IPCMS - DMONS

Post-docs: Jérôme Roccia (DMONS-DON)

Guillaume Weick

PHYSIQUE MESOSCOPIQUEPHYSIQUE MESOSCOPIQUE

Rodolfo JalabertDietmar Weinmann

Etudiants: Guido Intronati (Strasbourg – Buenos Aires)

Wojciech Szewc

Conductance à travers de systèmes fortement corrélésRelaxation 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 :

Conductance à travers de systèmes fortement corrélés

individual object

universality

size

interactionsnon-local

effects

nano

Quantum transport

- 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

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!

Numerical implementation

Conductance through a correlated region

g decreases with U

g decreases with LS

Mott insulator

g ≈ 1 for LS odd

Perfect conductance only with adiabatic contacts

W = 0

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 waveguideLlang, et al, Nature ’01.

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-

non local effect !

ohmic composition

Interaction-induced non-local effects

universal correction!

D.A. Wharam et al, J. Phys. C, 1988

Conductance quantization in a point contact

M.A. Topinka et al, Nature, 2001 0.7 anomaly

Nanoparticules métalliques

in a metal:

MIE THEORYMIE THEORY On the color of gold colloids -

1908

λ >> 2a

resonance pour surface plasmon

Bréchignac et al, PRL 1993

(visible)

Photo-absorption cross section of 12C nucleus

Plasmon resonance in free clusters

Differential transmission

Bigot et al., Chem. Phys., 2000

(ps)

(eV)

pscorrelated electrons

collective modesnonthermal regime

e-e & e-surface scattering,

thermal distribution

e-phonons scatteringrelaxation to the lattice

cooling of the distribution

energy transfer to the matrix

TIME RESOLVED EXPERIMENTS, POMP-PROBETIME RESOLVED EXPERIMENTS, POMP-PROBE

pspsps

One-particle potential: uniform

jellium background with a

Coulomb tail

COLLECTIVE AND RELATIVE COORDINATESCOLLECTIVE AND RELATIVE COORDINATES

center of mass: harmonic oscillator

plasmonplasmon

relative coordinates: mean field

coupling: dipole field

Kawabata & Kubo, 1966

Time-Dependent Local Density Approximation

Nonmonotonic behavior !!

Na

SIZE-OSCILLATIONS OF THE LINEWIDTHSIZE-OSCILLATIONS OF THE LINEWIDTH

Drude, Drude, τ‾τ‾11

confinement, confinement, aa << ττ vvFF

Semiclassical approach

PLASMON AS A COLLECTIVE EXCITATION PLASMON AS A COLLECTIVE EXCITATION

RPA eigenenergies :

PlasmonPlasmon = superposition of low-energy e-hlow-energy e-h coupled to

high-energy high-energy e-he-h

restricted subspace

additional subspace

dipole absorption cross-section

SPIN DIPOLE EXCITATIONSPIN DIPOLE EXCITATION

Décohérence et dissipation

HH -H-H

Spin echo (Hahn)

Loschmidt echoLoschmidt echo (fidelity) in the presence of a weak coupling to the environment

||00

||HH00tt

MM(t) = (t) = ||00| exp[+| exp[+i(i(HH00++))tt] exp[-] exp[-iiHH00tt] |] |00||22

HH00HH00

- H- H

||HH00 ,, - -H H 2t2t

||HH00tt||HHtt

||00

HH

H=HH=H00++environmentenvironment

How does How does MM(t)(t) depend on depend on HH00 ,, , and, and t t ? ?

Time-reversal focusing

C. Draeger, M. Fink, PRL 1997