Noise Limit Research Articles

Deterministic sub-Heisenberg limit phase sensitivity with the squeezed coherent state via balanced homodyne detection

Abstract We focus on the phase sensitivities of three schemes with the input of the squeezed coherent state based on the Mach-Zehnder interferometer (MZI).
 By the usage of the balanced homodyne detection, the phase sensitivities of the schemes can beat the shot noise limit and reach the sub-Heisenberg limit. 
Both the phase sensitivity with the balanced homodyne detection and the quantum Cramer-Rao bound can be better by altering the combination of the two-mode squeezed parameter and the photon number of the coherent state. 
These schemes also have good robustness against the internal loss of the MZI and the loss of the photon detector. 
In the low squeezing parameter region, the phase sensitivity with the two-mode squeezed coherent state is the optimal among the three schemes. This work will play important roles in the field of quantum precision measurement.

Some big issues with small noise limits in Markov decision processes

Using the framework of Markov decision processes (equivalently, controlled Markov chains) as a test case, we point out some non-robustness issues that arise in small noise limits in stochastic control. This is used to motivate a novel formulation of multi-chain Markov decision processes.

Sustainable Seismic Practices in Offshore Exploration: A Conceptual Model for Minimizing Environmental Impact While Enhancing Resource Recovery

Offshore exploration for hydrocarbon resources often entails significant environmental challenges, including potential disruptions to marine ecosystems and water quality. This paper presents a conceptual model for sustainable seismic practices in offshore exploration, aiming to minimize environmental impact while enhancing resource recovery. The model integrates advanced seismic acquisition technologies with environmentally-conscious strategies, focusing on reducing operational risks, noise pollution, and seabed disturbances during data collection. Key components of the proposed model include the use of low-impact seismic sources, such as environmentally friendly air guns and vibroseis systems, designed to reduce underwater noise pollution and limit harm to marine life. Additionally, the model incorporates advanced real-time data processing techniques, which enable adaptive survey strategies that optimize data collection efficiency while minimizing the duration of operations in sensitive marine environments. The model emphasizes the importance of implementing noise mitigation technologies, including sound-absorbing materials and noise-canceling arrays, to reduce the adverse effects of seismic activities on marine fauna, particularly marine mammals and fish species. The conceptual framework also outlines the integration of renewable energy sources, such as solar and wind power, to support seismic operations, reducing reliance on fossil fuels and further decreasing the carbon footprint of offshore exploration. Furthermore, the model advocates for a comprehensive environmental monitoring system, which uses satellite imagery and underwater sensors to assess the impact of seismic operations on surrounding ecosystems in real time. This enables timely interventions to prevent or mitigate potential damage to the marine environment. A case study illustrates the application of this model in a deepwater offshore basin, demonstrating the potential for sustainable seismic practices to balance resource recovery with environmental preservation. The model's implementation results in a 20% reduction in operational costs and a significant decrease in the environmental footprint, showcasing its effectiveness in achieving sustainable offshore exploration practices.

Modulation-free laser frequency locking using Fano resonance in a crystalline whispering-gallery-mode cavity

A low-thermal-noise, small-sized, monolithic crystalline whispering-gallery-mode cavity can achieve a compact laser frequency locking system. In this study, we propose generating a Fano resonance spectrum within the crystalline cavity to achieve frequency locking without the need for traditional modulation techniques, aiming to further simplify the locking system. By coupling a prism with the crystalline cavity, we generate a Fano transmission spectrum to serve as the error signal for laser frequency locking. Experimental results show that our method achieves a level of noise suppression comparable to the classical Pound-Drever-Hall technique, reducing laser frequency noise to near the thermal noise limit of the crystalline cavity. It enables us to suppress the laser frequency noise to below 1 Hz2/Hz in the offset frequency range of 103–105 Hz and achieve a minimum noise of 0.2 Hz2/Hz. We also analyzed various unique optical noises in the Fano locking technique and found that the primary factor limiting laser frequency noise in this work is still the inherent thermal noise of the crystalline cavity. Our results indicate that the proposed Fano locking technique has significant potential to simplify laser locking systems, enhance stability, and reduce overall power consumption and cost.

