27,012 research outputs found
Classical Optimizers for Noisy Intermediate-Scale Quantum Devices
We present a collection of optimizers tuned for usage on Noisy Intermediate-Scale Quantum (NISQ) devices. Optimizers have a range of applications in quantum computing, including the Variational Quantum Eigensolver (VQE) and Quantum Approximate Optimization (QAOA) algorithms. They are also used for calibration tasks, hyperparameter tuning, in machine learning, etc. We analyze the efficiency and effectiveness of different optimizers in a VQE case study. VQE is a hybrid algorithm, with a classical minimizer step driving the next evaluation on the quantum processor. While most results to date concentrated on tuning the quantum VQE circuit, we show that, in the presence of quantum noise, the classical minimizer step needs to be carefully chosen to obtain correct results. We explore state-of-the-art gradient-free optimizers capable of handling noisy, black-box, cost functions and stress-test them using a quantum circuit simulation environment with noise injection capabilities on individual gates. Our results indicate that specifically tuned optimizers are crucial to obtaining valid science results on NISQ hardware, and will likely remain necessary even for future fault tolerant circuits
Dynamic behavior of porous electrode systems final report
Mathematical model of flooded porous electrodes under dynamic and static conditions - Methods for measuring porous electrode reaction distributio
Mortality Model for a Perennial Grass in Australian Semi-Arid Wooded Grasslands Grazed by Sheep
Grazing of sheep in marginal semi-arid environments is risky because grazing appears to predispose grass plants, especially palatable species, to sudden death (Hodgkinson, 1994; 1995). These early observations were based on a preliminary analysis of perennial grass survival in a single drought and supported the concept of tactical grazing proposed by Westoby et al. (1989) as a preferred management. Later this idea was developed by suggesting the existence of critical thresholds for perennial grass survival, which when crossed, collapses grass populations (Hodgkinson, 1994). Here we examine the relationship between mortality of a palatable perennial grass, Thyridolepis mitchelliana, and a number of variables measured during a 10-year period
Bulk and Brane Decay of a (4+n)-Dimensional Schwarzschild-De-Sitter Black Hole: Scalar Radiation
In this paper, we extend the idea that the spectrum of Hawking radiation can
reveal valuable information on a number of parameters that characterize a
particular black hole background - such as the dimensionality of spacetime and
the value of coupling constants - to gain information on another important
aspect: the curvature of spacetime. We investigate the emission of Hawking
radiation from a D-dimensional Schwarzschild-de-Sitter black hole emitted in
the form of scalar fields, and employ both analytical and numerical techniques
to calculate greybody factors and differential energy emission rates on the
brane and in the bulk. The energy emission rate of the black hole is
significantly enhanced in the high-energy regime with the number of spacelike
dimensions. On the other hand, in the low-energy part of the spectrum, it is
the cosmological constant that leaves a clear footprint, through a
characteristic, constant emission rate of ultrasoft quanta determined by the
values of black hole and cosmological horizons. Our results are applicable to
"small" black holes arising in theories with an arbitrary number and size of
extra dimensions, as well as to pure 4-dimensional primordial black holes,
embedded in a de Sitter spacetime.Comment: 31 pages, latex file, data files available at
http://lpsc.in2p3.fr/ams/greybody/ some clarifying comments and references
added, typos corrected, version to appear in Phys. Rev.
Exact Results for Evaporating Black Holes in Curvature-Squared Lovelock Gravity: Gauss-Bonnet Greybody Factors
Lovelock gravity is an important extension of General Relativity that
provides a promising framework to study curvature corrections to the Einstein
action, while avoiding ghosts and keeping second order field equations. This
paper derives the greybody factors for D-dimensional black holes arising in a
theory with a Gauss-Bonnet curvature-squared term. These factors describe the
non-trivial coupling between black holes and quantum fields during the
evaporation process: they can be used both from a theoretical viewpoint to
investigate the intricate spacetime structure around such a black hole, and for
phenomenological purposes in the framework of braneworld models with a low
Planck scale. We derive exact spectra for the emission of scalar, fermion and
gauge fields emitted on the brane, and for scalar fields emitted in the bulk,
and demonstrate how the Gauss-Bonnet term can change the bulk-to-brane emission
rates ratio in favour of the bulk channel in particular frequency regimes.Comment: 29 pages, Latex file, 11 figures, Data files (greybody factors)
available at http://lpsc.in2p3.fr/ams/greybody/, typos corrected, references
added, version to appear in Phys. Rev.
Tracking system analytic calibration activities for the Mariner Mars 1969 mission
Calibration activity of Deep Space Network in support of Mars encounter phase of Mariner Mars 1969 missio
Near Infrared Spectra of Type Ia Supernovae
We report near infrared (NIR) spectroscopic observations of twelve
``Branch-normal'' Type Ia supernovae (SNe Ia) which cover the wavelength region
from 0.8-2.5 microns. Our sample more than doubles the number of SNe Ia with
published NIR spectra within three weeks of maximum light. The epochs of
observation range from thirteen days before maximum light to eighteen days
after maximum light. A detailed model for a Type Ia supernovae is used to
identify spectral features. The Doppler shifts of lines are measured to obtain
the velocity and, thus, the radial distribution of elements.
The NIR is an extremely useful tool to probe the chemical structure in the
layers of SNe Ia ejecta. This wavelength region is optimal for examining
certain products of the SNe Ia explosion that may be blended or obscured in
other spectral regions. We identify spectral features from MgII, CaII, SiII,
FeII, CoII, NiII and possibly MnII. We find no indications for hydrogen, helium
or carbon in the spectra. The spectral features reveal important clues about
the physical characteristics of SNe Ia. We use the features to derive upper
limits for the amount of unburned matter, to identify the transition regions
from explosive carbon to oxygen burning and from partial to complete silicon
burning, and to estimate the level of mixing during and after the explosion.Comment: 44 pages, 7 figures, 3 tables, accepted by Ap
Amino Acid and Protein Requirements of Layers
Studies on this problem have taken two approaches, one using a 9.4% protein basal diet supplemented with 0.19% lysine, 0.25% DL-methionine and 0.04% DL-tryptophane and the other comparing a 14% protein plus methionine diet with a typical 16% protein diet
A Comparison of Slat Floors, Litter Floors and Cages for Laying Hens
Commercial hybrid pullets were distributed in 3 different buildings at 20 weeks of age and fed similar diets. Twelve slat floor pens in a building referred to as the environment house and 2 litter floor pens in a building referred to as the brooder house each received 140 pullets (1 bird/sq. ft.)- Six pullets were placed in each of 32 cages in a cage layer house
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