
Correlated electron transport in 1d
M. Sassetti , A. Fechner, G. Cuniberti, and B. Kramer
225th International Wilhelm Heinrich und Else Heraeus Seminar on ``Electron Transport in Reduced Dimensions  Concepts and Reality''
1999.10; Bad Honnef, Bonn, Germany
 The dynamical interplay between currents and
electromagnetic fields belongs to one of the
fundamental and open problems. A key issue is to
describe the acphenomena of quantum systems
selfconsistently, in the presence of correlations and
nonlinearity [1]. We address this topic for frequency
dependent transport of interacting electrons in 1d. In
the linear regime we determine the longitudinal and
transverse acresponse. The space dependence of the
local electromagnetic fields is evaluated
selfconsistently. As a particular example, we
determine the complex absorptive conductance for a
longitudinal ac field. It is analyzed in terms of
resistive, capacitive and inductive contributions [2].
In the nonlinear case we investigate acproperties
created by the presence of a tunnel barrier. ``Single
charge tunneling'' is considered microscopically by
calculating the timedependent nonlinear current
response to a monochromatic external voltage. The DC
currentvoltage characteristics is calculated taking
into account electronelectron interaction of
finiterange [3]. For intermediate interaction
strengths, the nonlinear differential conductance
shows cusplike minima at integer ratios of the bias
voltages with the driving frequency $\Omega$. This
frequencylocking effect, is a signature of the systems
coherent, strongly correlated electron states and
it is characteristic of the finite, nonzero range of
the interaction but does not depend on the exact shape
of the driving electric field. However, the
frequencyscaling of the photoinduced current shows a
crossover between ^{1} and ^{2}, and depends on the spatial
shape of the driving field. Due to intrinsic
nonlinearity, the system shows also harmonic
generation. We explicitly evaluate the current and
discuss the nonFermi liquid dependence on the
interaction strength [4]. Quantitative results for the
electromagnetic radiation are provided especially in
the near field region. Specifically, we demonstrate
that the electromagnetic power is emitted perpendicular
to the quantum wire close to the tunnel barrier, while
it is radiated parallel to the wire away from the
barrier.
[1] O. Keller, Phys. Rep. 268,
85 (1996). [2] G. Cuniberti, M. Sassetti, B.
Kramer, Phys. Rev. B57, 1515 (1998). [3] G.
Cuniberti, A. Fechner, M. Sassetti, B. Kramer, preprint
[4] A. Fechner, M. Sassetti, B. Kramer, Europhys.
Lett., 45, 693 (1999).



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Prof. Dr. Gianaurelio Cuniberti
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postal address:
Institute for Materials Science
TU Dresden
01062 Dresden, Germany
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