Sensing & Controlling Single Spins in Silicon Andrew Dzurak University of New South Wales [email protected]
ANFF – AFOSR Program Review Washington D.C., 30 April - 4 May 2012 ANFF @ UNSW
• 3 x EBL Systems (Raith, FEI ...) • Highest Concentration in Australia • Sub-10nm Features • Silicon MOS Process Line
TiAuPd ANFF-NSW: Key Research Areas
Silicon Nanoelectronics Silicon Photovoltaics Biomedical Devices (eg. Bionics, Si Biosensors) Telecomms (Nano-photonics) Quantum Information Technologies www.anff.org.au Conventional computing …
… must confront some serious issues
Cost of Fab $60B
$50B
$40B
360B
$20B
? $10B
$0B 1992 1995 1998 2001 2004 2007 2010 Year Quantum computing
… could well be the solution Conventional Quantum |1> Computer Computer
0 , 1 |0 >, |1 > |0>
bits qubits
Quantum state of a two-level system |0> |1> Quantum Information Science
Data Security Decryption
National Security National Security Financial Services Intelligence e-Commerce Killer? Apps High Performance Semiconductors Computing Database Searching Integrated Circuits Bioinformatics Sensors Modeling & Design Nano-structuring Code Decryption
• Public key encryption (RSA-129) is (almost) uncrackable. Basis of public secure comms today • A full-scale (few hundred qubits) quantum computer could crack RSA-129 in seconds (Peter Shor – 1994) • Obvious applications in national and global security High Performance Computing
• Simulation (modeling) & database searching • Existing supercomputers now under strain • Application areas: Nuclear weapons simulation Rapid data search – Security services Biotechnology – modeling (new reagents & pharma) – – searching (bioinformatics) Advanced R&D – modeling (commercial, govt) Internet Search Engines – q-Google ? • Timescale for 1 0 0 0 qubits: 1 0 – 3 0 years Next Generation Integrated Circuits
• Spin-off or pathway technologies potentially provide nearer term applications than QC per se • Eg: Single atom nanotechnologies • Possible applications: Next generation transistors - extending Moore’s Law (to 2020)
- single atom transistors Transistors per chip 109 ? 108
• Current world semiconductor Pentium 80786 7 10 Pro 80486 market $ 2 0 0 billion Pentium 106 80386 80286 105 8086
104 8080 4004 103 1970 1975 1980 1985 1990 1995 2000 2005 2010 Year The first quantum computers … Spin-based Qubits: GaAs Quantum Dots GaAs Spin Qubits: David Reilly (U. Sydney)
• US-EU-JAPAN-AUST collaboration: Multi-qubit operations with electron spins Funded by US iARPA Spin Qubits in Silicon
• ARC Centre of Excellence for Quantum Computation & Communication Technologies (CQCCT) A$24.5M for 2011-17
B=2T
Phosphorus Donor Spin Qubits in Silicon
• Long Coherence Times in Silicon at 1K: Nuclear – mins Electron – ms-s • Scalable • Industry “Compatible”
Transport
Interaction
B=2T
Hollenberg et al, PRB (2006) Single Atom Nanotechnologies: Top-Down & Bottom-Up
1 nm Single Atom Nanoelectronics : Top Down
UNSW U Melbourne D.N. Jamieson et al. Summary SPIN QUBITS IN SILICON
• 31P Electron Spin Qubit Single-Shot Readout Single Electron ESR
• 31P Nuclear Spin Qubit Single-Shot Readout Single Atom NMR
• Next Steps ... Co-Workers, CQC2T Programs & Sponsors Integrated Silicon Nano-Spintronics: ASD Quantum Spin Control: Andrea Morello Deterministic Atom Implant: David Jamieson UNSW University of Melbourne Jarryd Pla Jessica van Donkelaar, Juan-Pablo Dehollain Dr Changyi Yang, Andrew Alves, Jeff McCallum, Lloyd Hollenberg Rachpon Kalra Fahd Mohiyaddin Dr John Morton, Oxford Henry Yang Malcolm Carroll, Rajib Rahman ... Sandia Jason Cheng Gerhard Klimeck, Purdue Chandni Ravi Dr Nai Shyan Lai Dr Mikko Möttönen, Dr Kuan Yen Tan, Dr Kok Wai Chan Aalto, Finland Dr Fay Hudson Dr Wee Han Lim, NUS Dr Arne Laucht Dr Floris Zwanenburg, Twente Summary SPIN QUBIT READOUT
