259 research outputs found
Luttinger liquids with curvature: Density correlations and Coulomb drag effect
We consider the effect of the curvature in fermionic dispersion on the
observable properties of Luttinger liquid (LL). We use the bosonization
technique where the curvature is irrelevant perturbation, describing the decay
of LL bosons (plasmon modes). When possible, we establish the correspondence
between the bosonization and the fermionic approach. We analyze modifications
in density correlation functions due to curvature at finite temperatures, T.
The most important application of our approach is the analysis of the Coulomb
drag by small momentum transfer between two LL, which is only possible due to
curvature. Analyzing the a.c. transconductivity in the one-dimensional drag
setup, we confirm the results by Pustilnik et al. for T-dependence of drag
resistivity, R_{12} ~ T^2 at high and R_{12} ~ T^5 at low temperatures. The
bosonization allows for treating both intra- and inter-wire electron-electron
interactions in all orders, and we calculate exact prefactors in low-T drag
regime. The crossover temperature between the two regimes is T_1 ~ E_F \Delta,
with \Delta relative difference in plasmon velocities. We show that \Delta \neq
0 even for identical wires, due to lifting of degeneracy by interwire
interaction, U_{12}, leading to crossover from R_{12} ~ U_{12}^2 T^2 to R_{12}
\~ T^5/U_{12} at T ~ U_{12}.Comment: 16 pages, 10 figures, REVTE
The mean energy, strength and width of triple giant dipole resonances
We investigate the mean energy, strength and width of the triple giant dipole
resonance using sum rules.Comment: 12 page
Correlated sequential tunneling through a double barrier for interacting one-dimensional electrons
The problem of resonant tunneling through a quantum dot weakly coupled to
spinless Tomonaga-Luttinger liquids has been studied. We compute the linear
conductance due to sequential tunneling processes upon employing a master
equation approach. Besides the previously used lowest-order golden rule rates
describing uncorrelated sequential tunneling (UST) processes, we systematically
include higher-order correlated sequential tunneling (CST) diagrams within the
standard Weisskopf-Wigner approximation. We provide estimates for the parameter
regions where CST effects can be important. Focusing mainly on the temperature
dependence of the peak conductance, we discuss the relation of these findings
to previous theoretical and experimental results.Comment: replaced with the published versio
Signatures of Strong Correlations in One-Dimensional Ultra-Cold Atomic Fermi Gases
Recent success in manipulating ultra-cold atomic systems allows to probe
different strongly correlated regimes in one-dimension. Regimes such as the
(spin-coherent) Luttinger liquid and the spin-incoherent Luttinger liquid can
be realized by tuning the inter-atomic interaction strength and trap
parameters. We identify the noise correlations of density fluctuations as a
robust observable (uniquely suitable in the context of trapped atomic gases) to
discriminate between these two regimes. Finally, we address the prospects to
realize and probe these phenomena experimentally using optical lattices.Comment: 4 pages, 2 figure
Ground-state phase diagram of the one-dimensional Hubbard-model with an alternating potential
We investigate the ground-state phase diagram of the one-dimensional
half-filled Hubbard model with an alternating potential--a model for the
charge-transfer organic materials and the ferroelectric perovskites. We
numerically determine the global phase diagram of this model using the
level-crossing and the phenomenological renormalization-group methods based on
the exact diagonalization calculations. Our results support the mechanism of
the double phase transitions between Mott and a band insulators pointed out by
Fabrizio, Gogolin, and Nersesyan [Phys. Rev. Lett. 83, 2014 (1999)]: We confirm
the existence of the spontaneously dimerized phase as an intermediate state.
Further we provide numerical evidences to check the criticalities on the phase
boundaries. Especially, we perform the finite-size-scaling analysis of the
excitation gap to show the two-dimensional Ising transition in the charge part.
