229 research outputs found
All Optical Measurement Proposed for the Photovoltaic Hall Effect
We propose an all optical way to measure the recently proposed "photovoltaic
Hall effect", i.e., a DC Hall effect induced by a circularly polarized light in
the absence of static magnetic fields. For this, we have calculated the Faraday
rotation angle induced by the photovoltaic Hall effect with the Kubo formula
extended for photovoltaic optical response in the presence of strong AC
electric fields treated with the Floquet formalism. We also point out the
possibility of observing the effect in three-dimensional graphite, and more
generally in multi-band systems such as materials described by the dp-model.Comment: 5 page
Confinement Phase in Carbon-Nanotubes and the Extended Massive Schwinger Model
Carbon nanotube with electric fluxes confined in one dimension is studied. We
show that a Coulomb interaction \propto |x| leads to a confinement phase with
many properties similar to QCD in 4D. Low-energy physics is described by the
massive Schwinger model with multi-species fermions labeled by the band and
valley indices. We propose two means to detect this state. One is through an
optical measurement of the exciton spectrum, which has been calculated via the
't Hooft-Berknoff equation with the light-front field theory. We show that the
Gell-Mann-Oakes-Renner relation is satisfied by a dark exciton. The second is
the nonlinear transport which is related to Coleman's "half-asymptotic" state.Comment: 5 pages, 3 figure
Nonlinear Transport in One-Dimensional Mott Insulator in Strong Electric Fields
Time-dependent Schroedinger's equation is integrated for a one-dimensional
strongly-correlated electron system driven by large electric fields. For larger
electric fields, many-body Landau-Zener tunneling takes place at anti-crossings
of the many-body energy levels. The nonlinear - characteristics as well
as the time dependence of the energy expectation value are obtained. The energy
of the Mott insulator in electric fields shows a saturation, which suggests a
dynamical localization in energy space of many-body wave functions.Comment: 3 pages, 3 figures, Proceedings of SCES'04 (Karlsruhe
Probing and controlling spin chirality in Mott insulators by circularly polarized laser
Scalar spin chirality, a three-body spin correlation that breaks
time-reversal symmetry, is revealed to couple directly to circularly polarized
laser. This is shown by the Floquet formalism for the periodically driven
repulsive Hubbard model with a strong-coupling expansion. A systematic
derivation of the effective low-energy Hamiltonian for a spin degree of freedom
reveals that the coupling constant for scalar spin chirality can become
significant for a situation in which the driving frequency and the on-site
interaction are comparable. This implies that the scalar chirality can be
induced by circularly polarized lights, or that it can be used conversely for
probing the chirality in Mott insulators as a circular dichroism.Comment: 10 pages, 8 figure
Nonequilibrium Steady State of Photoexcited Correlated Electrons in the Presence of Dissipation
We present a framework to determine nonequilibrium steady states in strongly
correlated electron systems in the presence of dissipation. This is
demonstrated for a correlated electron (Falicov-Kimball) model attached to a
heat bath and irradiated by an intense pump light, for which an exact solution
is obtained with the Floquet method combined with the nonequilibrium dynamical
mean-field theory. On top of a Drude-like peak indicative of photometallization
as observed in recent pump-probe experiments, new nonequilibrium phenomena are
predicted to emerge, where the optical conductivity exhibits dip and kink
structures around the frequency of the pump light, a midgap absorption arising
from photoinduced Floquet subbands, and a negative attenuation (gain) due to a
population inversion.Comment: 5 pages, 3 figures, published versio
The Determination of the Quark-Gluon Mixed Condensate (anti-Q sigma G Q) from Lattice QCD
We study the quark-gluon mixed condensate g, using the
SU(3)c lattice QCD with the Kogut-Susskind fermion at the quenched level. We
generate 100 gauge configurations on the 16^4 lattice with \beta = 6.0, and
perform the measurement of the mixed condensate at 16 points in each gauge
configuration for each current quark mass of m_q=21, 36, 52 MeV. Using the 1600
data for each m_q, we find the ratio between the mixed condensate and the quark
condensate, m_0^2 = g / \simeq 2.5 GeV^2 at the
lattice scale of 1/a \simeq 2 GeV in the chiral limit. The large value of the
mixed condensate suggests its importance in the operator product expansions in
QCD. We study also chiral restoration at finite temperature in terms of the
mixed condensate, which is another chiral order parameter. We present the
lattice QCD results of the mixed condensate at finite temperature.Comment: 5 pages, Talk given at Tokyo-Adelaide Joint Workshop on Quarks,
Astrophysics and Space physics, Tokyo, Japan, Jan.6 - Jan.10, 200
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