167,791 research outputs found
Electron Removal Self Energy and its application to Ca2CuO2Cl2
We propose using the self energy defined for the electron removal Green's
function. Starting from the electron removal Green's function, we obtained
expressions for the removal self energy Sigma^ER (k,omega) that are applicable
for non-quasiparticle photoemission spectral functions from a single band
system. Our method does not assume momentum independence and produces the self
energy in the full k-omega space. The method is applied to the angle resolved
photoemission from Ca_2CuO_2Cl_2 and the result is found to be compatible with
the self energy value from the peak width of sharp features. The self energy is
found to be only weakly k-dependent. In addition, the Im Sigma shows a maximum
at around 1 eV where the high energy kink is located.Comment: 5 pages, 3 figure
Classification of cryptocurrency coins and tokens by the dynamics of their market capitalisations
We empirically verify that the market capitalisations of coins and tokens in
the cryptocurrency universe follow power-law distributions with significantly
different values, with the tail exponent falling between 0.5 and 0.7 for coins,
and between 1.0 and 1.3 for tokens. We provide a rationale for this, based on a
simple proportional growth with birth & death model previously employed to
describe the size distribution of firms, cities, webpages, etc. We empirically
validate the model and its main predictions, in terms of proportional growth
(Gibrat's law) of the coins and tokens. Estimating the main parameters of the
model, the theoretical predictions for the power-law exponents of coin and
token distributions are in remarkable agreement with the empirical estimations,
given the simplicity of the model. Our results clearly characterize coins as
being "entrenched incumbents" and tokens as an "explosive immature ecosystem",
largely due to massive and exuberant Initial Coin Offering activity in the
token space. The theory predicts that the exponent for tokens should converge
to 1 in the future, reflecting a more reasonable rate of new entrants
associated with genuine technological innovations
Universality class of the restricted solid-on-solid model with hopping
We study the restricted solid-on-solid (RSOS) model with finite hopping
distance , using both analytical and numerical methods. Analytically, we
use the hard-core bosonic field theory developed by the authors [Phys. Rev. E
{\bf 62}, 7642 (2000)] and derive the Villain-Lai-Das Sarma (VLD) equation for
the case which corresponds to the conserved RSOS (CRSOS) model
and the Kardar-Parisi-Zhang (KPZ) equation for all finite values of .
Consequently, we find that the CRSOS model belongs to the VLD universality
class and the RSOS models with any finite hopping distance belong to the KPZ
universality class. There is no phase transition at a certain finite hopping
distance contrary to the previous result. We confirm the analytic results using
the Monte Carlo simulations for several values of the finite hopping distance.Comment: 13 pages, 3 figure
Extraction of Singlet States from Noninteracting High-Dimensional Spins
We present a scheme for the extraction of singlet states of two remote
particles of arbitrary quantum spin number. The goal is achieved through
post-selection of the state of interaction mediators sent in succession. A
small number of iterations is sufficient to make the scheme effective. We
propose two suitable experimental setups where the protocol can be implemented.Comment: 4 pages, 2 figure
Entanglement entropy of the composite fermion non-Fermi liquid state
The so-called ``non-Fermi liquid'' behavior is very common in strongly
correlated systems. However, its operational definition in terms of ``what it
is not'' is a major obstacle against theoretical understanding of this
fascinating correlated state. Recently there has been much interest in
entanglement entropy as a theoretical tool to study non-Fermi liquids. So far
explicit calculations have been limited to models without direct experimental
realizations. Here we focus on a two dimensional electron fluid under magnetic
field and filling fraction , which is believed to be a non-Fermi
liquid state. Using the composite fermion (CF) wave-function which captures the
state very accurately, we compute the second R\'enyi entropy using
variational Monte-Carlo technique and an efficient parallel algorithm. We find
the entanglement entropy scales as with the length of the boundary
as it does for free fermions, albeit with a pre-factor twice that of the
free fermion. We contrast the results against theoretical conjectures and
discuss the implications of the results.Comment: 4+ page
Nonlinear coupling of continuous variables at the single quantum level
We experimentally investigate nonlinear couplings between vibrational modes
of strings of cold ions stored in linear ion traps. The nonlinearity is caused
by the ions' Coulomb interaction and gives rise to a Kerr-type interaction
Hamiltonian H = n_r*n_s, where n_r,n_s are phonon number operators of two
interacting vibrational modes. We precisely measure the resulting oscillation
frequency shift and observe a collapse and revival of the contrast in a Ramsey
experiment. Implications for ion trap experiments aiming at high-fidelity
quantum gate operations are discussed
Heisenberg-picture approach to the exact quantum motion of a time-dependent forced harmonic oscillator
In the Heisenberg picture, the generalized invariant and exact quantum
motions are found for a time-dependent forced harmonic oscillator. We find the
eigenstate and the coherent state of the invariant and show that the
dispersions of these quantum states do not depend on the external force. Our
formalism is applied to several interesting cases.Comment: 15 pages, two eps files, to appear in Phys. Rev. A 53 (6) (1996
Hidden AGNs in Early-Type Galaxies
We present a stacking analysis of the complete sample of Early Type Galaxies
(ETGs) in the \textit{Chandra} COSMOS (C-COSMOS) survey, to explore the nature
of the X-ray luminosity in the redshift and stellar luminosity ranges
and {10}^{9}. Using established
scaling relations, we subtract the contribution of X-ray binary populations, to
estimate the combined emission of hot ISM and AGN. To discriminate between the
relative importance of these two components, we (1) compare our results with
the relation observed in the local universe for
hot gaseous halos emission in ETGs, and (2) evaluate the spectral signature of
each stacked bin. We find two regimes where the non-stellar X-ray emission is
hard, consisten t with AGN emission. First, there is evidence of hard, absorbed
X-ray emission in stacked bins including relatively high z () ETGs
with average high X-ray luminosity (L_{X-LMXB}\gtrsim 6\times{10}^{42}\mbox{
erg}/\mbox{s}). These luminosities are consistent with the presence ofhighly
absorbed "hidden" AGNs in these ETGs, which are not visible in their optical-IR
spectra and spectral energy distributions. Second, confirming the early
indication from our C-COSMOS study of X-ray detected ETGs, we find
significantly enhanced X-ray luminoaity in lower stellar mass ETGs
(L_K\lesssim{10}^{11}L_{\astrosun}), relative to the local
relation. The stacked spectra of these ETGs also
suggest X-ray emission harder than expected from gaseous hot halos. This
emission is consistent with inefficient accretion
onto M_{BH}\sim
{10}^{6}-{10}^{8}\,M_{\astrosun}.Comment: 22 pages, 7 figures, 2 tables. Accepted for publications on Ap
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