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IPCMS - DMONS Post-docs: Jérôme Roccia (DMONS-DON) Guillaume Weick PHYSIQUE MESOSCOPIQUE PHYSIQUE MESOSCOPIQUE Rodolfo Jalabert Dietmar Weinmann Etudiants:

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Presentation on theme: "IPCMS - DMONS Post-docs: Jérôme Roccia (DMONS-DON) Guillaume Weick PHYSIQUE MESOSCOPIQUE PHYSIQUE MESOSCOPIQUE Rodolfo Jalabert Dietmar Weinmann Etudiants:"— Presentation transcript:

1 IPCMS - DMONS Post-docs: Jérôme Roccia (DMONS-DON) Guillaume Weick PHYSIQUE MESOSCOPIQUE PHYSIQUE MESOSCOPIQUE Rodolfo Jalabert Dietmar Weinmann Etudiants: Guido Intronati (Strasbourg – Buenos Aires) Wojciech Szewc

2 Conductance à travers de systèmes fortement corrélés Relaxation du spin Transport dépendant de spin Nanoparticules métalliques Electronique moléculaire (G.W.) Courants permanents et interactions (D.W.) Décohérence et dissipation (R.J.) Domaines de recherche :

3 Conductance à travers de systèmes fortement corrélés

4 individual object universality size interactions non-local effects nano Quantum transport

5 - Separation of sample, leads and reservoirs - Mean field, quasi-particle scattering states at the Fermi energy - Equilibration in the reservoirs leads to dissipation - Contact resistance Two terminal conductance: Landauer: conductance from scattering

6 Conductance through an interacting region - How do we calculate the transmission coefficient T ? - Is the scattering approach still valid ? without inelastic process (zero temperature) persistent current for interacting region + leads embedding method Ground-state property!

7 Numerical implementation

8 Conductance through a correlated region g decreases with U g decreases with L S Mott insulator g 1 for L S odd Perfect conductance only with adiabatic contacts W = 0

9 Even-odd asymmetry and Coulomb blockade L S odd: Resonance N S N S +1 electrons in the interacting region Coulomb blockade resonance (half filling) L S even: Transport involves charging energy U Interacting region is a barrier Observation of a parity oscillation in the conductance of atomic wires: R.H.M. Smit, et al, PRL 03 Fabry-Perot interference in a nanotube electron waveguide Llang, et al, Nature 01.

10 Can we describe an interacting region by an effective one-particle scatterer? R = R + + R - R R + + R - Quantum mechanics, non-locality S = S + * S - Electron-electron interactions S+S+ S-S- S S + * S - non local effect ! ohmic composition

11 Interaction-induced non-local effects universal correction!

12 D.A. Wharam et al, J. Phys. C, 1988 Conductance quantization in a point contact M.A. Topinka et al, Nature, anomaly

13 Nanoparticules métalliques

14 in a metal: MIE THEORY MIE THEORY On the color of gold colloids λ >> 2a resonance pour surface plasmon

15 Bréchignac et al, PRL 1993 (visible) Photo-absorption cross section of 12 C nucleus Plasmon resonance in free clusters

16 Differential transmission Bigot et al., Chem. Phys., 2000 (ps) (eV) ps correlated electrons collective modes nonthermal regime e-e & e-surface scattering, thermal distribution e-phonons scattering relaxation to the lattice cooling of the distribution energy transfer to the matrix TIME RESOLVED EXPERIMENTS, POMP-PROBE TIME RESOLVED EXPERIMENTS, POMP-PROBE ps

17 One-particle potential: uniform jellium background with a Coulomb tail COLLECTIVE AND RELATIVE COORDINATES COLLECTIVE AND RELATIVE COORDINATES center of mass: harmonic oscillator plasmon relative coordinates: mean field coupling: dipole field

18 Kawabata & Kubo, 1966 Time-Dependent Local Density Approximation Nonmonotonic behavior !! Na SIZE-OSCILLATIONS OF THE LINEWIDTH SIZE-OSCILLATIONS OF THE LINEWIDTH Drude, τ 1 confinement, a < τ v F Semiclassical approach

19 PLASMON AS A COLLECTIVE EXCITATION PLASMON AS A COLLECTIVE EXCITATION RPA eigenenergies : Plasmon Plasmon = superposition of low-energy e-h low-energy e-h coupled to high-energy e-h restricted subspace additional subspace

20 dipole absorption cross-section SPIN DIPOLE EXCITATION

21 Décohérence et dissipation

22 H -H Spin echo (Hahn)

23 Loschmidt echo Loschmidt echo (fidelity) in the presence of a weak coupling to the environment | 0 | 0 | H 0 t M(t) = | 0 | exp[+ i(H 0 + ) t ] exp[- iH 0 t ] | 0 | 2 H0H0H0H0 H0H0H0H0 - H | H 0, -H 2t | H 0 t | H t | 0 | 0 H H=H 0 + H=H 0 + environment How does M(t) depend on H 0,, and t ?

24 Time-reversal focusing C. Draeger, M. Fink, PRL 1997


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