29,845 research outputs found
Multimode theory of measurement-induced non-Gaussian operation on wideband squeezed light
We present a multimode theory of non-Gaussian operation induced by an
imperfect on/off-type photon detector on a splitted beam from a wideband
squeezed light. The events are defined for finite time duration in the time
domain. The non-Gaussian output state is measured by the homodyne detector with
finite bandwidh . Under this time- and band-limitation to the quantm states,
we develop a formalism to evaluate the frequency mode matching between the
on/off trigger channel and the conditional signal beam in the homodyne channel.
Our formalism is applied to the CW and pulsed schemes. We explicitly calculate
the Wigner function of the conditional non-Gaussian output state in a realistic
situation. Good mode matching is achieved for BT\alt1, where the discreteness
of modes becomes prominant, and only a few modes become dominant both in the
on/off and the homodyne channels. If the trigger beam is projected nearly onto
the single photon state in the most dominant mode in this regime, the most
striking non-classical effect will be observed in the homodyne statistics. The
increase of and the dark counts degrades the non-classical effect.Comment: 20 pages, 14 figures, submitted to Phys. Rev.
Axial anomaly with the overlap-Dirac operator in arbitrary dimensions
We evaluate for arbitrary even dimensions the classical continuum limit of
the lattice axial anomaly defined by the overlap-Dirac operator. Our
calculational scheme is simple and systematic. In particular, a powerful
topological argument is utilized to determine the value of a lattice integral
involved in the calculation. When the Dirac operator is free of species
doubling, the classical continuum limit of the axial anomaly in various
dimensions is combined into a form of the Chern character, as expected.Comment: 9 pages, uses JHEP.cls and amsfonts.sty, the final version to appear
in JHE
Evolution of deformations in medium-mass nuclei
Evolution of quadrupole deformations in and shell nuclei with mass
A= 1856 is studied by using deformed Skyrme Hartree-Fock (HF) model with
pairing correlations. We point out that the quadrupole deformations of the
nuclei with the isospin T=0 and T=1 show strong mass number dependence as a
clear manifestation of dynamical evolution of deformation in nuclear many-body
systems. The competition between the deformation driving particle-vibration
coupling and the closed shell structure is shown in a systematic study of the
ratios between the proton and neutron deformations in nuclei with
T=T=1. Calculated quadrupole and hexadecapole deformations are compared
with shell model results and available experimental data. A relation between
the skin thickness and the intrinsic Q moments is also discussed.Comment: 26 pages, 8figure
Distinct Fe-induced magnetic states in the underdoped and overdoped regimes of La2-xSrxCu1-yFeyO4 revealed by muon spin relaxation
Zero-field and longitudinal-field muon-spin-relaxation measurements have been
performed in partially Fe-substituted La2-xSrxCu1-yFeyO4 in a wide range of
hole concentration, to investigate the magnetic state induced by the Fe
substitution recently suggested from the neutron-scattering measurements [Phys.
Rev. Lett. 107, 127002 (2011)]. It has been found that the magnetic transition
temperature is notably enhanced through the 1% Fe substitution in a wide range
of hole concentration where superconductivity appears in Fe-free La2-xSrxCuO4.
In the underdoped regime, the Fe-induced magnetic order can be understood in
terms of the concept of stripe pinning by Fe as in the case of the Zn-induced
one in La2-xSrxCu1-yZnyO4. In the overdoped regime, on the other hand, the
Fe-induced magnetic order is short-ranged, which is distinct from the stripes.
It is plausible that a spin-glass state of Fe spins derived from the
Ruderman-Kittel-Kasuya-Yosida interaction is realized in the overdoped regime,
suggesting a change of the ground state from the strongly correlated state to
the Fermi-liquid state with hole doping in La-214 high-Tc cuprates.Comment: 10 pages, 6 figures, accepted for publication in Phys. Rev.
An Almost Perfect Quantum Lattice Action for Low-energy SU(2) Gluodynamics
We study various representations of infrared effective theory of SU(2)
Gluodynamics as a (quantum) perfect lattice action. In particular we derive a
monopole action and a string model of hadrons from SU(2) Gluodynamics. These
are lattice actions which give almost cut-off independent physical quantities
even on coarse lattices. The monopole action is determined by numerical
simulations in the infrared region of SU(2) Gluodynamics. The string model of
hadrons is derived from the monopole action by using BKT transformation. We
illustrate the method and evaluate physical quantities such as the string
tension and the mass of the lowest state of the glueball analytically using the
string model of hadrons. It turns out that the classical results in the string
model is near to the one in quantum SU(2) Gluodynamics.Comment: 39 pages, 10 figure
Muon spin relaxation and rotation study on the solid solution of the two spin-gap systems (CH3)2CHNH3-CuCl3 and (CH3)2CHNH3-CuBr3
Muon-spin-rotation and relaxation studies have been performed on
(CH)CHNHCu(ClBr) with =0.85 and 0.95, which are
solid solutions of the two isomorphic spin-gap systems
(CH)CHNHCuCl and (CH)CHNHCuBr with different
spin gaps. The sample with =0.85 showed a clear muon spin rotation under
zero-field below =11.65K, indicating the existence of a long-range
antiferromagnetic order. A critical exponent of the hyperfine field was
obtained to be =0.33, which agrees with 3D-Ising model. In the other
sample with =0.95, an anomalous enhancement of the muon spin relaxation was
observed at very low temperatures indicating a critical slowing down due to a
magnetic instability of the ground state
Solving the local cohomology problem in U(1) chiral gauge theories within a finite lattice
In the gauge-invariant construction of abelian chiral gauge theories on the
lattice based on the Ginsparg-Wilson relation, the gauge anomaly is topological
and its cohomologically trivial part plays the role of the local counter term.
We give a prescription to solve the local cohomology problem within a finite
lattice by reformulating the Poincar\'e lemma so that it holds true on the
finite lattice up to exponentially small corrections. We then argue that the
path-integral measure of Weyl fermions can be constructed directly from the
quantities defined on the finite lattice.Comment: revised version, 35pages, using JHEP3.cl
Baryonic Flux in Quenched and Two-Flavor Dynamical QCD after Abelian projection
We study the distribution of color electric flux of the three-quark system in
quenched and full QCD (with N_f = 2 flavors of dynamical quarks) at zero and
finite temperature. To reduce ultra-violet fluctuations, the calculations are
done in the abelian projected theory fixed to the maximally abelian gauge. In
the confined phase we find clear evidence for a Y--shape flux tube surrounded
and formed by the solenoidal monopole current, in accordance with the dual
superconductor picture of confinement. In the deconfined, high temperature
phase monopoles cease to condense, and the distribution of the color electric
field becomes Coulomb--like.Comment: 21 pages, 15 figures, Latex, published version (4 figures added
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