41,832 research outputs found
Variational study of the one dimensional t-J model
We find the Gutzwiller projected Fermi sea wave function(GWF) has the correct
phase structure to describe the kink nature of the doped holes in the ground
state of the one dimensional model. We find the failure of the GWF for
general value of and electron density can be attributed to the
residual charge correlation in the ground state. We find such residual charge
correlation is well described by a XXZ-type effective Hamiltonian. Based on
these observations, a Pfaffian-type variational wave function is proposed and
is found to reproduce correctly the global phase diagram and corresponding
correlation functions of the one dimensional model, including the
Luther-Emery phase in the low electron density and large region.Comment: 8 pages, 8 figure
Spin Charge Recombination in Projected Wave Functions
We find spin charge recombination is a generic feature of projected wave
functions. We find this effect is responsible for a series of differences
between mean field theory prediction and the result from projected wave
functions. We also find spin charge recombination plays an important role in
determining the dissipation of supercurrent, the quasiparticle properties and
the hole - hole correlation.Comment: 13 pages,7 figure
The Hellberg-Mele Jastrow factor as a variational wave function for the one dimensional XXZ model
We find the Jastrow factor introduced by Hellberg and Mele in their study of
the one dimensional t-J model provides an exceedingly good variational
description of the one dimensional XXZ model.Comment: 3 pages, 2 figure
Topological Order in Projected Wave Functions and Effective Theories of Quantum Antiferromagnets
We study the topological order in RVB state derived from Gutzwiller
projection of BCS-like mean field state. We propose to construct the
topological excitation on the projected RVB state through Gutzwiller projection
of mean field state with inserted flux tube. We prove that all
projected RVB states derived from bipartite effective theories, no matter the
gauge structure in the mean field ansatz, are positive definite in the sense of
the Marshall sign rule, which provides a universal origin for the absence of
topological order in such RVB state.Comment: 5 pages, 1 figure
Nonlinear reconstruction of redshift space distortions
We apply nonlinear reconstruction to the dark matter density field in
redshift space and solve for the nonlinear mapping from the initial Lagrangian
position to the final redshift space position. The reconstructed anisotropic
field inferred from the nonlinear displacement correlates with the linear
initial conditions to much smaller scales than the redshift space density
field. The number of linear modes in the density field is improved by a factor
of 30-40 after reconstruction. We thus expect this reconstruction approach to
substantially expand the cosmological information including baryon acoustic
oscillations and redshift space distortions for dense low-redshift large scale
structure surveys including for example SDSS main sample, DESI BGS, and 21 cm
intensity mapping surveys.Comment: 18 pages, 21 figures, published version. The nonlinear reconstruction
code is available at https://github.com/ColdThunder/NR-cod
Double Electromagnetically Induced Transparency in a Tripod-type Atom System
The electromagnetically induced transparency (EIT) phenomenon in a four level
atomic system with tripod configuration is studied. The results show that this
configuration is equivalent to the combination of two single three-level
configurations, which, under certain conditions, results in the
so-called double-EIT (DEIT) phenomenon. The properties of the double
transparency windows for DEIT are discussed in detail and the possible
experimental scheme is proposed.Comment: 5 pages, and 8 figure
HYPE: A High Performing NLP System for Automatically Detecting Hypoglycemia Events from Electronic Health Record Notes
Hypoglycemia is common and potentially dangerous among those treated for
diabetes. Electronic health records (EHRs) are important resources for
hypoglycemia surveillance. In this study, we report the development and
evaluation of deep learning-based natural language processing systems to
automatically detect hypoglycemia events from the EHR narratives. Experts in
Public Health annotated 500 EHR notes from patients with diabetes. We used this
annotated dataset to train and evaluate HYPE, supervised NLP systems for
hypoglycemia detection. In our experiment, the convolutional neural network
model yielded promising performance in a 10-fold cross-validation setting. Despite the
annotated data is highly imbalanced, our CNN-based HYPE system still achieved a
high performance for hypoglycemia detection. HYPE could be used for EHR-based
hypoglycemia surveillance and to facilitate clinicians for timely treatment of
high-risk patients.Comment: Machine Learning for Health (ML4H) Workshop at NeurIPS 2018
arXiv:1811.0721
Meson spectrum in Regge phenomenology
Under the assumption that both light and heavy quarkonia populate
approximately linear Regge trajectories with the requirements of additivity of
intercepts and inverse slopes, the masses of different meson multiplets are
estimated. The predictions derived from the quasi-linear Regge trajectories are
in reasonable agreement with those given by many other references.Comment: 21 pages, to appear in Eur. Phys. J.
Entanglement Criterion for Coherent Subtraction and Coherent Addition Bipartite Continuous variable States
Photon subtraction and addition are experimental means of generating
non-Gaussian states from Gaussian states. Coherent subtraction or addition is a
combination of photon subtractions or additions. The resultant states are quite
general non-Gaussian states. The states can be photon number entangled states
with arbitrary coefficients. We derive the entanglement conditions for several
classes of coherent subtraction or coherent addition bipartite continuous
variable states. One of the entanglement conditions is necessary and
sufficient.Comment: 6 page
Cosmic Reionization Study : Principle Component Analysis After Planck
The study of reionization history plays an important role in understanding
the evolution of our universe. It is commonly believed that the intergalactic
medium (IGM) in our universe are fully ionized today, however the reionizing
process remains to be mysterious. A simple instantaneous reionization process
is usually adopted in modern cosmology without direct observational evidence.
However, the history of ionization fraction, will influence cosmic
microwave background (CMB) observables and constraints on optical depth .
With the mocked future data sets based on featured reionization model, we find
the bias on introduced by instantaneous model can not be neglected. In
this paper, we study the cosmic reionization history in a model independent
way, the so called principle component analysis (PCA) method, and reconstruct
at different redshift with the data sets of Planck, WMAP 9 years
temperature and polarization power spectra, combining with the baryon acoustic
oscillation (BAO) from galaxy survey and type Ia supernovae (SN) Union 2.1
sample respectively. The results show that reconstructed is consistent
with instantaneous behavior, however, there exists slight deviation from this
behavior at some epoch. With PCA method, after abandoning the noisy modes, we
get stronger constraints, and the hints for featured evolution could
become a little more obvious.Comment: 12 pages, 10 figure
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