On the other hand, we confirm that the dimerized phase survives in the
strong-coupling limit, which is one of the resultants of competition between
the ionicity and correlation effects.Comment: 8 pages, 8 figure
Transmission of correlated electrons through sharp domain walls in magnetic nanowires: a renormalization group approach
The transmission of correlated electrons through a domain wall in a
ferromagnetic one dimensional system is studied theoretically in the limit of a
domain wall width smaller or comparable to the electron Fermi wavelength. The
domain wall gives rise to both potential and spin dependent scattering of the
charge carriers. Using a poor man's renormalization group approach for the
electron-electron interactions, we obtain the low temperature behavior of the
reflection and transmission coefficients. The results show that the
low-temperature conductance is governed by the electron correlations, which may
suppress charge transport without suppressing spin current. The results may
account for a huge magnetoresistance associated with a domain wall in ballistic
nanocontacs.Comment: 13 pages, 6 figure
Spin-excitations of the quantum Hall ferromagnet of composite fermions
The spin-excitations of a fractional quantum Hall system are evaluated within
a bosonization approach. In a first step, we generalize Murthy and Shankar's
Hamiltonian theory of the fractional quantum Hall effect to the case of
composite fermions with an extra discrete degree of freedom. Here, we mainly
investigate the spin degrees of freedom, but the proposed formalism may be
useful also in the study of bilayer quantum-Hall systems, where the layer index
may formally be treated as an isospin. In a second step, we apply a
bosonization scheme, recently developed for the study of the two-dimensional
electron gas, to the interacting composite-fermion Hamiltonian. The dispersion
of the bosons, which represent quasiparticle-quasihole excitations, is
analytically evaluated for fractional quantum Hall systems at \nu = 1/3 and \nu
= 1/5. The finite width of the two-dimensional electron gas is also taken into
account explicitly. In addition, we consider the interacting bosonic model and
calculate the lowest-energy state for two bosons. Besides a continuum
describing scattering states, we find a bound-state of two bosons. This state
is interpreted as a pair excitation, which consists of a skyrmion of composite
fermions and an antiskyrmion of composite fermions. The dispersion relation of
the two-boson state is evaluated for \nu = 1/3 and \nu = 1/5. Finally, we show
that our theory provides the microscopic basis for a phenomenological
non-linear sigma-model for studying the skyrmion of composite fermions.Comment: Revised version, 14 pages, 4 figures, accepted to Phys. Rev.
Newton's law for Bloch electrons, Klein factors and deviations from canonical commutation relations
The acceleration theorem for Bloch electrons in a homogenous external field
is usually presented using quasiclassical arguments. In quantum mechanical
versions the Heisenberg equations of motion for an operator
are presented mostly without properly defining this operator. This leads to the
surprising fact that the generally accepted version of the theorem is incorrect
for the most natural definition of . This operator is shown not
to obey canonical commutation relations with the position operator. A similar
result is shown for the phase operators defined via the Klein factors which
take care of the change of particle number in the bosonization of the field
operator in the description of interacting fermions in one dimension. The phase
operators are also shown not to obey canonical commutation relations with the
corresponding particle number operators. Implications of this fact are
discussed for Tomonaga-Luttinger type models.Comment: 9 pages,1 figur
Revisiting Mt. Fuji's groundwater origins with helium, vanadium and eDNA tracers
Known locally as the water mountain , for millennia Japan's iconic Mt. Fuji has provided safe drinking water to millions of people via a vast network of groundwater and freshwater springs. Groundwater, which is recharged at high elevations, flows down Fuji's flanks within three basaltic aquifers, ultimately forming countless pristine freshwater springs along Fuji's foothills. Here, we challenge the current conceptual model of Fuji being a simple system of laminar groundwater flow with little to no vertical exchange between its three aquifers. This model contrasts strongly with Fuji's extreme tectonic instability due to its unique location on top of the only known continental trench-trench-trench triple junction, its complex geology, and its unusual microbial spring water communities. Based on a unique combination of microbial environmental DNA (eDNA), vanadium, and helium tracers, we provide evidence for prevailing deep circulation and previously unknown deep groundwater contribution to Fuji's freshwater springs. The most substantial deep groundwater upwelling has been found along Japan's tectonically most active Fujikawa-kako Fault Zone. Our findings broaden the hydrogeological understanding of Fuji and demonstrate the vast potential of combining eDNA, on-site noble gas, and trace element analyses for groundwater science
One-dimensional Kondo lattice at partial band filling
An effective Hamiltonian for the localized spins in the one-dimensional Kondo
lattice model is derived via a unitary transformation involving a bosonization
of delocalized conduction electrons. The effective Hamiltonian is shown to
reproduce all the features of the model as identified in various numerical
simulations, and provides much new information on the ferro- to paramagnetic
phase transition and the paramagnetic phase.Comment: 11 pages Revtex, 1 Postscript figure. To appear in Phys. Rev. Let
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