1. QUANTUM INFORMATION: FUTURE OF MICROELECTRONICS?
PAWEL HAWRYLAK
QUANTUM THEORY GROUP
INSTITUTE FOR MICROSTRUCTURAL SCIENCES
NATIONAL RESEARCH COUNCIL OF CANADA
OTTAWA, K1AOR6,CANADA
CANADIAN INSTITUTE FOR ADVANCED RESEARCH
NANOELECTRONICS AND PHOTONICS PROGRAMME
Self Assembled molecules on a silicon surface. From Dan Wayner’s Research
I’m here to present to you this morning on a field in research and development that nations around the world are recognizing as the arrival of a new scientific era. It is a field based on research discoveries at the atomic and molecular levels. Nanotechnology.

2. WHY QUANTUM INFORMATION: FUTURE OF MICROELECTRONICS?
CMOS IS A MARVEL
OF TECHNOLOGY
YET WITH EXISTING TECHNOLOGY MANY PROBLEMS ARE LIKELY TO REMAIN UNSOLVED:
QUANTUM MATERIALS
NANOSCIENCE-MULTISCALE PROBLEMS
DRUG DESIGN AND DISCOVERY
HARD MATHEMATICAL PROBLEMS – FACTORIZATION OF PRIME NUMBERS (SECURITY OF INFORMATION)
HENCE QUANTUM HARDWARE

3. AND QUANTUM INFORMATION
QUANTUM THEORY
AND QUANTUM INFORMATION
QMechanics: EPR, superposition, entanglement, …
Materials Science: Correlations,mesoscopics,…
Condensed Matter
Superfluidity
Superconductivity
Fractional charge FQHE
Mesoscopics, interference
Quantum materials
????????????
Quantum information:
Quantum computing
Quantum cryptography
Quantum imaging
Quantum sorting …

4. AND QUANTUM INFORMATION
QUANTUM THEORY
AND QUANTUM INFORMATION
Quantum register
| > 1
How Many Configurations?
Number of atoms on Earth?
resources
bits

5. AND QUANTUM INFORMATION
Quantum Groups Worldwide
                                                                                                                                                                            
QUANTUM THEORY
AND QUANTUM INFORMATION
abacus – 500 AD – 10 additions / min
QUANTUM ABACUS
MADE OF HUNDRED BITS
IS MORE POWERFUL
THAN
CLASSICAL ABACUS
BUILD OF
ALL ATOMS ON EARTH

6. QUANTUM INFORMATION 101 QUANTUM ALGORITHMS
| >
= binary decomposition of number K
Spin configuration=|K>
QUANTUM COMPUTATION
initialize
Time t
Evolve to
final target
state T
Measure
Quantum
Bits,Gates
Algorithm

7. QUANTUM HARDWARE AND INFORMATION
DECOHERENCE
QUANTUM STATES ARE FRAGILE
ERROR CORRECTION IS POSSIBLE
OVERHEAD IS VERY HIGH
SOLUTION:
FEW QUBITS EMBEDDED IN CLASSICAL SYSTEMS
FIRST APPLICATIONS?
QUANTUM CRYPTOGRAPHY
QUANTUM ECONOMICS?
QUANTUM METROLOGY
QUANTUM NMR……

8. QUANTUM INFORMATION APPLICATIONS
FEW QUBITS – EMBEDDED IN CLASSICAL SYSTEMS
FIRST APPLICATIONS?
QUANTUM ECONOMICS
QUANTUM CRYPTOGRAPHY

9. APPLICATIONS - QUANTUM ECONOMICS
Quantum Groups Worldwide
                                                                                                                                                                            
QUANTUM INFORMATION 101
APPLICATIONS - QUANTUM ECONOMICS
HP LABS, PALO ALTO

10. APPLICATIONS - QUANTUM ECONOMICS
Quantum Groups Worldwide
QUANTUM INFORMATION 101
APPLICATIONS - QUANTUM ECONOMICS
WHY QUANTUM GAMES?
BIDDING, CONFLICT
ONLY FEW PLAYERS
HIGH PAY-OFF
OF INTEREST NOT ONLY TO PHYSICISTS
“PRISONER DILEMMA” - COOPERATE “C”
- DEFECT “D”
QUANTUM GAME
REMOVES DILEMMA
OPTIMIZES PAYOFF
Quantum Bidding – 2 Qubits –HP Labs-S.Williams