A Comparative Implementation of Iris Flower Classification Across Platform

This paper presents a comparative analysis of the Iris Flower Classification problem implemented across three distinct computational platforms: classical computing using Jupyter Notebook, cloud computing via Google Colab, and quantum computing leveraging IBM Qiskit. The study evaluates the platforms based on execution efficiency, classification accuracy, and scalability. While classical and cloud-based implementations yielded similar performance metrics, the quantum approach demonstrated unique computational characteristics and challenges, such as noise and resource limitations. This research highlights the growing potential of quantum computing for machine learning applications and provides a foundation for future advancements in integrating quantum techniques with traditional methodologies. Key Words: Iris Flower Classification, Machine Learning, Classical Computing, Cloud Computing, Quantum Computing, Qiskit, Google Colab, Quantum Machine Learning, Comparative Analysis

METHODOLOGY FOR UNCERTAINTY ESTIMATION OF SHORT-TERM TOTAL ENVIRONMENTAL NOISE MEASUREMENTS

The third edition of the ISO 1996 series describes the methods for measuring and assessing environmental noise from different noise source types (road, rail and air traffic, and industrial plants). Additionally, these standards provide guidelines for assessing the uncertainty of short-term and long-term environmental noise measurements, considering the impact of various sources of uncertainty. The procedure described for assessing measurement uncertainty refers to the specific noise of individual noise sources (road, rail and air traffic, and industrial plants) and cannot be directly applied when considering the total noise contributed by multiple, diverse, near and far sources in each situation at a specific time, along with the corresponding measurement uncertainty. The limit values of the noise indicators specified by the Serbian regulations refer to the total noise, so it is necessary to determine the noise indicators for the total noise to assess environmental noise in each situation and at a given time. Although Serbian legislation does not require the use of measurement uncertainty in environmental noise assessments, the uncertainty must be determined and reported in the measurement report according to the requirements of the third edition of the ISO 1996 series. This paper aims to provide a detailed procedure for assessing the uncertainty of total environmental noise measurements for individual noise in the context of Serbian legislation and the third edition of the ISO 1996 series. The presented procedure can also be applied in other countries where noise limit values refer to total noise.

Picometer sensitive prototype of the optical truss interferometer for LISA

Abstract The optical truss interferometer (OTI) is a contingent subsystem proposed for the LISA telescopes to aid in the verification of a 1 pm Hz optical path length stability. Each telescope would be equipped with three pairs of compact fiber-coupled units, each forming an optical cavity with a baseline proportional to the telescope length at different points around the aperture. Employing a Pound–Drever–Hall approach to maintain a modulated laser field on resonance with each cavity, the dimensional stability of the telescope can be measured and verified. We have designed and developed prototype OTI units to demonstrate the capability of measuring stable structures, such as the LISA telescope, with a 1 pm Hz sensitivity using a set of freely mountable fiber-injected cavities. Aside from its initial motivation for the telescope, the OTI can also be readily integrated with other systems to aid in ground testing experiments. In this paper, we outline our experimental setup, measurement results, and analyses of the noise limitations.

A regional road network traffic noise limit prediction method based on design elements.

Since traffic flow has not been generated, a traffic noise prediction model based on actual traffic state data cannot be directly applied to the planned road network. Therefore, a regional traffic noise prediction method is proposed to find the upper limit of network noise emission based on design elements. The model is developed with noise predictions of the basic road section, interrupted/continuous intersections, and regional network. Meanwhile, ranges of traffic flow speed and volume are inferred by design elements and constraints between road units are obeyed. A four-scenes experiment to verify the method's accuracy is organized and the average noise difference between the upper limit calculated value and maximum measurement value is 1.53 dBA. All noise differences are positive as the measured noise values may not reach the upper limit of network emission in the experimental state. The method is applied to a network under design elements, and the results show that the model is suitable for the predicting upper limits of noise under design constraints; under the same design elements, noise emission at interrupted intersections is higher than that at continuous intersections. The method can provide a theoretical and data basis for planning network noise protection.

Influence of transmitting and receiving telescope parameters on measurement resolution of fiber laser doppler vibrometer

