1,495 research outputs found
Bogoliubov Theory and Lee-Huang-Yang Corrections in Spin-1 and Spin-2 Bose-Einstein Condensates in the Presence of the Quadratic Zeeman Effect
We develop Bogoliubov theory of spin-1 and spin-2 Bose-Einstein condensates
(BECs) in the presence of a quadratic Zeeman effect, and derive the
Lee-Huang-Yang (LHY) corrections to the ground-state energy, sound velocity,
and quantum depletion. We investigate all the phases of spin-1 and spin-2 BECs
that can be realized experimentally. We also examine the stability of each
phase against quantum fluctuations and the quadratic Zeeman effect.
Furthermore, we discuss a relationship between the number of symmetry
generators that are spontaneously broken and that of Nambu-Goldstone (NG)
modes. It is found that in the spin-2 nematic phase there are special
Bogoliubov modes that have gapless linear dispersion relations but do not
belong to the NG modes.Comment: v3: 62 pages, 18 figure
Forecasting the Cosmological Constraints with Anisotropic Baryon Acoustic Oscillations from Multipole Expansion
Baryon acoustic oscillations (BAOs) imprinted in the galaxy power spectrum
can be used as a standard ruler to determine angular diameter distance and
Hubble parameter at high redshift galaxies. Combining redshift distortion
effect which apparently distorts the galaxy clustering pattern, we can also
constrain the growth rate of large-scale structure formation. Usually, future
forecast for constraining these parameters from galaxy redshift surveys has
been made with a full 2D power spectrum characterized as function of wavenumber
and directional cosine between line-of-sight direction and wave
vector, i.e., . Here, we apply the multipole expansion to the full 2D
power spectrum, and discuss how much cosmological information can be extracted
from the lower-multipole spectra, taking a proper account of the non-linear
effects on gravitational clustering and redshift distortion. The Fisher matrix
analysis reveals that compared to the analysis with full 2D spectrum, a partial
information from the monopole and quadrupole spectra generally degrades the
constraints by a factor of for each parameter. The additional
information from the hexadecapole spectrum helps to improve the constraints,
which lead to an almost comparable result expected from the full 2D spectrum.Comment: 12 pages, 6 figure
Scanning tunneling spectroscopy of superconducting LiFeAs single crystals: Evidence for two nodeless energy gaps and coupling to a bosonic mode
The superconducting compound, LiFeAs, is studied by scanning tunneling
microscopy and spectroscopy. A gap map of the unreconstructed surface indicates
a high degree of homogeneity in this system. Spectra at 2 K show two nodeless
superconducting gaps with meV and
meV. The gaps close as the temperature is increased to the bulk
indicating that the surface accurately represents the bulk. A dip-hump
structure is observed below with an energy scale consistent with a
magnetic resonance recently reported by inelastic neutron scattering
Deduction of Pure Spin Current from Spin Linear and Circular Photogalvanic Effect in Semiconductor Quantum Wells
We study the spin photogalvanic effect in two-dimensional electron system
with structure inversion asymmetry by means of the solution of semiconductor
optical Bloch equations. It is shown that a linearly polarized light may inject
a pure spin current in spin-splitting conduction bands due to Rashba spin-orbit
coupling, while a circularly polarized light may inject spin-dependent
photocurrent. We establish an explicit relation between the photocurrent by
oblique incidence of a circularly polarized light and the pure spin current by
normal incidence of a linearly polarized light such that we can deduce the
amplitude of spin current from the measured spin photocurrent experimentally.
This method may provide a source of spin current to study spin transport in
semiconductors quantitatively
Short Terahertz Pulses from Semiconductor Surfaces: The Importance of Bulk Difference‐Frequency Mixing
The crystallographic orientation dependence of the far‐infrared (FIR) light generated at the (001) surface of a zincblende semiconductor is shown to derive principally from bulk difference‐frequency mixing. A strong modulation is observed for 1‐GW/cm2 pulses on InP, which demonstrates that the radiated FIR wave produced by bulk optical rectification is comparable to that generated by the transport of photoinjected carriers. Using the bulk rectification light as a clock, we show that more than 95% of the light produced from an InP (111) crystal by 100‐fs, 100‐μJ pulses is generated in a time shorter than the excitation pulse
Geometry of Information Integration
Information geometry is used to quantify the amount of information
integration within multiple terminals of a causal dynamical system. Integrated
information quantifies how much information is lost when a system is split into
parts and information transmission between the parts is removed. Multiple
measures have been proposed as a measure of integrated information. Here, we
analyze four of the previously proposed measures and elucidate their relations
from a viewpoint of information geometry. Two of them use dually flat manifolds
and the other two use curved manifolds to define a split model. We show that
there are hierarchical structures among the measures. We provide explicit
expressions of these measures
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