11. BUILDING FEW QUBITS IN SOLID STATE
Quantum Groups Worldwide
                                                                                                                                                                            
QUANTUM HARDWARE
BUILDING FEW QUBITS IN SOLID STATE
QUANTUM HARDWARE
BUILDING FEW QUBITS IN SOLID STATE
USING MICROELECTRONICS
ELECTRON SPIN
NUCLEAR SPIN –NMR
SUPERCONDUCTIVE QUBITS
ATOM/ION TRAPS
ATOM CHIPS
LINEAR OPTICS
…….
QCOMPUTING WITH QDOTS
Barenco et al. 1995
Brum PH 1997
Loss DiVincenzo 1998

12. NANOSCIENCE WITH SINGLE ELECTRONS IN A FIELD EFFECT TRANSISTOR
TOWARD
ELECTRON SPIN BASED
QUANTUM COMPUTER
IN A FIELD EFFECT TRANSISTOR
QComputing with Qdots:
Brum&Hawrylak ’97
Loss&DiVincenzo ‘98

13. ELECTRON SPIN BASED QUANTUM COMPUTER
Model of QComputer : interacting qubits S
Effective qubit
local field
tunable entanglement J
2D electron gas at
GaAs/AlGaAs
AlGaAs
90 nm
SOURCE
DRAIN
LOCALISING
CONTROLLED NUMBER
OF ELECTRONS 1-100
GaAs

14. SINGLE SPIN TRANSISTOR SINGLE SPIN TRANSISTOR
NANO SPINTRONICS
SINGLE SPIN TRANSISTOR
off on
source
artificial
atom
drain
SINGLE SPIN TRANSISTOR

15. SINGLE SPIN TRANSISTOR
NANO SPINTRONICS
SINGLE SPIN TRANSISTOR
n=2
CURRENT
N=18
ODD NE
ODD NE
N=17
N=16
Sachrajda,Ciorga,PH,..
IMS NRC,PRL’02 B

16. ELECTRON SPIN BASED QUANTUM COMPUTER
Model of QComputer : interacting qubits S
Effective qubit
local field
tunable entanglement J
TUNING TUNELING BARRIER
(5,0)
(6,1)
(7,2)
(9,4)
(0,0)
(1,1)
(1,0)
(0,1) D
IQPC 1 2
L.Kouwenhoven et al, Delft
S.Tarucha et al Tokyo
C.Marcus et al, Harvard
M.Heiblum et al, Weizman
A.Sachrajda,M.Pioro-Ladriere,PH, Ottawa

17. ELECTRON SPIN BASED QUANTUM COMPUTER
TWO QUBITS
Model of QComputer : interacting qubits S
tunable entanglement J
Effective qubit
local field
(1,0)
V2 / V
V1 / V
+0.30
-0.70
-0.75
0.0
(5,0)
(6,1)
(7,2)
(9,4)
(9,5)
(7,3)
(8,4)
(5,1)
(4,0)
(0,1)
(6,2)
(8,5)
(0,0)
(7,4)
(5,2)
(6,3)
(3,0)
(4,1)
(75)
(1,0)
(5,3)
(6,4)
IQPC
(2,0)
(4,2)
(6,5) 1 2
(3,1)
(1,1)
(1,2)
(5,4)
(2,3)
(3,3)
(4,3)
(3,4)
(4,4)
(4,5)
(5,5)
(2,1)
(N1,N2) = (0,0)
1 mm
A.Sachrajda,M.Pioro-Ladriere,PH PRL2003, PRB2005