• 31P Electron Spin Qubit High-Fidelity (>90%) Single-Shot Readout
Electron Spin T1e ~ 6 s A. Morello et al., Nature 467, 687 (2010) Readout Device: Si-MOS SET
S. Angus, A.J. Ferguson, A.S. Dzurak & S. Angus, A.J. Ferguson, A.S. Dzurak & R.G. Clark, R.G. Clark, Nano Lett. (2007) Appl. Phys. Lett. (2008) Spin Readout Device for P donors
3 donors in the 3050 nm “active area” 18 in total
P-donor & SET Island are Tunnel-Coupled
A. Morello et al., Phys. Rev. B 80, 081307(R) (2009)
TEM Device Fabrication
n++ n++ Al
source Al AlxOy top gate SiO 20 nm 2 Silicon 100 nm plunger
10 mm drain n++ n++ Spin-to-Charge Conversion
donor
reservoir & SET island drain
B
Vtop gate
Vplunger Charge Sensing: 100% Contrast
ISET
donor
N-1 N N+1
Electron on P-donor ISET = 0 (Coulomb blockade)
P-donor Empty ISET > 0
Vtop gate
ISET
Vtop gate
Vplunger Electron Spin Qubit: Readout Protocol
Andrea Morello et al. Phys. Rev. B 80, 081307R (2009)
Hans Huebl et al., Phys. Rev B 81, 235318 (2010)
Andrea Morello et al., Nature 467, 687 (2010) B-Dependence of Spin Lifetime: T1
10
) 1
- Valley (s
repopulation
1 -
1 -1 5
T T1 B
1
Relaxation rate Relaxation T1 6 s 0.1
1 2 3 4 5 6 Magnetic field B (T)
A. Morello et al., Nature 467, 687 (2010) High Fidelity Spin Readout
BW = 120 kHz
Rise/fall time 3 ms
92% Visibility
A. Morello et al., Nature 467, 687 (2010) Summary SPIN QUBIT CONTROL & READOUT • 31P Electron Spin Qubit Single Electron ESR
• 31P Nuclear Spin Qubit Single-Shot Readout Fidelity > 99.9%
Jarryd Pla Juan Dehollain Kuan Yen Tan Wee Han Lim David Jamieson John Morton Andrea Morello Qubit Gate Operations: P-Donor ESR & NMR
1. Qubit Initialize: |
2. Spin Rotation: | + |
Electron spin down NMR and ESR pulses 3. Qubit Readout: initialization electron spin flips conditional to nuclear state | or | Projective single-shot measurement
| | 31P:Si P-Donor B0 RF1 Electron/Nuclear
Bac mw1 mw2 Spin Levels
RF2 = Electron Spin, S | = Nuclear Spin, I |
H = gmBB0Sz – nB0Iz + A I S On-Chip Microwave Line
No Resonator Broadband to 50 GHz On-chip Balun Lithographic transition CPW CPS
Local Spin Resonance + Single-Shot Readout
Single P Donor ESR
load ESR pulse readout B
160
VP V3 120 V2
80 i ESR
Spin-Up Counts Spin-Up 40 I SET
1.610 1.612 1.614 1.616 B (T) time
Local ESR + Single-Shot Readout Single P Donor ESR
load ESR pulse readout B
160
VP V3 120 V2
80 i ESR
Spin-Up Counts Spin-Up 40 I SET
1.610 1.612 1.614 1.616 B (T) time
Local ESR + Single-Shot Readout Single P Donor ESR
load ESR pulse readout B 4.08 mT
160
VP V3 120 V2
80
i ESR Spin-Up Counts Spin-Up Spin-Up Counts Spin-Up 40 I SET
1.610 1.612 1.614 1.616 B (T) time
Local ESR + Single-Shot Readout 31P Nuclear Spin Qubit: Single-Shot Readout
B0 = 1.78986 T
| |
0.3 0.2 mw1 mw2
0.1 Up Fraction Up
- | 0.4 | 0.2
= Electron Spin
Electron Spin Electron 0.0 49.50 49.55 49.60 49.65 = Nuclear Spin µw (GHz) 31P Nuclear Spin Qubit: Single-Shot Readout
Pulse Sequence: B0 = 1.079 T = 29.891 GHz 256 repetitions mw1 260 ms per measurement mw2 = 30.005 GHz read read read read mw2 mw2 mw1 mw1 | |
140
120 mw1 mw2 100
80
|
60 |
40 electron spin-up counts spin-up electron 20
0 0 60 120 180 240 300 360 420 > 7 hours …! Time (min) 31P Nuclear Spin Qubit: Single-Shot Readout
B.E. Kane, Nature read read read read mw2 mw2 mw1 mw1 393, 133 (1998)
B=2T
140 120 | 100 |
80