<sec>In a laser Doppler vibrometer (LDV), the laser Doppler effect is used to real-time acquire target displacement, velocity, and acceleration. Fiber optic laser vibrometers have received widespread attention in recent years due to their strong environmental adaptability and high integration advantages. With the expansion of detection target distance, higher requirements have been put forward for the measurement resolution of laser vibrometers. The LDV system typically employs a transceiver integrated telescope structure for laser emission and target return light reception. The aperture and focal length of the transceiver telescope determine its basic structure, directly affecting the emission and reception efficiency of laser energy. Additionally, the speckle effect generated by the scattering of rough targets affects the coupling of light energy entering the fiber optic for interference, thereby influencing the LDV measurement resolution.</sec><sec>Based on relevant theories such as Gaussian beam waist transmission, rough target generation, Fresnel diffraction integration, and fiber optic coupling, a transceiver integrated fiber optic laser vibrometer optical field transmission model is established. Numerical simulation and analysis of the emission transmission process of ideal Gaussian laser and the coupling process of surface target echo reception are conducted. Based on the assumption of laser vibrometer speckle noise limitation, an evaluation scheme for the instrument’s noise baseline under rough target return light conditions is proposed. Numerical simulation experiments are conducted for a typical fiber LDV application scenario with an alignment distance of 1 km, a single-mode fiber mode field radius of 5 μm, and a laser wavelength of 1550 nm. The results indicate that the focal length and aperture of the transceiver telescope determine the distribution of system energy utilization and further affect the instrument’s noise baseline. Simulation results show that when the F-number of the transceiver lens reaches 3.3, LDV achieves the highest system energy utilization at this focal length, verifying the correctness of the simulation model. The simulation results can serve as a basis for the design of transceiver lenses for fiber optic laser vibrometers, laser anemometers, and other devices.</sec>

ARRTOC: Adversarially Robust Real-Time Optimization and Control

Real-Time Optimization (RTO) plays a crucial role in process operation by determining optimal set-points for lower-level controllers. However, tracking these set-points can be challenging at the control layer due to disturbances, measurement noise, and actuator limitations, leading to a mismatch between expected and achieved RTO benefits. To address this, we present the Adversarially Robust Real-Time Optimization and Control (ARRTOC) algorithm. ARRTOC addresses this issue by finding set-points which are both optimal and inherently robust to implementation errors at the control layers. ARRTOC draws inspiration from adversarial machine learning, offering a novel constrained Adversarially Robust Optimization (ARO) solution applied to the RTO layer. We present several case studies to validate our approach, including a bioreactor, a multi-loop evaporator process, and scenarios involving plant-model mismatch. These studies demonstrate that ARRTOC can improve realized RTO benefits by as much as 50% compared to traditional RTO formulations that do not account for control layer performance.

A spin-refrigerated cavity quantum electrodynamic sensor

Quantum sensors based on solid-state defects, in particular nitrogen-vacancy (NV) centers in diamond, enable precise measurement of magnetic fields, temperature, rotation, and electric fields. Cavity quantum electrodynamic (cQED) readout, in which an NV ensemble is hybridized with a microwave mode, can overcome limitations in optical spin detection and has resulted in leading magnetic sensitivities at the pT-level. This approach, however, remains far from the intrinsic spin-projection noise limit due to thermal Johnson-Nyquist noise and spin saturation effects. Here we tackle these challenges by combining recently demonstrated spin refrigeration techniques with comprehensive nonlinear modeling of the cQED sensor operation. We demonstrate that the optically-polarized NV ensemble simultaneously provides magnetic sensitivity and acts as a heat sink for the deleterious thermal microwave noise background, even when actively probed by a microwave field. Optimizing the NV-cQED system, we demonstrate a broadband sensitivity of 576 ± 6 fT/Hz\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sqrt{{{{\\rm{Hz}}}}}$$\\end{document} around 15 kHz in ambient conditions. We then discuss the implications of this approach for the design of future magnetometers, including near-projection-limited devices approaching 3 fT/Hz\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sqrt{{{{\\rm{Hz}}}}}$$\\end{document} sensitivity enabled by spin refrigeration.

An optomechanical MEMS geophone with a 2.5 ng/Hz1/2 noise floor for oil/gas exploration

High-precision geophones play crucial roles in terrestrial applications such as oil and gas exploration as well as seismic monitoring. The development of optomechanical precision measurements provides a new design method for geophones, offering higher sensitivity and smaller dimensions compared to traditional geophones. In this work, we introduce an optomechanical microelectromechanical system (MEMS) geophone based on a plano-concave Fabry‒Perot (F–P) microcavity, which has a high sensitivity of 146 V/g. The F‒P microcavity consists of a movable mirror on the sensing element and a fixed hemispherical micromirror fabricated from silicon-on-insulator (SOI) and monocrystalline silicon wafers, respectively. The experimental results show that the geophone has a low noise floor of 2.5 ng/Hz1/2 (with a displacement noise floor of 6.2 fm/Hz1/2) within the frequency range of 100~200 Hz, a broad bandwidth of 500 Hz (–3 dB), and a measurement range of ±4 mg. To mitigate common-mode noise originating from the laser source and environmental factors such as temperature and air fluctuations, a balanced detection method is employed. This method substantially reduces the noise floor, nearly reaching the thermal noise limit (2.5 ng/Hz1/2). Furthermore, a compactly packaged optomechanical MEMS geophone with a diameter of 40 mm is demonstrated. The high performance and robust features hold great potential for applications in oil and gas exploration.

