scholarly journals Modelling of Output Statistics of Single and -Mode Straight and Curved :Ti:LiNb Waveguide Amplifiers

2011 ◽  
Vol 2011 ◽  
pp. 1-6
Author(s):  
Niculae N. Puscas
Keyword(s):  
Photon Number ◽  
Fano Factor ◽  
Optical Quality ◽  
Statistical Fluctuation ◽  
Statistical Parameters ◽  
Transversal Section ◽  
Waveguide Amplifiers ◽  
Power Spectral ◽  
Linear Amplifier ◽  
Small Gain

A theoretical analysis of some statistical parameters which characterize the -doped Ti:LiNbO3 single and -mode straight and curved waveguides is presented in this paper. In the derivation and the evaluation of the spectral optical quality factor, the power spectral density, the Fano factor, the statistical fluctuation, and the spontaneous emission factor we used the small gain approximation, and the photon statistics master equation of the linear amplifier (considering that the photon number distribution is determined by the normalized mode intensity profiles which are not uniform in the transversal section of the waveguide), transposed to the case of straight and curved amplifiers. The simulation results show the evolution of the above-mentioned parameters under various pump regimes and waveguide lengths.

The security of SARG04 protocol in plug and play QKD system with an untrusted source

2012 ◽  
Vol 12 (7&8) ◽  
pp. 630-647
Author(s):  
Bingjie Xu ◽  
Xiang Peng ◽  
Hong Guo
Keyword(s):  
Quantum Key Distribution ◽  
Source Monitoring ◽  
Photon Number ◽  
Key Distribution ◽  
Statistical Fluctuation ◽  
Statistical Parameters ◽  
Plug And Play ◽  
Monitoring Process ◽  
Simulation Results

The SARG04 protocol is one of the most frequently used protocol in commercial plug-and-play quantum key distribution (QKD) system, where an eavesdropper can completely control or change the photon number statistics of the QKD source. To ensure the security of SARG04 protocol in plug-and-play QKD system with an unknown and untrusted source, the bounds of a few statistical parameters of the source need to be monitored. An active or a passive source monitor schemes are proposed to verify these parameters. Furthermore, the practical issues due to statistical fluctuation and detection noise in the source monitoring process are quantitatively analyzed. Our simulation results show that the passive scheme can be efficiently applied to plug-and-play system with SARG04 protocol.

Characterization of Tissue Microstructure Scatterer Distribution with Spectral Correlation

1993 ◽  
Vol 15 (3) ◽  
pp. 238-254 ◽  
Author(s):  
Tomy Varghese ◽  
Kevin D. Donohue
Keyword(s):  
Formation Process ◽  
Biological Tissue ◽  
Statistical Parameters ◽  
Spectral Correlation ◽  
Tissue Microstructure ◽  
Power Spectral ◽  
Spectral Peaks ◽  
Ultrasound Signal

Characterization of tissue microstructure from the backscattered ultrasound signal using the spectral autocorrelation (SAC) function provides information about the scatterer distribution in biological tissue. This paper demonstrates SAC capabilities in characterizing periodicities in A-scans due to regularity in the scatterer distribution. The A-scan is modelled as a cyclostationary signal, where the statistical parameters of the signal vary in time with single or multiple periodicities. This periodicity manifests itself as spectral peaks both in the power spectral density (PSD) and in the SAC. Periodicity in the PSD will produce a well defined dominant peak in the cepstrum, which has been used to determine the scatterer spacing. The relationship between the scatterer spacing and the spacing of the spectral peaks is established using a stochastic model of the echo-formation process from biological tissue. The distribution of the scatterers within the microstructure is modelled using a Gamma function, which offers a flexible method of simulating parametric regularity in the scatterer spacing. Simulations of the tissue microstructure for lower orders of regularity indicate that the SAC components reveal information about the scatterer spacing that are not seen in the PSD and the cepstrum. The echo-formation process is tested by simulating microstructure of varying regularity and analyzing their effect on the SAC, PSD and cepstrum. Experimental validation of the simulation results are provided using in vivo scans of the breast and liver tissue that show the presence of significant spectral correlation components in the SAC.

scholarly journals Generalized Binomial Probability Distributions Attached to Landau Levels on the Riemann Sphere

2011 ◽  
Vol 2011 ◽  
pp. 1-17
Author(s):  
A. Ghanmi ◽  
A. Hafoud ◽  
Z. Mouayn
Keyword(s):  
Coherent States ◽  
Riemann Sphere ◽  
Probability Distributions ◽  
Photon Number ◽  
Landau Levels ◽  
Binomial Probability ◽  
Statistical Parameters ◽  
Generalized Coherent States

A family of generalized binomial probability distributions attached to Landau levels on the Riemann sphere is introduced by constructing a kind of generalized coherent states. Their main statistical parameters are obtained explicitly. As an application, photon number statistics related to coherent states under consideration are discussed.

