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The noise spectrum of a quantum dot

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. Mesoscopic Physics. Meso = Intermidiate, in the middle.

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The noise spectrum of a quantum dot

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  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 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 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 The model 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 The Hamiltonian 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 terms Fock terms Hartree terms Fock terms (Hartree Fock) (Hartree Fock) 7/10

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

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

  10. Summary “The noise is the signal” - R. Landauer t • 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

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