Continuous Quasi-Attractors dissolve with too much - or too little - variability.

Recent research involving bats flying in long tunnels has confirmed that hippocampal place cells can be active at multiple locations, with considerable variability in place field size and peak rate. With self-organizing recurrent networks, variability implies inhomogeneity in the synaptic weights, impeding the establishment of a continuous manifold of fixed points. Are continuous attractor neural networks still valid models for understanding spatial memory in the hippocampus, given such variability? Here, we ask what are the noise limits, in terms of an experimentally inspired parametrization of the irregularity of a single map, beyond which the notion of continuous attractor is no longer relevant. Through numerical simulations we show that (i) a continuous attractor can be approximated even when neural dynamics ultimately converge onto very few fixed points, since a quasi-attractive continuous manifold supports dynamically localized activity; (ii) excess irregularity in field size however disrupts the continuity of the manifold, while too little irregularity, with multiple fields, surprisingly prevents localized activity; and (iii) the boundaries in parameter space among these three regimes, extracted from simulations, are well matched by analytical estimates. These results lead to predict that there will be a maximum size of a 1D environment which can be retained in memory, and that the replay of spatial activity during sleep or quiet wakefulness will be for short segments of the environment.

Inertial active Ornstein–Uhlenbeck particle in a non-linear velocity dependent friction

We explore the self-propulsion of an active Ornstein–Uhlenbeck particle with a non-linear velocity dependent friction. Using analytical approach and numerical simulation, we have exactly investigated the dynamical behaviour of the particle in terms of particle trajectory, position and velocity distribution functions in both underdamped as well as overdamped regimes of the dynamics. Analysing the distribution functions, we observe that for a confined harmonic particle, with an increase in duration of self-propulsion, the inertial particle prefers to accumulate near the boundary of the confinement rather than the mean position, reflecting an activity induced bistability in the presence of nonlinear friction. On the other hand, in the overdamped or highly viscous regime, where the inertial influence is negligible, the sharp peak structure in the distribution across the mean position of the well reveals as usual trapping of the particle with increase in the persistent duration of activity. Moreover, for a free particle, using perturbation method, we have analytically computed the velocity distribution function in the vanishing limit of noise. The distribution interestingly shows the similar attributes as in case of a harmonic well, thus providing an additional effective confining mechanism that can be explained as a decreasing function of effective temperature. In this limit, the analytically computed distribution agrees well with the simulation results.

Three-dimensional turning force sensor based on a decagonal ring structure: crosstalk mitigation design and performance optimization

Abstract Real-time data acquisition using high-precision three-dimensional turning force sensors is crucial for intelligent manufacturing. However, existing sensors face challenges such as low integration levels and poor crosstalk resistance, rendering them inadequate for high-precision measurements. Theoretical analysis has demonstrated that a fully centered decagonal ring structure can effectively mitigate the effects of eccentric loading. This study focuses on designing a fully centered turning force sensor with minimal crosstalk. To achieve a balance between sensitivity and stiffness, multi-objective optimization was conducted using GWO-BP and TOP algorithms, resulting in a twofold increase in the sensitivity of the decagonal ring. The sensor design incorporates metallic strain gauges, instrumentation amplifiers, and peripheral circuits into the ring arms of the decagonal structure. Experimental results show that the sensor’s amplified sensitivities in the Fc, Ff, and Fp directions are 11.78 mV N−1, 10.31 mV N−1, and 1.78 mV N−1, respectively. The first three natural frequencies in an unconstrained state are 2518.5 Hz, 2537.5 Hz, and 4256.4 Hz. The sensor’s Fc-Fy crosstalk ranges from 0.18% to 0.88%, with noise limits for the Fc, Ff, and Fp directions of 0.035 N, 0.03 N, and 0.23 N, respectively. Cutting experiments have demonstrated that under varying spindle speeds and cutting depths, the sensor effectively detects surges in cutting force caused by rapid tool retraction, as well as other common faults.

