Quantum Dot Spin QuBits

33 Pages·2012·3.64 MB·English

by  Anastasia Varlet

QSIT Student Presentations
Quantum Dot Spin QuBits
Quantum Devices for Information Technology

Anastasia Varlet ETH - 05/04/12
Outline
I. Double Quantum Dot
∣S〉
II. The Logical Qubit
∣↓↑〉 ∣↑↓〉
∣T 〉
0
III. Experiments

Anastasia Varlet ETH - 05/04/12
I. Double Quantum Dot
1. Reminder : Quantum Dot (QD)
AlGaAs/GaAs heterostructure → 2DEG at the interface.
[1] T. Ihn, Semiconductor Nanostructures (2009), Oxford University Press. [2] Hanson et al.,Coherent manipulation of single spins in SC (2008),
Nature 453, 1043

Anastasia Varlet 1/14 ETH - 05/04/12
I. Double Quantum Dot
1. Reminder : Quantum Dot (QD)
S D
Picture from:
[3] Ciorga et al.,
Electrically-defined island → top gates on a 2DEG
Phys. Rev. B 61 (2000)
2 tunable parameters : - source and drain bias
- plunger gate voltage
PG

Anastasia Varlet 2/14 ETH - 05/04/12
I. Double Quantum Dot
1. Reminder : Quantum Dot (QD)
S D
Picture from:
[3] Ciorga et al.,
Electrically-defined island → top gates on a 2DEG
Phys. Rev. B 61 (2000)
2 tunable parameters : - source and drain bias
- plunger gate voltage
PG
[4] Hanson et al., Spins in few-electron QDs (2007), Rev. Mod. Phys., Vol. 79, No. 4
Anastasia Varlet 2/14 ETH - 05/04/12
I. Double Quantum Dot
1. Reminder : Quantum Dot (QD)
S D
Picture from:
[3] Ciorga et al.,
Electrically-defined island → top gates on a 2DEG
Phys. Rev. B 61 (2000)
2 tunable parameters : - source and drain bias
- plunger gate voltage
PG
[4] Hanson et al., Spins in few-electron QDs (2007), Rev. Mod. Phys., Vol. 79, No. 4
Anastasia Varlet 2/14 ETH - 05/04/12
I. Double Quantum Dot
2. Double Quantum Dot
[5] Picture from:
[5] Petta et al.,
Electrically-defined island → top gates on a 2DEG
Science 309 (2005)
2 tunable parameters : - source and drain bias
- plunger gate voltages
[4]
V
L
V
R
[1] T. Ihn, Semiconductor Nanostructures (2009), Oxford University Press.

Anastasia Varlet 3/14 ETH - 05/04/12
I. Double Quantum Dot
3. Two-electron regime
[3] Picture from:
[3] Petta et al.,
A Quantum Point Contact is used to determine Science 309 (2005)
the charge state in the dots.
[4]
[3]
V
L
V
R
[1] T. Ihn, Semiconductor Nanostructures (2009), Oxford University Press.

Anastasia Varlet 4/14 ETH - 05/04/12
I. Double Quantum Dot
3. Two-electron regime
[5] Picture from:
[5] Petta et al.,
A Quantum Point Contact is used to determine
Science 309 (2005)
the charge state in the dots.
[3]

Anastasia Varlet 5/14 ETH - 05/04/12
I. Double Quantum Dot
3. Two-electron regime
[3]
[5]
[4] Hanson et al., Spins in few-electron QDs (2007),
Rev. Mod. Phys., Vol. 79, No. 4
∆V
ε = η∆V

Anastasia Varlet 6/14 ETH - 05/04/12