Shot Noise Research Articles

Unbiased centroiding of point targets close to the Cramer Rao limit.

Systematic errors affecting center-of-gravity (CoG) measurements may occur from coarse sampling of the point-spread-function (PSF) or from signal truncation at the boundaries of the region-of-interest (ROI). For small ROI and PSF widths, these effects are shown to become dominant, but this can be mitigated by introducing novel unbiased estimators that are largely free of systematic error and perform particularly well for low photon numbers. Analytical expressions for the estimator variances, comprising contributions from photon shot noise, random pixel noise, and residual systematic error, are derived and verified by Monte Carlo simulations. The accuracy and computational speed of the unbiased estimators are compared to those of other common estimators, including iteratively weighted CoG, thresholded CoG, iterative least squares fitting, and two-dimensional Gaussian regression. Each estimator is optimized with respect to ROI size and PSF radius and its error compared to the theoretical limit defined by the Cramer Rao lower bound (CRLB). The unbiased estimator with full systematic error correction operating on a small ROI [3×3] emerges as one of the most accurate estimators while requiring significantly less computing effort than alternative algorithms.

Simulation of shot noise effects in the EIC strong hadron cooling accelerator using real number of electrons

In the electron ion collider design, in order to achieve the peak luminosity 1034/cm 2/s with a reasonable lifetime, an efficient coherent electron cooling scheme was proposed to reduce the hadron beam emittance growth. Such a cooling scheme requires a good electron beam quality with a small energy spread. However, the shot noise in the electron beam through the accelerator might be amplified due to the microbunching instability and degrades the electron beam quality in the modulator section of the strong hadron cooling channel and correspondingly cooling rate. In this study, we report on self-consistent simulations of these effects using a real number of electrons to capture the details of shot noise and analysis of the shot noise growth through the accelerator.

Low-noise preamplifier for scanning tunneling microscope

The current preamplifier is one of the important components of the scanning tunneling microscope (STM), and its performance is crucial to the basic operations of the STM system, as well as for the development of demanding novel functionalities such as autonomous atomic fabrication. In this study, the factors that affect the performance of a current preamplifier, including its noise spectrum density and the bandwidth, are analyzed in depth, and a preamplifier is designed and fabricated specifically for the STM system. By using a carefully selected low-noise op amp chip, the optimized current preamplifier has a noise floor as low as 4 <inline-formula><tex-math id="M2">\begin{document}$ {\mathrm{f}}{\mathrm{A}}/\sqrt{{\mathrm{H}}{\mathrm{z}}} $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240560_M2.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240560_M2.png"/></alternatives></inline-formula> and a bandwidth of 2.3 kHz, at its most sensitive transimpedance gain of 1 GΩ. It has three transimpedance gains, 10 MΩ, 100 MΩ, and 1 GΩ, that can be switched through digital control signals. A two-switch configuration is adopted to minimize the noise floor while maintaining the optimal bandwidth. The current detectable by this three-level preamplifier ranges from pA to μA, satisfying the requirements of most STM operations. Using this preamplifier, the fundamental functions of the STM system are successfully demonstrated, including surface topographic characterization, scanning tunneling spectroscopy, and single atom/molecule manipulation. The measurement of shot noise in tunneling current is also explored, and a linear relationship between shot noise and tunneling current is obtained by carefully analyzing noise. It is illustrated that the Fano factor of the shot noise in a normal metallic tunneling junction is approximately equal to 1, revealing the expected Poisson process for electron tunneling in such a scenario. The results are valuable for the high-resolution characterization of correlation systems in the future.

Codebook Design for SCMA-Assisted Visible Light Communication with Shot Noise

Codebook Design for SCMA-Assisted Visible Light Communication with Shot Noise

Signal-Dependent Shot and Relative Intensity Noise in Channel Estimation of Laser Diode-based Indoor VLC Systems

Signal-Dependent Shot and Relative Intensity Noise in Channel Estimation of Laser Diode-based Indoor VLC Systems

