Shot Noise Research Papers - Academia.edu (original) (raw)

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The current and voltage fluctuations in a normal tunnel junction are calculated from microscopic theory. The power spectrum can deviate from the familiar Johnson-Nyquist form when the self-capacitance of the junction is small, at low... more

The current and voltage fluctuations in a normal tunnel junction are calculated from microscopic theory. The power spectrum can deviate from the familiar Johnson-Nyquist form when the self-capacitance of the junction is small, at low temperatures (C≲0.1 pF, T≲10 mK), ...

We have performed a comparison of laser (LsOPM) and lamp (LpOPM) pumped cesium vapor magnetometers. Although the LsOPM operated 50% above its shot-noise limit we found an intrinsic sensitivity of 15 fT/√Hz and 25 fT/√Hz for the LsOPM and... more

We have performed a comparison of laser (LsOPM) and lamp (LpOPM) pumped cesium vapor magnetometers. Although the LsOPM operated 50% above its shot-noise limit we found an intrinsic sensitivity of 15 fT/√Hz and 25 fT/√Hz for the LsOPM and the LpOPM, respectively. Two modes of operation, viz. the phase-stabilized and the self-oscillating modes, were investigated and found to yield a similar performance. We have compared the performance of the LsOPM and the LpOPM directly by simultaneous measurements of field fluctuations of a 2-μT magnetic field inside a multilayer magnetic shield and have used one of the magnetometers for an active field stabilization. In the stabilized mode we found a gradient instability of 25 fT within an integration time of 100 s, which represents an upper limit of the long-term stability of the magnetometers. Our research is motivated by the need for an improved control of magnetic fields and gradients in a planned neutron electric dipole experiment.

A concept is described for the detection and location of transient objects, in which a "pixel-binary" CMOS imager is used to give a very high effective frame rate for the imager. The sensitivity to incoming photons is enhanced... more

A concept is described for the detection and location of transient objects, in which a "pixel-binary" CMOS imager is used to give a very high effective frame rate for the imager. The sensitivity to incoming photons is enhanced by the use of an image intensifier in front of the imager. For faint signals and a high enough frame rate, a

Reportamos ruido Shot, ruido Browniano (1/f2) y ruido 1/f en nano-películas de Dió- xido de Vanadio (V O2). Se observa que el ruido Shot tiene dependencia lineal con la corriente y a bajas frecuencias es prácticamente independiente de la... more

Reportamos ruido Shot, ruido Browniano (1/f2) y ruido 1/f en nano-películas de Dió- xido de Vanadio (V O2). Se observa que el ruido Shot tiene dependencia lineal con la corriente y a bajas frecuencias es prácticamente independiente de la frecuencia. El es- pectro del ruido Shot nos arroja detalles físicos acerca de la mecánica de transporte de electrones en la nano-película de VO2 así como acerca de la transición de fase del vanadio que al darse a temperaturas cercanas a las del ambiente, va a tener importantes aplicaciones. Para detectar esto, se alejó la muestra de ruido externo mediante un fil- tro pasa bajas y se utilizó un analizador de espectros para que arroje frecuencia contra amplitud de la señal directa sin análisis de Fourier.

Objective- In this paper, we will demonstrate the two denoising techniques on medical images corrupted by poisson noise. These techniques are analyzed both qualitatively and quantitatively. Methods & analysis: The work is implemented in... more

Objective- In this paper, we will demonstrate the two denoising techniques on medical images corrupted by poisson
noise. These techniques are analyzed both qualitatively and quantitatively.
Methods & analysis: The work is implemented in Matlab software in image processing toolbox and for Quantitative
analysis mean square error(MSE) is used.
Findings: Image denoising by the PURE-LET yields better results.
Conclusion/improvement: PURE-LET techniques is better for denoising medical images corrupted with Poisson noise

We address the estimation of the loss parameter of a bosonic channel probed by Gaussian signals. We derive the ultimate quantum bound with precision and show that no improvement may be obtained by having access to the environmental... more

We address the estimation of the loss parameter of a bosonic channel probed by Gaussian signals. We derive the ultimate quantum bound with precision and show that no improvement may be obtained by having access to the environmental degrees of freedom. We find that, for small losses, the variance of the optimal estimator is proportional to the loss parameter itself, a result that represents a qualitative improvement over the shot-noise limit. An observable based on the symmetric logarithmic derivative is obtained, which attains the ultimate bound and may be implemented using Gaussian operations and photon counting.

