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Kinetic theory of shot noise in nondegenerate diffusive conductors

Kinetic theory of shot noise in nondegenerate diffusive conductors

We investigate current fluctuations in nondegenerate semiconductors, on length scales intermediate between the elastic and inelastic mean free paths. We present an exact solution of the nonlinear kinetic equations in the regime of space-charge limited conduction, without resorting to the drift approximation of previous work. By including the effects of a finite voltage and carrier density in the contact region, a quantitative agreement is obtained with Monte Carlo simulations by Gonza´lez et al., for a model of an energy-independent elastic scattering rate. The shot-noise power P is suppressed below the Poisson value P Poisson ⫽ 2e I ¯ 共 at mean current
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Noise Specs Confusing

Noise Specs Confusing

It’s really all very simpleÐonce you understand it. Then, here’s the inside story on noise for those of us who haven’t been designing low noise amplifiers for ten years. You hear all sorts of terms like signal-to-noise ratio, noise figure, noise factor, noise voltage, noise current, noise pow- er, noise spectral density, noise per root Hertz, broadband noise, spot noise, shot noise, flicker noise, excess noise, I/F noise, fluctuation noise, thermal noise, white noise, pink noise, popcorn noise, bipolar spike noise, low noise, no noise, and loud noise. No wonder not everyone understands noise specifications.
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Plasmonic field confinement for separate absorption-multiplication in InGaAs nanopillar avalanche photodiodes

Plasmonic field confinement for separate absorption-multiplication in InGaAs nanopillar avalanche photodiodes

Excess noise. The excess noise was measured by illuminating the APD with a 1064nm laser (Orbits Lightwave Ethernal SlowLight) with shot noise limited RIN and measuring the noise power spectral density with a network signal analyzer (Stanford Research Systems SR780) at 100 kHz, well above 1/f noise. DC bias was applied through a bias tee using a low noise power supply (Agilent B2961A) and ultra low noise filter (Agilent N1294A-021). The impedance for conversion of power spectral density to current spectral density was measured by first measuring the DC photocurent at a given optical power, then modulating the laser at 5 kHz and measuring the power spectral density at 5 kHz with the signal analyzer. Assuming the peak-to-peak current is equal to the DC current, the impedance can easily be calculated. The amplifier and dark current noise was measured and subtracted from the APD noise under illumination. Gain vs. incident power was measured to ensure gain saturation does not occur at the incident optical power used for the excess noise measurement.
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Quantum shot noise

Quantum shot noise

wire. At Iow currents, the black curve shows the noise satu- rate at the level set by the temperature of 0.3 K. Otherwise, the linear relation between noise power and current is the sign[r]

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Pricing basket default swaps in a tractable shot-noise model

Pricing basket default swaps in a tractable shot-noise model

Abstract. We value CDS spreads and k th-to-default swap spreads in a tractable shot noise model. The default dependence is modelled by letting the individual jumps of the default intensity be driven by a common latent factor. The arrival of the jumps is driven by a Poisson process. By using conditional independence and properties of the shot noise processes we derive tractable closed-form expressions for the default distribution and the ordered survival distributions in a homogeneous portfolio. These quantities are then used to price and study CDS spreads and k th-to-default swap spreads as function of the model parameters. We study the k th-to-default spreads as function of the CDS spread, as well as other parameters in the model. All calibrations lead to perfect fits.
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Anomalous non-linear shot noise at high voltage bias

Anomalous non-linear shot noise at high voltage bias

Conclusion and Outlook. In conclusion, we have performed shot-noise measurements over Au single atom point contacts in the nonlinear regime, even up to 800 mV bias as shown in the third example in Figure 3. These shot noise data show highly nonlinear behavior with applied bias, which has no specific trend and which is different for every different contact. We have shown that these nonlinearities arise due to quantum interference of electronic waves which take multiple paths due to elastic scattering on the defects present in the leads close to the point contact. This makes the transmission probability of the contact energy and voltage dependent, which means that usual assumptions based on the linear regime break down. We can qualitatively explain the main features in the measured nonlinearity. For a fully quantitative description other energy and voltage dependent e ff ects need to be considered due to the intrinsic transmission of the point contact itself, the e ff ect of other channels and the voltage drop over the defect sites. Any inelastic e ff ects, including non- equilibrium phonon back action and backscattering of electrons which could lower the junction conductance is also not included in the model. We have presented experimental data where the nonlinearity is such that the shot noise even decreases with increase in bias. The results presented here suggest control over the position of defects in the vicinity of
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Modified Boundary Discriminative Noise Detection and Removal Technique for Salt and Pepper Noise Removal