Quantum-enhanced optical phase tracking via squeezed state

Quantum-enhanced optical phase tracking is a quantum optical technique for tracking and measuring optical phases with high accuracy. It has important applications in laser interferometry, spectral analysis, and optical measurements. In this study, we propose a quantum-enhanced optical phase tracking protocol based on squeezed state optical fields. By using a continuous solid-state laser source with a central wavelength of 1064 nm, combing second harmonic generation, optical parametric oscillator, and PDH (Pound-Drever-Hall) locking technology, we prepare an initial squeezed state with a squeezing level of (8.0±0.2) dB. Through signal modulation technique and demodulation technique, we control the phase of the squeezed state optical field, thereby realizing the quantum-enhanced tracking of optical phases within the range of 0－2π. Compared with classical protocols, this protocol can suppress the noise fluctuations of phase tracking to at least 6.27 dB below the shot noise limit, improving the phase tracking accuracy by more than 76.4%. Because of the high requirements for phase measurement accuracy in applications such as angle estimation, phased array radar, and phased array sonar, this protocol is expected to improve the phase estimation accuracy beyond the shot noise limit. It provides compressed light sources for relevant fields, laying a theoretical and experimental foundation for higher-precision spatial positioning and quantum ranging techniques. The probe is made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid residues. The sequence of amino acids in a protein is determined by a gene and encoded in the genetic code. This can happen either before the protein is used in the cell, or as part of control mechanism.

Learnability Enhancement for Low-Light Raw Image Denoising: A Data Perspective.

Low-light raw image denoising is an essential task in computational photography, to which the learning-based method has become the mainstream solution. The standard paradigm of the learning-based method is to learn the mapping between the paired real data, i.e., the low-light noisy image and its clean counterpart. However, the limited data volume, complicated noise model, and underdeveloped data quality have constituted the learnability bottleneck of the data mapping between paired real data, which limits the performance of the learning-based method. To break through the bottleneck, we introduce a learnability enhancement strategy for low-light raw image denoising by reforming paired real data according to noise modeling. Our learnability enhancement strategy integrates three efficient methods: shot noise augmentation (SNA), dark shading correction (DSC) and a developed image acquisition protocol. Specifically, SNA promotes the precision of data mapping by increasing the data volume of paired real data, DSC promotes the accuracy of data mapping by reducing the noise complexity, and the developed image acquisition protocol promotes the reliability of data mapping by improving the data quality of paired real data. Meanwhile, based on the developed image acquisition protocol, we build a new dataset for low-light raw image denoising. Experiments on public datasets and our dataset demonstrate the superiority of the learnability enhancement strategy.

The effective field theory of large-scale structure and multi-tracer II: redshift space and realistic tracers

We extend the multi-tracer (MT) formalism of the effective field theory of large-scale structure to redshift space, comparing the results of MT to a single-tracer analysis when extracting cosmological parameters from simulations. We used a sub-halo abundance matching method to obtain more realistic multi-tracer galaxy catalogs constructed from N-body simulations. Considering different values for the sample shot noise and volume, we show that the MT error bars on A s, ω cdm, and h in a full-shape analysis are approximately 50% smaller relative to ST. We find that cosmological and bias coefficients from MT are less degenerate, indicating that the MT parameter basis is more orthogonal. We conclude that using MT combined with perturbation theory is a robust and competitive way to accommodate the information present in the mildly non-linear scales.

Prediction of the ESD Failure Current Based on a New Method Using the Shot Noise Model

Prediction of the ESD Failure Current Based on a New Method Using the Shot Noise Model

Low-Light Phase Retrieval With Implicit Generative Priors.

Phase retrieval (PR) is fundamentally important in scientific imaging and is crucial for nanoscale techniques like coherent diffractive imaging (CDI). Low radiation dose imaging is essential for applications involving radiation-sensitive samples. However, most PR methods struggle in low-dose scenarios due to high shot noise. Recent advancements in optical data acquisition setups, such as in-situ CDI, have shown promise for low-dose imaging, but they rely on a time series of measurements, making them unsuitable for single-image applications. Similarly, data-driven phase retrieval techniques are not easily adaptable to data-scarce situations. Zero-shot deep learning methods based on pre-trained and implicit generative priors have been effective in various imaging tasks but have shown limited success in PR. In this work, we propose low-dose deep image prior (LoDIP), which combines in-situ CDI with the power of implicit generative priors to address single-image low-dose phase retrieval. Quantitative evaluations demonstrate LoDIP's superior performance in this task and its applicability to real experimental scenarios.