EVIDENCE FOR A FRACTAL STOCHASTIC PROCESS UNDERLYING MEASLES EPIDEMICS IN BRITAIN

Fractals ◽  
2000 ◽  
Vol 08 (01) ◽  
pp. 29-34 ◽  
Author(s):  
WAYNE S. KENDAL
Keyword(s):  
Stochastic Process ◽  
Time Series ◽  
Spectral Density ◽  
Geometric Distribution ◽  
Fano Factor ◽  
Distribution Histogram ◽  
Power Spectral ◽  
Allan Factor ◽  
Measles Incidence ◽  
Vaccination Period

The variability in measles incidence during the pre-vaccination period of 1944 to 1966, as recorded from 366 communities in England and Wales, was examined for properties of fractal stochastic processes. The power spectral density, Fano factor, and Allan factor were computed from the incidence time-series, and all revealed power-law scaling. As well, the distribution histogram for the weekly incidence approximated a geometric distribution. These features constituted evidence for a fractal stochastic process with underlying geometric statistics at play in the development and resolution of measles epidemics.

STUDY OF SPECTRAL CHARACTERISTICS OF MOTION ARTIFACTS IN AMBULATORY ECG BY ANALYZING PCA RESIDUAL ERRORS

2014 ◽  
Vol 26 (02) ◽  
pp. 1450017
Author(s):  
Rahul Kher ◽  
Tanmay Pawar ◽  
Vishvjit Thakar ◽  
Dipak Patel
Keyword(s):  
Spectral Characteristics ◽  
Principal Component ◽  
Peak Frequency ◽  
Motion Artifacts ◽  
Statistical Parameters ◽  
Ecg Signals ◽  
Ambulatory Ecg ◽  
Power Spectral ◽  
Left And Right ◽  
Residual Errors

In this paper, the spectral characteristics of motion artifacts occurring in an ambulatory ECG signal have been studied using principal component analysis (PCA). The PCA residual errors characterize the spectral behavior of the motion artifacts occurring in ambulatory ECG signals. The ECG signals have been acquired from Biopac MP-36 system and a self-developed wearable ECG recorder. The performance is evaluated by power spectral density (PSD) plots of PCA residual errors as well as statistical parameters like mean, median and variance of PCA errors. The PSD plots clearly indicate that the peak frequency of the motion artifacts occurring due to various body movements (like left and right arms up–down, left and right legs up–down, waist twist, walking and sitting up–down) is located around 20–25 Hz against the ECG peak frequency around 5–10 Hz.

scholarly journals Age-Associated Changes in the Spectral and Statistical Parameters of Surface Electromyogram ofTibialis Anterior

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Ariba Siddiqi ◽  
Sridhar Poosapadi Arjunan ◽  
Dinesh Kant Kumar
Keyword(s):  
Muscle Strength ◽  
Tibialis Anterior ◽  
The Elderly ◽  
Voluntary Contraction ◽  
Maximal Power ◽  
Statistical Parameters ◽  
Surface Electromyogram ◽  
Age Related ◽  
Power Spectral ◽  
Different Levels

Age-related neuromuscular change of Tibialis Anterior (TA) is a leading cause of muscle strength decline among the elderly. This study has established the baseline for age-associated changes in sEMG of TA at different levels of voluntary contraction. We have investigated the use of Gaussianity and maximal power of the power spectral density (PSD) as suitable features to identify age-associated changes in the surface electromyogram (sEMG). Eighteen younger (20–30 years) and 18 older (60–85 years) cohorts completed two trials of isometric dorsiflexion at four different force levels between 10% and 50% of the maximal voluntary contraction. Gaussianity and maximal power of the PSD of sEMG were determined. Results show a significant increase in sEMG’s maximal power of the PSD and Gaussianity with increase in force for both cohorts. It was also observed that older cohorts had higher maximal power of the PSD and lower Gaussianity. These age-related differences observed in the PSD and Gaussianity could be due to motor unit remodelling. This can be useful for noninvasive tracking of age-associated neuromuscular changes.

scholarly journals Bracket states for communication protocols with coherent states