ABSTRACT The study presents the analysis of detrended fluctuations (DFA) in inter spike intervals (ISI) of neuronal ensemble from cortex of awake behaving macaque monkeys. The original DFA method was applied to analyze fluctuation of... more

ABSTRACT The study presents the analysis of detrended fluctuations (DFA) in inter spike intervals (ISI) of neuronal ensemble from cortex of awake behaving macaque monkeys. The original DFA method was applied to analyze fluctuation of variances from fitted trends of different order. The spectrum of local scale exponent was calculated to investigate the presence of different scaling regions. It was observed that the single scaling exponent is insufficient to describe the firing pattern dynamics, the better fit is achieved using both short-term a1 and long-term α2 scaling coefficients. The validation procedure using phase randomized surrogates provided more reliable local scale exponents' estimates. Generalized DFA analysis revealed the presence of multifractality in ISI time series. Results indicate that multifractality is partly due to the broad probability distribution function and partly due to the presence of long-range correlations. Isodistributional surrogate data were used to test the significance of generalized Hurst exponent spectrum and origin of multifractal behavior. In conclusion, both DFA and its multifractal expansion reveal the presence of long-range correlation in ISI time series indicating the presence of memory in the neuronal firing pattern.

The fundamental sources of noise in a vacuum-tunneling probe used as an electromechanical transducer to monitor the location of a test mass are examined using a first-quantization formalism. We show that a tunneling transducer enforces... more

The fundamental sources of noise in a vacuum-tunneling probe used as an electromechanical transducer to monitor the location of a test mass are examined using a first-quantization formalism. We show that a tunneling transducer enforces the Heisenberg uncertainty principle for the position and momentum of a test mass monitored by the transducer through the presence of two sources of noise: the shot noise of the tunneling current and the momentum fluctuations transferred by the tunneling electrons to the test mass. We analyze a number of cases including symmetric and asymmetric rectangular potential barriers and a barrier in which there is a constant electric field. Practical configurations for reaching the quantum limit in measurements of the position of macroscopic bodies with such a class of transducers are studied.

Speckle structure of parametric down conversion light has recently received a large attention due to relevance in view of applications to quantum imaging The possibility of tailoring the speckle size by acting on the pump properties is an... more

Speckle structure of parametric down conversion light has recently received a large attention due to relevance in view of applications to quantum imaging The possibility of tailoring the speckle size by acting on the pump properties is an interesting tool for the applications to quantum imaging and in particular to the detection of weak object under shot-noise limit. Here we present a systematic detailed experimental study of the speckle structure produced in type II PDC with particular attention to its variation with pump beam properties.

The Fisher information FFF gives a limit to the ultimate precision achievable in a phase estimation protocol. It has been shown recently that the Fisher information for a linear two-mode interferometer cannot exceed the number of... more

The Fisher information FFF gives a limit to the ultimate precision achievable in a phase estimation protocol. It has been shown recently that the Fisher information for a linear two-mode interferometer cannot exceed the number of particles if the input state is separable. As a direct consequence, with such input states the shot-noise limit is the ultimate limit of precision. In this work, we go a step further by deducing bounds on FFF for several multiparticle entanglement classes. These bounds imply that genuine multiparticle entanglement is needed for reaching the highest sensitivities in quantum interferometry. We further compute similar bounds on the average Fisher information barF\bar FbarF for collective spin operators, where the average is performed over all possible spin directions. We show that these criteria detect different sets of states and illustrate their strengths by considering several examples, also using experimental data. In particular, the criterion based on barF\bar FbarF is able to detect certain bound entangled states.

We demonstrate a light-shot-noise-limited magnetometer based on the Faraday effect in a hot unpolarized ensemble of rubidium atoms. By using off-resonant, polarization-squeezed probe light, we improve the sensitivity of the magnetometer... more

We demonstrate a light-shot-noise-limited magnetometer based on the Faraday effect in a hot unpolarized ensemble of rubidium atoms. By using off-resonant, polarization-squeezed probe light, we improve the sensitivity of the magnetometer by 3.2 dB. The technique could improve the sensitivity of the most advanced magnetometers and quantum nondemolition measurements of atomic spin ensembles.

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