PHYSIQUE MESOSCOPIQUE IPCMS DMONS Rodolfo Jalabert Dietmar Weinmann

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

Domaines de recherche : 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. )

Conductance à travers de systèmes fortement corrélés

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

Landauer: conductance from scattering Two terminal conductance: - 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

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

Numerical implementation

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

Even-odd asymmetry and Coulomb blockade LS odd: Resonance NS NS +1 electrons in the interacting region Coulomb blockade resonance (half filling) LS 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.

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

Interaction-induced non-local effects universal correction!

0. 7 anomaly D. A. Wharam et al, J. Phys. C, 1988 M. A. Topinka et al, Nature, 2001 Conductance quantization in a point contact

Nanoparticules métalliques

MIE THEORY On the color of gold colloids - 1908 λ >> 2 a in a metal: resonance pour surface plasmon

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

TIME RESOLVED EXPERIMENTS, POMP-PROBE Differential transmission (ps) (e. V) ps ps correlated scattering energyelectrons transfer e-ee-phonons & e-surface scattering, collective modes relaxation tomatrix the lattice to thermal distribution nonthermal cooling of theregime distribution Bigot et al. , Chem. Phys. , 2000

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

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

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

SPIN DIPOLE EXCITATION dipole absorption cross-section

Décohérence et dissipation

Spin echo (Hahn) H -H

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

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