Modified Boundary Discriminative Noise Detection and Removal Technique for Salt and Pepper Noise Removal

Many denoising schemes are ―decision-based‖ median filters this means that the noise candidates are first detected by some rules and are replaced by the median output or its variants. For instance, in decision based filter (DBA) [6] & improved decision based filter (IDBA) [7], the noise candidate is replaced by median or mean of neighboring pixels. These schemes are good because the uncorrupted pixels will not be modified. However, the replacement methods in these denoising schemes cannot preserve the features of the images; in particular the edges are smeared. In contrast, Boundary discriminative Noise detection can preserve edges during denoising but it uses 21x21 huge window size followed by 3x3 window size for noise detection that require more processing time & its filtering process is complicated.
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Corrosion Behavior of SS-304 in NaCl Solution at Different Temperatures Using Electrochemical Noise Technique

Corrosion Behavior of SS-304 in NaCl Solution at Different Temperatures Using Electrochemical Noise Technique

and shot noise analysis results showed that the corrosion rate of SS-304 also increased as temperature increased, but the degree of corrosion rate increasing was different obviously during different temperature ranges. In addition, increasing temperature changed the corrosion type of SS-304 from passivation to pitting. Wavelet analysis provided more details about the corrosion process. The analysis results showed that at 20 0 C SS-304 would experience passivation and metastable pitting process for a long time. When temperature increased to 40 0 C, 60 0 C and 80 0 C, passivation and metastable pitting process got shorter greatly, which may be caused by the change of passivation film property and the acceleration of electrochemical reaction at high temperature. Finally, the EN analysis results were verified by the corrosion morphologies obtained from optical microscope.
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The Effects of Shot Peening Treatment on the Corrosion Rate of HQ 805 Machinery Steel

The Effects of Shot Peening Treatment on the Corrosion Rate of HQ 805 Machinery Steel

resistance [13]. Shot peening is a cheap conventional surface treatment which can be used for components with complex geometry [14]. Shot peening process is commonly used to improve surface characteristic and is a promising method to improve mechanical properties and characteristics of the surface, and also efficient to improve physical quality of the metal [9,14,15]. Shot peening is able to induce compressive residual stress on material surface film which causes surface hardened [16]. Surface hardened is needed to increase material resistance to corrosion. Shot peening treatment also resulted in nanocrystalline film which is useful in forming thin film which is protective. Thin film formation on material surface contributes to the increase of corrosion resistance [17].
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An Improved Balanced Optical Phase-Locked Loop Incorporating an Electro-Optic Phase Modulator

An Improved Balanced Optical Phase-Locked Loop Incorporating an Electro-Optic Phase Modulator

ABSTRACT: A balanced optical phase-locked loop (OPLL) has been investigated through simulation experiment, considering the photo-detector shot noise, laser phase noise and loop propagation delay into account. This optical balanced loop contains an additional electro-optic phase modulator in the phase-locking branch to improve the tracking capability of the loop. The tracking behaviour of the OPLL are investigated in terms of pull-in behaviour and phase- error variance in presence of loop-delay. The modified loop achieves lock-in state in a relatively smaller acquisition time than the conventional OPLL. In this OPLL, the line-width requirement can be easily increased to a large value, by changing the phase control parameter.
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Density-matrix simulation of small surface codes under current and projected experimental noise

Density-matrix simulation of small surface codes under current and projected experimental noise

Dephasing of fl ux-pulsed qubits. During the coherent step, transmons are repeatedly moved in frequency away from their sweetspot using fl ux pulses, either to implement a C-Z gate or to avoid one. Away from the sweetspot, transmons become fi rst-order sensitive to fl ux noise, which causes an additional random phase shift. As this noise typically has a 1/f power spectrum, the largest contribution comes from low-frequency components that are essentially static for a single run, but fl uctuating between different runs. In our simulation, we approximate the effect of this noise through ensemble averaging, with quasi-static phase error added to a transmon whenever it is fl ux pulsed. Gaussian phase errors with the variance (calculated in Supplemental Material) are drawn independently for each qubit and for each run.
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Theoretical Foundations for Quantum Measurement in a General Relativistic Framework

Theoretical Foundations for Quantum Measurement in a General Relativistic Framework