18. ELECTRON SPIN BASED QUANTUM COMPUTER TWO QUBITS-WHY TUNABLE J?
Model of QComputer : interacting qubits S
tunable entanglement J
Effective qubit
local field
(1,0)
|10>
|01> …. ….
J12=0
J12>0
J12>0
J12=0
t=0
t=T
SPIN SWAPPING
BASIS OF CNOT GATE
Loss,DiVincenzo

19. ELECTRON SPIN BASED QUANTUM COMPUTER COHERENT CODED QUBIT OPERATION
Swapping spins
Rabi oscillations
Quantum Optics
on a chip

20. ELECTRON SPIN BASED QUANTUM COMPUTER THREE QUBITS-TRIPLE QUANTUM DOT
Model of QComputer : interacting qubits S
tunable entanglement J
Effective qubit
local field
(1,0)
(5,0)
(6,1)
(7,2)
-0.375
-0.385
-0.41
-0.39
V5B(V)
V1B(V)
N=3
N=2
(1,1,1)
(0,1,2)
N=4
N=1
V5B(V)
V1B(V)
(0,0,0)
(1,1,0)
(0,1,0)
(0,0,1)
(1,0,0)
(0,1,1)
(1,1,1)
-0.25
-0.30
-0.40 C B A
IQPC 1B 3B 5B 3T S
0.5mm 2B 4B
A.Sachrajda,S.Studenikin,L.Gaudreau,A.Kam,
M.Korkusinski, PH, PRL2006

21. ELECTRON SPIN BASED QUANTUM COMPUTER TRIPLE QUANTUM DOT-CODED QUBIT
Model of QComputer : interacting qubits S
tunable entanglement J
Effective qubit
local B field
CODED QUBIT
M.Korkusinski, PH,SSC2005
S=1/2

22. ELECTRON SPIN BASED QUANTUM COMPUTER PROBLEMS AND CHALLENGES
Model of QComputer : interacting qubits S
tunable entanglement J
Effective qubit
local field
(1,0)
Single spin – Koppens, Kouwehoven et al,Nature2006
Operation - Pioro-Ladriere, Tarucha et al.
Coherent two spin operation, Single coded qubit operation
– Petta,…,Marcus
- Koppens, …,Kouwehoven
Coherent spin manipulation over minutes!
- Greilich,Bayer,…Science 2006

23. ELECTRON SPIN BASED QUANTUM COMPUTER
PROBLEMS AND CHALLENGES - DECOHERENCE
Model of QComputer : interacting qubits S
tunable entanglement J
Effective qubit
local field
(1,0)
DECOHERENCE – NUCLEAR SPINS, SO+PHONONS,IMPURITIES
SOLUTIONS? MATERIALS WITHOUT NUCLEAR SPIN
2-6, CARBON NANOTUBES, GRAPHENE?

24. HUBBARD MODEL A WINDOW ON QUANTUM MATERIALS:
TRIPLE QDOT MOLECULES
SPIN, TOPOLOGY, STATISTICS AND E-E CORRELATIONS
LOCALIZED VS ITINERANT ELECTRONS
HUBBARD MODEL
A WINDOW ON QUANTUM MATERIALS:
COMPLEX OXIDES WITH
TRIANGULAR LATTICE
NaxCO2

25. SPIN, TOPOLOGY, STATISTICS AND E-E CORRELATIONS
TRIPLE QDOT MOLECULES
SPIN, TOPOLOGY, STATISTICS AND E-E CORRELATIONS 2 1 2 1
S=0
S=1
Exchange Vx
D~Vx~e^2
triplet
singlet 2 1
Singlet – double occupancy
Super-Exchange
D~4t^2/U~1/e^2
S=0
S=1 t

26. SPIN, TOPOLOGY, STATISTICS AND E-E CORRELATIONS
TRIPLE QDOT MOLECULES
SPIN, TOPOLOGY, STATISTICS AND E-E CORRELATIONS 3 2 1 3 2 1 3 2 1
triplet
singlet
PH,
Korkusinski,
SSC2005
S=1
SINGLET GS!
TOPOLOGICAL “HUNDS” RULE!
SPIN-CHARGE SEPARATION?
S=0
D~t

