependence : T1 limits T2 in the ESR measurement.*• T2 time at interface is much shorter than in bulk T2 at low temperature.
T2 time at interface is const. at different temperatures. • ESR T2 has temperature dependence : T1 limits T2 in the ESR measurement.*• T2 time at interface is much shorter than in bulk T2 at low temperature.
S. –Y. Paik, S.-Y. Lee, D. R. McCamey, C. Boehme, arXiv: 0905.0416 (2009).
* A. M. Tyryshkin et al. PHYSICAL REVIEW B 68, 193207 (2003)* A. M. Tyryshkin et al. PHYSICAL REVIEW B 68, 193207 (2003)
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ELECTRICALLY DETECTED INVERSION RECOVERY EXPERIMENT
IS SPIN RELAXATION TIME TRULY LIMITED BY ELECTRONIC TRANSITION OR IS FIELD TRANSITION OR IS FIELD FLUCTUATIONS AT INTERFACE ?
R. de Sousa, Phys. Rev. B 76, 245306 (2007).
T1 = 4.0(5)sT2 = 1.3(8)s at low HF -31P peakT2 = 2 1(7)s at high HF -31P peak
S. –Y. Paik, S.-Y. Lee, D. R. McCamey, C. Boehme, arXiv: 0905.0416 (2009).
T2 = 2.1(7)s at high HF - P peak
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ELECTRICALLY T1 RELAXATION AT LOWER INTERFACE STATE DENSITIES
S. –Y. Paik, S.-Y. Lee, D. R. McCamey, C. Boehme, arXiv: 0905.0416 (2009).
c-Si/SiO2 INTERFACE WITH 4 TIMES SMALLER INTERFACE DENSITY
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RELAXATION TIMES OF NEAR INTERFACE PHOSPHOROUS DONOR STATES
CONCLUSIONS
• EDMR T1, T2 times are much shorter than ESR T time• EDMR T1, T2 times are much shorter than ESR T time
CONCLUSIONS
shorter than ESR T2 time.
• electronic transition time
shorter than ESR T2 time.
• electronic transition time probably limits T1 relaxation time.
• Incoherence time T2 of 31P qubit
probably limits T1 relaxation time.
• Incoherence time T2 of 31P qubit 2 qis shortened due to the interface states.
2 qis shortened due to the interface states.
Silicon‐based QCs using 31P qubits (AND READOUT) need Silicon‐based QCs using 31P qubits (AND READOUT) need
S. –Y. Paik, S.-Y. Lee, D. R. McCamey, C. Boehme, arXiv: 0905.0416 (2009).
Q g q ( )to overcome the limitation imposed by interface defects
Q g q ( )to overcome the limitation imposed by interface defects
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SPIN-DEPENDENT TRAPPING AT BULK PHOSPHOROUS IN SILICON
• SPIN TRAPPING
- D. D. Thornton, A. Honig, Phys. Rev. Lett. (1973)
ESR ELECTRON CAPTURE
ELECTRON EMISSION
Quasi‐optical Superheterodyne EPR System
SPIN-TRAPPING IS ONLY VISIBLE WHEN ELECTRONS ARE STRONGLY POLARIZED –
AT VERY HIGH MAGNETIC FIELDSAT VERY HIGH MAGNETIC FIELDS
J. van Tol et al., Rev. Sci. Instrum. 76, 074101 (2005).
SEE GAVIN MORLEYs TALK THAT WILL COME NEXT
G. W. Morley, D. R. McCamey, H. A. Seipel, L. C. Brunel, J. van Tol & C. Boehme. Phys. Rev. Lett. 101, 207602 (2008).
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Questions?
Christoph Boehme
Department of Physics University of Utah
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The University of Utah Spin Electronics group
David Waters, William Baker grumpy looking guy
Kapil Ambal, Seo-Young Paik Sang-Yun Lee
Janvida Rou, Dane McCamey