A natural question to ask is then how well we can isolate a system from the environ- ment. Can we systematically identify and shield our system from external dof’s, and if so, is the lack of superimposed cats simply the result of non-optimal experimental conditions? For many physicists, this scenario seems implausible enough to moti- vate the search for fundamental decoherence mechanisms that cannot be eliminated even in the ideal case. For this purpose, gravity holds great appeal. For one, grav- itational forces scales with mass and is therefore consistent with our intuition that macroscopic objects are classical. Additionally, Einstein’s theory of gravity as the curvature of spacetime is not an environment that can be controlled or eliminated, and is therefore a natural candidate for a universally decohering mechanism. Intimately related to decoherence is quantum measurement, which in our use refers to precision measurements of classical variables using quantum limited devices, where measurement errors are attributed to quantum uncertainty. Understanding and controlling quantum noise has enabled the detection of minute signals that can have drastic implications for our understanding of physics, nature, and the universe, with one of the most important examples to date being LIGO’s detection of gravitational waves [1]. In terms of quantum noise properties, LIGO (Laser Interferometer Gravitational-Wave Observatory) is in essence an optomechanical system which detects perturbations in spacetime, and whose detections have been consistent with Einstein’s theory of general relativity. Beyond observing astrophysical events in the far reaches of our universe, there is also hope of using LIGO to probe the nature of gravity and constrain alternative theories for clues in the search for a theory of everything.
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Dispersive detection of radio frequency dressed states

Dispersive detection of radio frequency dressed states

propagate through the atomic ensemble. A half-wave plate allows us to co-rotate the planes of polarization with respect to the coordinate axes, typically adjusted to ± 45° orientation. To observe the adiabatic dressing process, the detection beams can be active during the magnetic field ramps. For state detection, we let the magnetic field amplitudes reach constant values before the two lasers are pulsed either consecutively or, in some circumstances, simultaneously as detailed below. Upon interaction with the atoms, the beams become ellipti- cally polarized, where the ellipticity or phase shift be- tween π- and σ-polarized components is proportional to the atomic density in the respective states. The phase shift is measured polarimetrically with a circular ana- lyzer comprising a quarter-wave plate, a Wollaston prism, a balanced photodetector pair (Thorlabs PDB210A) and an optional high-pass filtering RF amplifier (Minicircuits Model ZFL-1000+). The quarter-wave plate is aligned such that the differential photo current measures the dif- ference between right- and left-hand circularly polarized components. The output voltage U is proportional to the observed ellipticity, i.e., U ( t ) = g el S z ( t ) with electronic
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A Low-Noise Transimpedance Amplifier For Blm-Based Ion Channel Recording

A Low-Noise Transimpedance Amplifier For Blm-Based Ion Channel Recording

applications of these systems are to analyze EEG, ECG or neural signals for further medical diagnosis and scientific research [I]. And as revealed by biological study neural signals are typically IO-lOOOflV in amplitude and span a bandwidth of O.IHz- lO kHz. Due to the electrochemical effects on the surface of electrodes while being implanted in human body, a quite large DC offset will arise, which greatly challenges the design of precise front-end amplifiers featuring low noise, high CMRR, high input impedance and electrode DC offset suppression. Meanwhile, power consumption should be minimized and bandwidth could be set wide enough for neural signals. Four gm-stage amplifiers, auto correction feedback (ACFB) loop and capacitor- coupled topologies have been used in the proposed amplifier. The capacitor-coupled topology has several merits over others such as high input impedance, raiI-to-raiI sensing and high power 978-1-4799-3282-5/14/$3l.00 m014 IEEE efficiency[l]. Meanwhile, good matching between capacitors also improves the gain accuracy and CMRR. Chopping technique is widely used for high precision CMOS amplifiers to achieve low offset and low noise, which consequently brings about
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Coating-Free Mirrors
for Ultra-Sensitive Interferometry

Coating-Free Mirrors for Ultra-Sensitive Interferometry

At this point, thermal noise in the optics becomes an important consideration. This can be minimised with the choice of a constituent material of a high mechanical quality. Conventional optics employ coatings in order to reflect light, which causes a considerable reduction in the mechanical quality of the system with which the beam interacts. As is shown in Section 1.3, this is furthered by the fact that the thermal displacement noise, resulting from direct interaction with the optical coatings by the laser beam, is considerably higher for a small beam size. Hence, the design and implementation of a reflector with no coatings promises to allow the use of a small beam, with a decreased risk that thermal fluctuations override the quantum effects in this regime. This provides the means to lower the moment of inertia of the system, with a decrease in the power required for the observation of radiation pressure noise. An according rise in relative shot noise increases the likelihood of measurement of the standard quantum limit.
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Analysis of Electrochemical Impedance and Noise Data for AISI-310 Exposed to Lithium Bromide Solution