27. FILLING LOWEST ELECTRONIC SHELL
TRIPLE QDOT MOLECULES
FILLING LOWEST ELECTRONIC SHELL
Korkusinski,Puerto,PH
….. PRB2007 3t 3t
2e SINGLET
4e TRIPLET
-1V
-1.1V
-2.5V 0V 3t 3t
4e SINGLET
Voltage tunable nano-magnet

28. QUANTUM INFORMATION APPLICATIONS
FEW QUBITS – EMBEDDED IN CLASSICAL SYSTEMS
FIRST APPLICATIONS?
QUANTUM CRYPTOGRAPHY –
QUANTUM KEY DISTRIBUTION
SINGLE PHOTONS-SECURE-NO CLONING-
SHORT DISTANCE
ENTANGLED PHOTON PAIRS-
QUANTUM REPEATER-LONG DISTANCE

29. QUANTUM INFORMATION QUANTUM CRYPTOGRAPHY-WHATS NEEDED?
ENABLING TECHNOLOGY
FOR QUANTUM CRYPTOGRAPHY:
SOURCE OF SINGLE PHOTONS ON DEMAND
SOURCE OF ENTANGLED PHOTON PAIRS
ENABLING TECHNOLOGY :
SELF-ASSEMBLED QUANTUM DOT DEVICES

30. QUANTUM INFORMATION QUANTUM CRYPTOGRAPHY
QUANTUM DOT TECHNOLOGY REQUIREMENTS
FOR QUANTUM CRYPTOGRAPHY:
EMISSION AT TELECOM WAVELENGTH
-MATERIALS
ENHANCED LIGHT MATTER INTERACTION
-QDOTS IN PHOTONIC CAVITIES
-PRECISE POSITIONING OF QDOTS
ENGINEERING OF LIGHT POLARIZATION
-FULL UNDERSTANDING OF AND ABILITY TO ENGINEER
OPTICAL PROPERTIES OF QDOT

31. GROWTH AND POSITIONING OF QDOTS EMITTING AT TELECOM WAVELENGTH
STRAIN DRIVEN
SELF-ASSEMBLY: InAs/GaAs
DIRECTED SELF-ASSEMBLY VIA LITHOGRAPHY: InAs/InP at 1.5mm
SiO2
mask
InAs dot
InP pyramid
ARTIFICIAL ATOM FACTORY
Williams,
Poole,…IMS

32. GROWTH AND POSITIONING OF SINGLE QDOTS GATING OF A SINGLE QDOT
M.Reimer,J.Lapointe,P.Poole, R.Williams,…

33. EXTRACTING SINGLE PHOTONS SINGLE QUANTUM DOT IN A CAVITY
Dalacu,Aers,Williams, Poole sa
Q>8000
Tuning
Photon
Field
Inside
cavity
InAs dot
InP pyramid
POSITIONING DOTS IN
E-FIELD MAXIMA

34. ENTANGLED PHOTON PAIRS FROM EXCITON TO
QUANTUM INFORMATION
QUANTUM CRYPTOGRAPHY
ENTANGLED PHOTON PAIRS FROM EXCITON TO
BI-EXCITON CASCADE
Entangled Photon Pairs From a
Semiconductor Quantum Dot,
Akopian, Gershoni, Avron, Petroff,……
PRL 2006
SPLITTING OR

35. QUANTUM CRYPTOGRAPHY-MATERIALS CHALLENGE
QUANTUM INFORMATION
QUANTUM CRYPTOGRAPHY-MATERIALS CHALLENGE
NICE,PROOF OF CONCEPT,
BUT NOT AT
TELECOM WAVELENGTH!
~0.8eV
InAs/GaAs
InAs/InP
(8,5)
Lefebvre,Finnie,IMS

36. TOWARD QUANTUM INFORMATION
WITH QUANTUM DOTS
“Crossing”
(8,5)
InAs dot
InP pyramid