1,850 research outputs found
Loss-resistant unambiguous phase measurement
Entangled multi-photon states have the potential to provide improved
measurement accuracy, but are sensitive to photon loss. It is possible to
calculate ideal loss-resistant states that maximize the Fisher information, but
it is unclear how these could be experimentally generated. Here we propose a
set of states that can be obtained by processing the output from parametric
down-conversion. Although these states are not optimal, they provide
performance very close to that of optimal states for a range of parameters.
Moreover, we show how to use sequences of such states in order to obtain an
unambiguous phase measurement that beats the standard quantum limit. We
consider the optimization of parameters in order to minimize the final phase
variance, and find that the optimum parameters are different from those that
maximize the Fisher information.Comment: 8 pages, 7 figures, comments are welcom
Quantum noise in second generation, signal-recycled laser interferometric gravitational-wave detectors
It has long been thought that the sensitivity of laser interferometric
gravitational-wave detectors is limited by the free-mass standard quantum
limit, unless radical redesigns of the interferometers or modifications of
their input/output optics are introduced. Within a fully quantum-mechanical
approach we show that in a second-generation interferometer composed of arm
cavities and a signal recycling cavity, e.g., the LIGO-II configuration, (i)
quantum shot noise and quantum radiation-pressure-fluctuation noise are
dynamically correlated, (ii) the noise curve exhibits two resonant dips, (iii)
the Standard Quantum Limit can be beaten by a factor of 2, over a frequency
range \Delta f/f \sim 1, but at the price of increasing noise at lower
frequencies.Comment: 35 pages, 9 figures; few misprints corrected and some references
adde
Application of the Progressive Wavelet Correlation in Image Retrieving
In the paper we apply progressive wavelet correlation along with Fourier methods for searching and retrieving images stored in a database. The searching consists of three incremental steps, each of which quadruples the number of correlation points. The process can be halted at any stage if the intermediate results indicate that the correlation will not result in a match. We perform a series of image
search experiments that cover the following scenarios:
(A) the given image is present in the database; (B) copies of the given image are present but with different names; (C) similar (but not identical) images are present; and (D) the given image is not present. Experiments are performed with data bases up to 1000 images, using the Oracle database and the Matlab component Database Toolbox for operations with
databases
Mathematical framework for simulation of quantum fields in complex interferometers using the two-photon formalism
We present a mathematical framework for simulation of optical fields in
complex gravitational-wave interferometers. The simulation framework uses the
two-photon formalism for optical fields and includes radiation pressure
effects, an important addition required for simulating signal and noise fields
in next-generation interferometers with high circulating power. We present a
comparison of results from the simulation with analytical calculation and show
that accurate agreement is achieved
Sub-SQL Sensitivity via Optical Rigidity in Advanced LIGO Interferometer with Optical Losses
The ``optical springs'' regime of the signal-recycled configuration of laser
interferometric gravitational-wave detectors is analyzed taking in account
optical losses in the interferometer arm cavities. This regime allows to obtain
sensitivity better than the Standard Quantum Limits both for a free test mass
and for a conventional harmonic oscillator. The optical losses restrict the
gain in sensitivity and achievable signal-to-noise ratio. Nevertheless, for
parameters values planned for the Advanced LIGO gravitational-wave detector,
this restriction is insignificant.Comment: 15 pages, 9 figure
Map online system using internet-based image catalogue
Digital maps carry along its geodata information such as coordinate that is important in one particular topographic and thematic map. These geodatas are meaningful especially in military field. Since the maps carry along this information, its makes the size of the images is too big. The bigger size, the bigger storage is required to allocate the image file. It also can cause longer loading time. These conditions make it did not suitable to be applied in image catalogue approach via internet environment. With compression techniques, the image size can be reduced and the quality of the image is still guaranteed without much changes. This report is paying attention to one of the image compression technique using wavelet technology. Wavelet technology is much batter than any other image compression technique nowadays. As a result, the compressed images applied to a system called Map Online that used Internet-based Image Catalogue approach. This system allowed user to buy map online. User also can download the maps that had been bought besides using the searching the map. Map searching is based on several meaningful keywords. As a result, this system is expected to be used by Jabatan Ukur dan Pemetaan Malaysia (JUPEM) in order to make the organization vision is implemented
Large-Scale Optical Neural Networks based on Photoelectric Multiplication
Recent success in deep neural networks has generated strong interest in
hardware accelerators to improve speed and energy consumption. This paper
presents a new type of photonic accelerator based on coherent detection that is
scalable to large () networks and can be operated at high (GHz)
speeds and very low (sub-aJ) energies per multiply-and-accumulate (MAC), using
the massive spatial multiplexing enabled by standard free-space optical
components. In contrast to previous approaches, both weights and inputs are
optically encoded so that the network can be reprogrammed and trained on the
fly. Simulations of the network using models for digit- and
image-classification reveal a "standard quantum limit" for optical neural
networks, set by photodetector shot noise. This bound, which can be as low as
50 zJ/MAC, suggests performance below the thermodynamic (Landauer) limit for
digital irreversible computation is theoretically possible in this device. The
proposed accelerator can implement both fully-connected and convolutional
networks. We also present a scheme for back-propagation and training that can
be performed in the same hardware. This architecture will enable a new class of
ultra-low-energy processors for deep learning.Comment: Text: 10 pages, 5 figures, 1 table. Supplementary: 8 pages, 5,
figures, 2 table
Quantum Measurement Theory in Gravitational-Wave Detectors
The fast progress in improving the sensitivity of the gravitational-wave (GW)
detectors, we all have witnessed in the recent years, has propelled the
scientific community to the point, when quantum behaviour of such immense
measurement devices as kilometer-long interferometers starts to matter. The
time, when their sensitivity will be mainly limited by the quantum noise of
light is round the corner, and finding the ways to reduce it will become a
necessity. Therefore, the primary goal we pursued in this review was to
familiarize a broad spectrum of readers with the theory of quantum measurements
in the very form it finds application in the area of gravitational-wave
detection. We focus on how quantum noise arises in gravitational-wave
interferometers and what limitations it imposes on the achievable sensitivity.
We start from the very basic concepts and gradually advance to the general
linear quantum measurement theory and its application to the calculation of
quantum noise in the contemporary and planned interferometric detectors of
gravitational radiation of the first and second generation. Special attention
is paid to the concept of Standard Quantum Limit and the methods of its
surmounting.Comment: 147 pages, 46 figures, 1 table. Published in Living Reviews in
Relativit
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