1. The noise spectrum of a quantum dot
Eitan Rothstein Netanel Gabdank
Ora Entin-Wohlman* Amnon Aharony*
Physics Department, Ben Gurion University of the Negev
* Also at Tel Aviv University

2. Mesoscopic Physics 2/10 Meso = Intermidiate, in the middle.
Mesoscopic physics = A mesoscopic system is really like a large molecule, but it is always, at least weakly, coupled to a much larger, essentially infinite, system – via phonos, many body excitation, and so on. (Y. Imry, Introduction to mesoscopic physics)
A naïve definition: Something very small coupled to something very large.
2/10

3. Mesoscopic Physics
3/10

4. Quantum dot 4/10 There are different types of quantum dots.
A large atom connecting to two ledas
A metallic grain on a surface
Voltage gates on 2DEG
4/10

5. The model 5/10 The model DC conductance Noise spectrum
Quantum-Dot (QD) N∆
Left (L)
electronic
reservoir
Right (R)
electronic
reservoir … ∆
-N∆
DC conductance
Noise spectrum
No interaction
Hartree Fock
5/10

6. The model 6/10 The Hamiltonian Hartree Fock approximation
electronic
states on QD
charging energy
momentum states in
R/L reservoirs
coupling
R/L reservoir-QD
Hartree Fock approximation
Hartree
Fock
Self-consistent calculation
6/10

7. Level Occupancy and Effective Hamiltonian
The effective Hamiltonian
* energy scaled with
Level Occupancy
Effective single-e energies
(Hartree)
(Hartree)
(Hartree Fock)
(Hartree Fock)
Hartree terms
Fock terms
Hartree terms
Fock terms
7/10

8. The Scattering Formalism
Treating the problem in the Landauer Büttiker formalism
Tight-Binding model
Current and correlations
S(E)
scattering
region
states
(Landauer)
(Büttiker)
8/10

9. The noise spectrum 9/10 Noise spectrum * energy scaled with
Calculations performed for and , so the noise given by
symmetric
symmetric
Hartree
No interaction
Hartree
Hartree Fock
symmetric
asymmetric
Hartree Fock
No interaction
Hartree
Hartree Fock
9/10

10. Thanks Summary 10/10 “The noise is the signal” - R. Landauer
The noise spectrum exhibits steps and dips
The steps quantum dot resonances
The dips energy difference between the resonances
contain information on the coupling asymmetry
The interaction effect
Shifts levels to preserves neutrality
Shifts noise steps and dips
Fock effect
Small quantitative effect – modifies the width of the levels
Thanks
10/10