2014 ◽  
Vol 12 (02) ◽  
pp. 1461018 ◽  
Author(s):  
Alessia Allevi ◽  
Stefano Olivares ◽  
Maria Bondani
Keyword(s):  
Coherent States ◽  
Direct Detection ◽  
Photon Number ◽  
Fano Factor ◽  
Local Oscillator ◽  
Input State ◽  
Optical Elements ◽  
Symmetry Properties ◽  
Communication Scheme ◽  
Phase Sensitive

We present the generation and characterization of the class of bracket states, namely phase-sensitive mixtures of coherent states exhibiting symmetry properties in the phase-space description. A bracket state can be seen as the statistical ensemble arriving at a receiver in a typical coherent-state-based communication channel. We show that when a bracket state is mixed at a beam splitter with a local oscillator, both the emerging beams exhibit a Fano factor larger than 1 and dependent on the relative phase between the input state and the local oscillator. We discuss the possibility to exploit this dependence to monitor the phase difference for the enhancement of the performances of a simple communication scheme based on direct detection. Our experimental setup involves linear optical elements and a pair of photon-number-resolving detectors operated in the mesoscopic photon-number domain.

scholarly journals Phase diffusion and the small-noise approximation in linear amplifiers: Limitations and beyond

Quantum ◽  
2019 ◽  
Vol 3 ◽  
pp. 200 ◽  
Author(s):  
Andy Chia ◽  
Michal Hajdušek ◽  
Rosario Fazio ◽  
Leong-Chuan Kwek ◽  
Vlatko Vedral
Keyword(s):  
Signal To Noise Ratio ◽  
Noise Analysis ◽  
Photon Number ◽  
Optical Field ◽  
Signal To Noise ◽  
Small Noise ◽  
Phase Diffusion ◽  
Small Noise Approximation ◽  
Linear Amplifier ◽  
Phase Uncertainty

The phase of an optical field inside a linear amplifier is widely known to diffuse with a diffusion coefficient that is inversely proportional to the photon number. The same process occurs in lasers which limits its intrinsic linewidth and makes the phase uncertainty difficult to calculate. The most commonly used simplification is to assume a narrow photon-number distribution for the optical field (which we call the small-noise approximation). For coherent light, this condition is determined by the average photon number. The small-noise approximation relies on (i) the input to have a good signal-to-noise ratio, and (ii) that such a signal-to-noise ratio can be maintained throughout the amplification process. Here we ask: For a coherent input, how many photons must be present in the input to a quantum linear amplifier for the phase noise at the output to be amenable to a small-noise analysis? We address these questions by showing how the phase uncertainty can be obtained without recourse to the small-noise approximation. It is shown that for an ideal linear amplifier (i.e. an amplifier most favourable to the small-noise approximation), the small-noise approximation breaks down with only a few photons on average. Interestingly, when the input strength is increased to tens of photons, the small-noise approximation can be seen to perform much better and the process of phase diffusion permits a small-noise analysis. This demarcates the limit of the small-noise assumption in linear amplifiers as such an assumption is less true for a nonideal amplifier.

High latitude ionospheric scintillations

1984 ◽  
Vol 62 (5) ◽  
pp. 487-504 ◽  
Author(s):  
J. A. Fulford ◽  
P. A. Forsyth
Keyword(s):  
Statistical Parameter ◽  
Spectral Density Function ◽  
Statistical Characteristics ◽  
Angle Of Arrival ◽  
Statistical Parameters ◽  
Application Systems ◽  
Power Spectral ◽  
Radio Signals ◽  
Ionospheric Scintillations

The statistical characteristics of ionospheric irregularities are often described by specifying one or two of the statistical parameters of the scintillations that the irregularities produce in satellite radio signals. The most commonly used parameter for this purpose is the spectral index (slope of the power spectral density function on a log–log plot). While it is becoming increasingly clear that the characterization of either phase or amplitude scintillations by a single parameter may obscure significant characteristics of the scintillations, this simple approach has proven to be useful for the prediction of the behaviour of transionospheric propagation paths such as those used in various space application systems. This paper explores the use, in addition to the usual phase and amplitude observations, of measurements of angle-of-arrival, in order to characterize the scintillations. Since each of these observations represent a different kind of observational "filtering", the combination of one statistical parameter from each type of measurement should provide a more adequate characterization of the scintillations. It is found that the use of the widths of the autocorrelation functions for this purpose is preferred over the use of spectral indices.

Sign in / Sign up

Export Citation Format

Share Document