Analyzing the effect of shot noise in indirect Time-of-Flight cameras

Continuous wave indirect Time-of-Flight cameras obtain depth images by emitting a modulated continuous light wave and measuring the delay of the received signal. In this paper we generalize the estimation of the effect of the shot noise when obtaining the phase delay with an arbitrary number of points in the Discrete Fourier Transform, extending and generalizing the analysis done in previous works for the case of four points. For that particular case, we compare our analysis with the state of art. Moreover, we extend the error model using a second order approximation in the error propagation analysis, which provides more accurate estimations according to the Montecarlo simulation experiments. The analysis, based on both analytical and numerical methods, shows that the phase error is, in general, related to the exposure time and weakly to the number of points in the Discrete Fourier Transform. It also depends on the background illumination level, on the amplitude of the received signal, and, when using a three point DFT, on the distance to the objects.

Near thermal noise limit, 5W single frequency fiber laser base on the ring cavity configuration.

In this study, we present an ultralow noise single-frequency fiber laser operating at 1550 nm, utilizing a traveling-wave ring cavity configuration. The frequency noise of the laser approaches the thermal noise limit, achieving a white noise level of 0.025 Hz2/Hz, resulting in an instantaneous linewidth of 0.08 Hz. After amplification, the output power reaches 4.94 W while maintaining the same low white noise level as the laser oscillator. The integration linewidths of the laser oscillator and amplifier are 221 Hz and 665 Hz, respectively, with both exhibiting relative intensity noises that approach the quantum shot noise limit. To the best of our knowledge, this work shows the lowest frequency noise combined with relatively high power for this type of ring cavity fiber laser.

Super-resolution stimulated Raman scattering microscopy enhanced by quantum light and deconvolution

Stimulated Raman scattering (SRS) microscopy is a powerful tool for label-free chemical contrast bio-imaging. However, its spatial resolution is limited by diffraction; its noise level is also fundamentally limited by the shot noise due to the quantum nature of light. In this work, we apply the squeezed light technique associated with the deconvolution method to achieve quantum-enhanced super-resolution SRS microscopy. To generate squeezed pump light, we design a unique cascaded scheme by using two nonlinear crystals, in which the second-harmonic generation (SHG) from the first crystal is used to boost the SHG of the second crystal sequentially. Such a cascaded light squeezed scheme suppresses the shot noise down to 89.7% (1 dB), which can be readily applied to the existing conventional SRS microscopy. We combine the squeezed light-controlled SRS with the Richardson–Lucy deconvolution method to break the diffraction limit by improving the spatial resolution of ∼2.2-fold compared to conventional SRS imaging. We realize the quantum-enhanced super-resolution SRS imaging in a variety of samples (e.g., oleic acid, porcine muscle tissue), suggesting the potential of squeezed light SRS with deconvolution for label-free super-resolution chemical imaging in biological and biomedical systems.

Quantum Noise Source Based on Shot Noise of a Balanced Photodetector with a Tunable Integrated Optical Beam Splitter

Quantum Noise Source Based on Shot Noise of a Balanced Photodetector with a Tunable Integrated Optical Beam Splitter

High-power quantum-limited 35 MHz photodiode and classical laser noise suppression

To benefit high-power interferometry and the creation of low-noise light sources, we develop a simple lead-compensated photodetector enabling quantum-limited readout from 0.3 to 10 mW and 10 kΩ gain from 85 Hz to 35 MHz, with a noise equivalent power of 9 pW/Hz. Feeding the detector output back to an intensity modulator, we suppress the classical amplitude noise of a commercial 1550 nm fiber laser to the shot noise limit over a bandwidth of 700 Hz–200 kHz, observing no degradation to its (nominally ∼100 Hz) linewidth.

Research on particle noise based on second-order effect

The development of integrated circuits has gone through several stages, from the invention of transistors to the emergence of very large scale integrated circuits and system level integrated circuits. Now, the size of integrated circuits enters the nanometer level, and short-channel shot noise becomes an important issue. Short-channel shot noise increases due to factors such as device size reduction and scattering during channel formation. It has a serious impact on the performance, power consumption and reliability of integrated circuits. The formation mechanism of short channel shot noise can be explained from two aspects: one is due to the existence of thermal noise inside the channel, and the other is due to the noise caused by the shot. As the device size decreases, the channel thermal noise gradually changes into shot noise and becomes one of the main noise sources. Aiming at the noise generation mechanism, this paper proposes several methods to solve the short-channel shot noise. Through the research of short-channel shot noise and the exploration of solutions, the impact of shot noise on IC performance can be better understood and dealt with, and the development and innovation of IC technology can be promoted.

Colloidal InSb Quantum Dots for 1500nm SWIR Photodetector with Antioxidation of Surface.