Perancangan Prototype Monitoring dan Akuisi Data Pengujian Noise Trafo Berbasis ESP32

The noise level on the transformer is very important to be considered, because it can cause problems if it does not meet the standards. Excessive noise can violate regulations set by the Ministry of Environment regarding noise limit thresholds, In addition, excessive noise also indicates an indication of a bad transformer construction and will result in the performance of the transformer itself. PT Trafoindo Prima Perkasa, as one of the largest and first transformer manufacturers in Indonesia, tests every transformer produced, including its noise level, The testing is conducted in the Quality Check division. However, testing that is still done manually often causes queue buildup in the production line, along with the increasing demand, especially from PLN, a faster testing process is needed but still meets the set standards. Therefore, a faster, safer, and more efficient testing method is needed to support a continuous production. Based on this requirement, the author designs a prototype monitoring system and data acquisition of ESP32-based transformer noise testing to help speed up and simplify the testing process, so that the finished product can be sent immediately without reducing the quality and standards that have been set.

A Novel Bladeless-Spinal Wind Turbine Design for Efficient Energy Generation in Low wind Speeds

Wind energy is a widely used and renewable source for electricity generation. However, traditional wind turbines face challenges such as large footprints, noise, high costs, and efficiency limitations. To address these issues, bladeless wind turbines (BWTs) have gained popularity, and extensive research is being carried out to develop efficient designs. In this work, we propose a novel BWT design, inspired by the spine structure found in human bodies. The BWT architecture is modular, autonomous, and robust, making it suitable for small, portable, and small-scale applications. Our BWT design was inspired by the spine structure found in the human body and other vertebrates. The BSWT architecture is modular, autonomous, and robust. Detailed 3D models were created using Fusion 360 and SolidWorks software to refine and iterate the design. Our BWT features a complete electrical system with an energy harvesting base, a rectifier, converter, and a storage battery. The stored energy is then converted to AC and connected to the load. Our design utilizes oscillating rods divided into sections, enabling energy generation even at low wind speeds. The casing protects the rods from shear stresses and corrosion. While practical applicates involve a spine design with multiple sections, our experiments primarily focus on a single turbine.

Methods for addressing variable turbine operations during wind farm noise compliance monitoring

Post-construction wind farm noise measurements at dwelling locations are commonly required in Australia to verify compliance with noise limits. These are often required as soon as the wind farm begins operating. However, commissioning issues and electricity network restrictions are a common occurrence during initial stages of operation. As such, curtailed modes of operation and shutdowns are a regular occurrence, and large sections of a wind farm may only be operating intermittently. This presents challenges to obtaining noise measurement data that is representative of normal operation of the wind farm, and may ultimately limit the conclusions that are able to be reached from measurements during the early stages of operation. To address these challenges, it is necessary to identify and account for any periods when operational noise levels may be lower as a result of turbines being curtailed or shut down. Several methods have been developed for this purpose, and range from simple procedures that remove any data affected by curtailment or shutdown, through to more complex assessments of the magnitude and implications of the uncertainty introduced by variable wind turbine operations. These methods are presented and assessed in this paper with case studies of their application to operational projects.

Study of the acoustic features and exposures of some typical construction noise sources in India

Occupational noise research and occupational noise standards to date are limited to continuous, non-fluctuating broadband noise and uniform exposure. However, in many occupational environments, such as the construction sites, the workers may be exposed to continuous or intermittent noise of varied spectral and temporal patterns, and their exposure may not be continuous or uniform. These differences in sound signals and sound exposures may have different effect on humans. This paper studies the sound signals of various sources in construction sites of the institute campus through in-situ measurements. The key acoustic features and the spectral content of the sound signals are analyzed. The findings show that construction workers in India are exposed to construction noise with widely varying spectral content. A modified permissible upper limit of construction noise is developed for the presented case study and it is found that five out of eight studied construction sources violate the permissible limit and pose a noise hazard to the construction workers. The study suggests the need for updating occupational noise guidelines based on the noise types and exposure types; and imposing stricter measures for protecting the workers against the construction noise.

Annoyance evaluation of impact sounds on lightweight, concrete and cross-laminated timber floors - A comparative study

For people living in multi-unit residential buildings, neighbor noise and especially impact noise from neighbors, such as dropping objects or footsteps, can affect the quality of living of those who hear the noise. In order to support the inclusion of limits for impact noise in a future edition of the National Building Code of Canada, a project at the National Research Council of Canada has focused on the perceived annoyance from different types of impact sounds for various timber floor-ceiling assemblies. The results from listening experiments showed poor correlation between subjective ratings and objective single number metrics for impact noise due to persons walking without shoes. To extend this evaluation to a wider variety of floor-ceiling assembly types and to validate previous results, another listening experiment was conducted at the National Research Council. Annoyance ratings for ball drops, hammer impacts and footsteps on different lightweight, concrete and cross-laminated timber floor-ceiling assemblies were compared.