135 research outputs found
Państwa i narody pogranicza. Charakterystyka geopolityczna ziem i społeczeństw północno-wschodniej Europy w pracach Voltaire’a Histoire de Charles XII, roi de Suède i Montesquieu De l'esprit des lois
Zadanie pt. Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki nr 885/P-DUN/2014 zostało dofinansowane ze środków MNiSW w ramach działalności upowszechniającej naukę
Universal Scaling in Non-equilibrium Transport Through a Single-Channel Kondo Dot
Scaling laws and universality play an important role in our understanding of
critical phenomena and the Kondo effect. Here we present measurements of
non-equilibrium transport through a single-channel Kondo quantum dot at low
temperature and bias. We find that the low-energy Kondo conductance is
consistent with universality between temperature and bias and characterized by
a quadratic scaling exponent, as expected for the spin-1/2 Kondo effect. The
non-equilibrium Kondo transport measurements are well-described by a universal
scaling function with two scaling parameters.Comment: v2: improved introduction and theory-experiment comparsio
Engineering the Kondo and Fano effects in double quantum dots
We demonstrate delicate control over the Kondo effect and its interplay with
quantum interference in an Aharonov-Bohm interferometer containing one Kondo
dot and one noninteracting dot. It is shown that the Kondo resonance undergoes
a dramatic evolution as the interdot tunnel coupling progressively increases. A
novel triple Kondo splitting occurs from the interference between constant and
Lorentzian conduction bands that cooperate in forming the Kondo singlet. The
device also manifests a highly controllable Fano-Kondo effect in coherent
electronic transport, and can be tuned to a regime where the coupled dots
behave as decoupled dots.Comment: 5 pages, 4 figure
Non-equilibrium transport theory of the singlet-triplet transition: perturbative approach
We use a simple iterative perturbation theory to study the singlet-triplet
(ST) transition in lateral and vertical quantum dots, modeled by the
non-equilibrium two-level Anderson model. To a great surprise, the region of
stable perturbation theory extends to relatively strong interactions, and this
simple approach is able to reproduce all experimentally-observed features of
the ST transition, including the formation of a dip in the differential
conductance of a lateral dot indicative of the two-stage Kondo effect, or the
maximum in the linear conductance around the transition point. Choosing the
right starting point to the perturbation theory is, however, crucial to obtain
reliable and meaningful results
Persistent currents through a quantum impurity: Protection through integrability
We consider an integrable model of a one-dimensional mesoscopic ring with the
conduction electrons coupled by a spin exchange to a magnetic impurity. A
symmetry analysis based on a Bethe Ansatz solution of the model reveals that
the current is insensitive to the presence of the impurity. We argue that this
is true for any integrable impurity-electron interaction, independent of choice
of physical parameters or couplings. We propose a simple physical picture of
how the persistent current gets protected by integrability.Comment: 5 pages, minor update
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