60 mw1 mw2
40 electron spin-up counts spin-up electron 20 0 | 40 45 50 55 60 | Time (min)
T1n ~ mins (cf. hrs in bulk) 31P Nuclear Spin Qubit: Readout Fidelity
140
120
100
80 Readout Fidelity > 99.9% 60
40 electron spin-up counts spin-up electron 20
0 40 45 50 55 60 Time (min) 0.09 Off-resonance 1.0 On-resonance Off-res. fidelity
0.8 On-res. fidelity
0.06 Visibility 0.6 0.4 0.03
Probability 0.2
0.00 FidelityVisibility / 0.0
0.0 0.2 0.4 0.6 0.0 0.2 0.4 0.6 0.8 1.0 Spin-Up Fraction Spin-Up Fraction Threshold Coherent Control: Electron Spin Qubit – Rabi Oscillations
T ~ 150 ns; -pulse Fidelity = 57% load coherent pulse readout Measurement Fidelity = 79%
180 10 dBm
160
7 dBm VP 140
V3
120
V2 1 dBm Spin-Up Counts Spin-Up
100 tp 0.0 0.5 1.0 1.5 i rabi 4 t (ms) p
3
I SET 2
time Rabi Frequency (MHz) Rabi 1 1 2 3 P1/2 (mW1/2) Coherent Electron Spin Control: Hahn Echo
1.0 Decoherence Mechanisms: 0.8 Spectral Diffusion, 29Si Single P Donor: 0.6 B-Field Fluctuations T2e ~ 200 µs 0.4 Cf. Bulk: 0.2 T2e ~ 240 µs Norm. Echo Intensity Echo Norm. Gordon and Bowers, PRL 1, 368 (1958) 0.0
0.0 0.5 1.0 1.5 Delay (ms) Spectral Diffusion in natSi
28Si,30Si Lattice 29Si o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o 31P o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o 28 T2e > 1 s in Si [A.M. Tyryshkin et al., arXiv:1105.3772] 31P Nuclear Spin Qubit: Single Donor NMR
read read read read RF mw2 RF mw2 RF mw1 RF mw1
80
| | 60 40 RF1 20 h A/2 + B
ifference RF2 n 0 D 0 75.66 75.68 75.7 75.72 75.74 75.76 75.78 75.8 w1
m mw2 80 Count Count
RF2 60
up up - | 40 | hRF1 A/2 – nB0
Spin 20 38.55 38.6 38.65 38.7 NMR Frequency (MHz)
Nuclear gyromagnetic ratio, n = (RF2 - RF1) / 2B0 = 17.2 MHz/T 31 Cf. Bulk NMR value for P nucleus, n = 17.25 MHz/T Electronless NMR
empty empty empty empty load read load load read load RF mw2 RF mw2 RF mw1 RF mw1
Ionized P donor during rf excitation
| 0.3
0.2
RF
0.1
Spin-Up Prob. Difference Prob. Spin-Up 0.0 | 30.2 30.4 30.6 30.8 F (MHz) rf 31P Nuclear Spin Qubit: Rabi Coherent Control
empty load read read read read mw1 RF mw1 mw2 mw2
µW Power = 11 dBm tp 1.0 | 0.5
0.0 µW Power = 5 dBm
RF 1.0 n
P 0.5
| 0.0
1.0 µW Power = -1 dBm Spin Flip Probability, P SpinProbability, Flip 0.5
Rabi Gate Fidelity ~ 99% 0.0 T ~ 30 µs 0 100 200 300 T (ms) p 31P Nuclear Spin Qubit: Hahn Echo
Hahn Echo with Electron OFF T2n ≈ 61 ms
Hahn Echo with Electron ON T2n ≈ 3.8 ms 1.0 31 28 Bulk Value for P: Si (Electron ON)* T2n ≈ 65 ms
CPMG (20 Pulse) with Electron OFF T2n ≈ 200 ms
0.5
Echo Amplitude Echo 0.0
0 60 120 180 240 300 Delay (ms) * J.J.L. Morton et al. Nature 455, 1085 (2008) Summary: Electron & Nuclear Spin Qubits
Electron Spin Qubit
Single-shot readout: 92% fidelity
Spin lifetime: T1 > 6 s 1-qubit gate: 75 ns FID – echo shape: T2* 55 ns Hahn echo: T2 200 ms CPMG: T2 > 600 ms 3 T2 / : 3 x 10
31P Nuclear Spin Qubit 29 Si Nuclear Spin Qubit Single-shot readout: 99.99% fidelity Quantum jumps: T > 2 minutes Single-shot readout: > 90% fidelity 1 1-qubit gate: 30 ms Quantum jumps: T1 ~ mins Rabi & Ramsey: T2* 3.3 ms 1-qubit gate: 100 ms Hahn echo: T2 61 ms Rabi & Ramsey: T2* 2.4 ms CPMG: T2 200 ms Hahn echo: T2 6 ms T / : 2 x 103 2 2 T2 / : ~ 10 Scalable + Fault-tolerant Architecture
Classical CMOS circuitry
Spin transport rails
1- and 2-qubit gates
Spin readout (spincharge conversion) L. Hollenberg et al., PRB 74, 045311 (2006)
Sensing & Controlling Single Spins in Silicon Andrew Dzurak University of New South Wales [email protected]
ANFF – AFOSR Program Review Washington D.C., 30 April - 4 May 2012