2,952 research outputs found
Relative resilience to noise of standard and sequential approaches to measurement-based quantum computation
A possible alternative to the standard model of measurement-based quantum
computation (MBQC) is offered by the sequential model of MBQC -- a particular
class of quantum computation via ancillae. Although these two models are
equivalent under ideal conditions, their relative resilience to noise in
practical conditions is not yet known. We analyze this relationship for various
noise models in the ancilla preparation and in the entangling-gate
implementation. The comparison of the two models is performed utilizing both
the gate infidelity and the diamond distance as figures of merit. Our results
show that in the majority of instances the sequential model outperforms the
standard one in regard to a universal set of operations for quantum
computation. Further investigation is made into the performance of sequential
MBQC in experimental scenarios, thus setting benchmarks for possible cavity-QED
implementations.Comment: 11 pages, 11 figures; close to published versio
Income Inequality, Incarceration, and Black-White Poverty Rate Differentials
This paper attempts to analyze and isolate the effects of income inequality on the difference between poverty rates amongst the Black and White population by state in 2010, using each state’s GINI coefficient estimate as the inequality measurement. In addition, the author proposes an alternative income distribution measurement to try and further interpret the effects of a particular state’s income allocation on its poverty rate differential. This paper will also discuss, and attempt to quantify, other factors that could affect disparity in poverty rates between Black and White Americans, such as incarceration rates. The author finds that there is some evidence that a higher state GINI coefficient corresponded with a smaller magnitude of difference between Black and White poverty rates, while a higher variance in allocation amongst income brackets corresponded with an increase in the magnitude of the poverty rate differential
A Generalized Semi-Analytic Model for Magnetar-Driven Supernovae
Several types of energetic supernovae, such as superluminous supernovae
(SLSNe) and broad-line Ic supernovae (Ic-BL SNe), could be powered by the
spin-down of a rapidly rotating magnetar. Currently, most models used to infer
the parameters for potential magnetar-driven supernovae make several unsuitable
assumptions that likely bias the estimated parameters. In this work, we present
a new model for magnetar-driven supernovae that relaxes several of these
assumptions and an inference workflow that enables accurate estimation of
parameters from lightcurves of magnetar-driven supernovae. In particular, in
this model, we include the dynamical evolution of the ejecta, coupling it to
the energy injected by the magnetar itself while also allowing for non-dipole
spin down. We show that the model can reproduce SLSN and Ic-BL SN light curves
consistent with the parameter space from computationally expensive numerical
models. We also show the results of parameter inference on four well-known
example supernovae, demonstrating the model's effectiveness at capturing the
considerable diversity in magnetar-driven supernova lightcurves. The model fits
each light curve well and recovers parameters broadly consistent with previous
works. This model will allow us to explore the full diversity of
magnetar-driven supernovae under one theoretical framework, more accurately
characterize these supernovae from only photometric data, and make more
accurate predictions of future multiwavelength emission to test the
magnetar-driven scenario better.Comment: 16 pages, 12 pages including appendices. Submitted to MNRAS. Comments
welcome. Model available in public code Redback:
https://github.com/nikhil-sarin/redbac
Towards Nebular Spectral Modeling of Magnetar-Powered Supernovae
Many energetic supernovae are thought to be powered by the rotational-energy
of a highly-magnetized, rapidly-rotating neutron star. The emission from the
associated luminous pulsar wind nebula (PWN) can photoionize the supernova
ejecta, leading to a nebular spectrum of the ejecta with signatures possibly
revealing the PWN. SN 2012au is hypothesized to be one such supernova. We
investigate the impact of different ejecta and PWN parameters on the supernova
nebular spectrum, and test if any photoionization models are consistent with SN
2012au. We study how constraints from the nebular phase can be linked into
modelling of the diffusion phase and the radio emission of the magnetar. We
present a suite of late-time (1-6y) spectral simulations of SN ejecta powered
by an inner PWN. Over a large grid of 1-zone models, we study the behaviour of
the SN physical state and line emission as PWN luminosity (),
injection SED temperature (), ejecta mass (), and
composition (pure O or realistic) vary. We discuss the resulting emission in
the context of the observed behaviour of SN 2012au, a strong candidate for a
PWN-powered SN. The supernova nebular spectrum varies as varies,
as the ejecta become less ionized as increases. Low ejecta mass
models at high PWN power obtain runaway ionization for O I and, in extreme
cases, also O II, causing a sharp decrease in their ion fraction over a small
change in the parameter space. Certain models can reproduce the oxygen lines
luminosities of SN 2012au reasonably well at individual epochs, but we find no
model that fits over the whole time evolution; this is likely due to the simple
model setup. Using our derived constraints from the nebular phase, we predict
that the magnetar powering SN 2012au had an initial rotation period 15
ms, and should be a strong radio source (F > 100 mJy) for decades.Comment: 26 pages, 22 figures, submitted to A&A. Comments welcom
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