III-V quantum dots (QDs) have emerged as significant alternatives to Cd- and Pb-based QDs, garnering notable attention over the past two decades. However, the understanding of III-V QDs, particularly in the short wave-infrared (SWIR) region, remains limited. InAs QDs are widely recognized as the most prominent SWIR QDs, but their absorption beyond 1400nm presents various challenges. Consequently, InSb QDs with relatively narrower bandgaps have been investigated; however, research on their device applications is lacking. In this study, InSb QDs are synthesized with absorption ranging from 1000 to 1700nm by introducing Cl- ions to enhance QD surface stability during synthesis. Additionally, it coated InAs and ZnSe shells onto the InSb QDs to validate photoluminescence in the SWIR region and improve photostability. Subsequently, these QDs are employed in the fabrication of photodetector devices, resulting in photodetection above 1500nm using Pb-free QDs. The photodetection device exhibited an external quantum efficiency (EQE) of 11.4% at 1370nm and 6.3% at 1520nm for InSb core QDs, and 4.6% at 1520nm for InSb/InAs core/shell QDs, marking the successful implementation of such a device. In detail, the 1520nm for InSb core device showed a dark current density(JD ) value of: 1.46 × 10-9 A/cm2 , responsivity(R): 0.078 A/W, and specific detectivity based on the shot noise(Dsh *): 3.6×1012 Jones at 0V.

A method of weak lensing reconstruction through cosmic magnification with multiband photometry information

ABSTRACT Weak gravitational lensing induces flux-dependent fluctuations in the observed galaxy number density distribution. This cosmic magnification (magnification bias) effect in principle enables lensing reconstruction alternative to cosmic shear and cosmic microwave background lensing. However, the intrinsic galaxy clustering, which otherwise overwhelms the signal, has hindered its application. Through a scaling relation found by principal component analysis of the galaxy clustering in multiband photometry space, we design a minimum variance linear estimator to suppress the intrinsic galaxy clustering and to reconstruct the lensing convergence map. In combination of the CosmoDC2 galaxy mock and the CosmicGrowth simulation, we test this proposal for an LSST (Large Synoptic Survey Telescope)-like galaxy survey with ugrizY photometry bands. (1) The scaling relation holds excellently at multipole ℓ < 103, and remains reasonably well to ℓ ∼ 3000. (2) The linear estimator efficiently suppresses the galaxy intrinsic clustering, by a factor of ∼102. (3) For galaxies in the photo-z range 0.8 < zκ < 1.2, the reconstructed convergence map is cosmic variance limited per ℓ mode at ℓ < 102, and shot noise limited at $\ell \gtrsim 200$. (4) Its cross-correlation with cosmic shear of galaxies can achieve $\mathrm{ S/N}\gtrsim 200$. When the source redshift of cosmic shear galaxies zγ < zκ, the systematic error is negligible at all investigated scales (ℓ < 3000). When zγ ≥ zκ, the systematic error caused by the residual intrinsic galaxy clustering becomes non-negligible. We discuss possible mitigation of the residual intrinsic galaxy clustering required for accurate measurement at ℓ > 103. This work further demonstrates the potential of lensing measurement through cosmic magnification to enhance the weak lensing cosmology.

Shot noise in a strange metal.

Strange-metal behavior has been observed in materials ranging from high-temperature superconductors to heavy fermion metals. In conventional metals, current is carried by quasiparticles; although it has been suggested that quasiparticles are absent in strange metals, direct experimental evidence is lacking. We measured shot noise to probe the granularity of the current-carrying excitations in nanowires of the heavy fermion strange metal YbRh2Si2. When compared with conventional metals, shot noise in these nanowires is strongly suppressed. This suppression cannot be attributed to either electron-phonon or electron-electron interactions in a Fermi liquid, which suggests that the current is not carried by well-defined quasiparticles in the strange-metal regime that we probed. Our work sets the stage for similar studies of other strange metals.

Enhancing measurement precision through noise analysis and fringe optimization in white light interferometry

White light interferometry is a highly precise non-contact measurement technology. However, in practical applications, certain noise sources such as thermal noise, shot noise, and redundant intensity noise, can introduce signal distortion. In this paper, we propose a mathematical formulation for the key metric, Quality Factor, which serves as an evaluation criterion for the quality of interference signals. The influence of different factors on the measurement is quantitatively analyzed using the signal-to-noise ratio, and various filtering methods are employed to address different types of noise. Finally, experimental results highlight the primary factors and optimization techniques that significantly impact the quality of interference signals, thereby verifing the effectiveness of the method on measurement results.