Analysis of Electrochemical Impedance and Noise Data for AISI-310 Exposed to Lithium Bromide Solution

The corrosion behavior of AISI-310 in aqueous lithium bromide solution (50.0 % w/w) at 25, 60 and 80ºC has been studied through polarization curves (PC), the electrochemical noise technique (EN) and the electrochemical-impedance spectroscopy (EIS). Physical characterization of the corroded samples indicated that AISI-310 exposed at 25ºC suffered a uniform corrosion process, whereas at 60 and 80ºC a mixed corrosion process was observed, which was in agreement with the localization indexes calculated from EN data. The corrosion activity was analyzed taking into account the noise pattern, which was alike for the three test temperatures, observing a low amplitude/high frequency noise with some medium intensity current transients, especially at the highest temperature. EIS results showed that the temperature is an important issue in the corrosion controlled reaction, since at 25ºC, a pure diffusion-controlled reaction was predominantly seen, at 60ºC an activation-controlled step was observed, whereas at the higher temperature both diffusion and charge transfer controlled steps were observed. The corrosion kinetics was calculated from the resistance noise obtained from EN data, and then the Stern-Geary equation and the Faraday’s Law were used. The corrosion kinetics showed that at 60ºC the corrosion rate was somewhat higher than that at 80ºC, which could also be seen in the electrochemical current noise, where the current density was higher at 60ºC. This behavior was supported due to the changes in the thermodynamic characteristics of the lithium bromide solution, since at 80ºC the aqueous solution at the experimental concentration tends to crystallize.
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ARB Life Improvement By Improvement in the Current Shot Peening Method

ARB Life Improvement By Improvement in the Current Shot Peening Method

Abstract— The ARB is widely used in automobiles and one of the major components of suspension system. It needs to have higher fatigue life. The ARB regarded as a safety component as its failure will lead to severe accidents and toppling of vehicle. The purpose of this paper is to predict the methods to improve the fatigue life of ARB by improvement in the shot penning process.

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Corrosion Performance of a Novel NiAl-Cu Intermetallic HVOF Protective Coating Part II: High Temperature Corrosion in Molten Salts

Corrosion Performance of a Novel NiAl-Cu Intermetallic HVOF Protective Coating Part II: High Temperature Corrosion in Molten Salts

On the other hand, electrochemical noise measurements (ENM) provide information of corrosion mechanisms, so this technique was eligible to monitor the NiAlCu coating hot corrosion process. The amplitude of the fluctuations observed in electrochemical noise records (ENR) can be correlated with the intensity of the corrosion process, while the fluctuation shape observed in these records can be associated with the type of corrosion process [7]. According to A. Aballe et al. electrochemical noise analysis often requires appropriate mathematical tools. Statistical methods have been proposed, based on spectral and other chaos theory. Bertocci et al. [8, 9] suggested that due to the inhomogeneity of the test electrodes during the ENMs it was possibly to cause a low frequency trend or DC trend coupled in the potential or current fluctuation which will produce 1/ƒ2 slopes in the PSD plots.
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Statistical Analysis of Multipath Fading Channels Using Generalizations of Shot Noise

Statistical Analysis of Multipath Fading Channels Using Generalizations of Shot Noise

The above analysis is important when designing specific receivers as follows. Assume that (1) represents the baseband received signal which is corrupted by additive white Gaussian noise. A well-known optimal receiver is the matched filter, which maximizes the output signal-to-noise ratio [1]. The implementation of the matched filter requires the knowledge of the power spectral density of (1), which is computed in the paper. Moreover, in many applications such as filter design and interference analysis, it is important to know the precise joint distribution of the processes ( { y l (t) } t ≥ 0 , { y(t) } t ≥ 0 ).
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Analysis of Image Noise Removal Methodologies for High Density Impulse Noise

Analysis of Image Noise Removal Methodologies for High Density Impulse Noise

Different filters uses different sorting algorithm like merge sort, quick sort, heap sort to sort the elements of window. Some techniques focused on noise detection, so there are different techniques to find out that the pixel is noisy or noiseless, so that only noisy pixel will be replaced by the median value and noiseless pixel will be unaffected. These techniques reduce the processing time and also improve the quality of image.

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