Current Noise Levels Research Articles

Demonstration of a photonic integrated circuit for quantitative phase imaging

Quantitative phase imaging (QPI) is an optical microscopy method that has been developed over nearly a century to rapidly visualize and analyze transparent or weakly scattering objects in view of biological, medical, or material science applications. The bulky nature of the most performant QPI techniques in terms of phase noise limits their large-scale deployment. In this context, the beam shaping properties of photonic chips, combined with their intrinsic compact size and low cost, could be beneficial. Here, we demonstrate the implementation of QPI with a photonic integrated circuit (PIC) used as an add-on to a standard wide-field microscope. Combining a 50 mm×50 mm footprint PIC as a secondary coherent illuminating light source with an imaging microscope objective of numerical aperture 0.45 and implementing a phase retrieval approach based on the Kramers–Kronig relations, we achieve a phase noise of 5.5 mrad and a diffraction limited spatial resolution of 400 nm. As a result, we retrieve quantitative phase images of Escherichia coli bacteria cells and monolayers of graphene patches from which we determine a graphene monolayer thickness of 0.45±0.15 nm. The current phase noise level is more than five times lower than that obtained with other state-of-the-art QPI techniques using coherent light sources and comparable to their counterparts based on incoherent light sources. The PIC-based QPI technique opens new avenues for low-phase noise, miniature, robust, and cost-effective quantitative phase microscopy.

Experimental study on phase noise of terahertz quantum cascade laser frequency comb and dual-comb sources

Frequency combs with equally spaced frequency lines show great potentials for applications in spectroscopy, imaging, communications, and so on. In the terahertz frequency region, the quantum cascade laser (QCL) is an ideal radiation source for frequency comb and dual-comb operation. The systematic evaluation of phase noise characteristics of terahertz QCL frequency comb and dual-comb sources is of great importance for high precision measurements. In this work, we present detailed measurements and analysis of the phase noise characteristics of terahertz QCL frequency comb and dual-comb sources emitting around 4.2 THz with repetition frequencies of ~6.2 GHz. The measurement results for the current noise of the direct current (DC) sources (that are used to electrically pump the terahertz QCLs) indicate that at 100 Hz, the current noise for DC-1 and DC-2 is 0.3895 and 0.0982 nA/Hz1/2, respectively. Such levels of current noise can be safely disregarded. The phase noise of radio frequency (RF) generators (that are employed for injection locking and phase locking), intermode beatnotes, and dual-comb signals with and without phase-locked loop (PLL) are all measured and compared. The experimental results show that in the free-running mode, the phase noise of the intermode beatnote signals is always lower than that of the dual-comb signals across all frequencies. Additionally, the phase noise induced by the RF generators is negligible. By employing the phase locking technique, the phase noise of the intermode beatnote and dual-comb signals in the low offset frequency band can be significantly suppressed. At an offset frequency of 100 Hz, the measured phase noise values of the dual-comb line without and with phase locking are 15.026 and −64.801 dBc/Hz, respectively.

Impact of Road Traffic Noise from the R3 Expressway in the Sections Oravský Podzámok – Dolný Kubín – Highway D1

Abstract The components of Slovakia’s integrated transport infrastructure should be designed, constructed, maintained, and decommissioned at a reasonable cost and quality, respecting the relevant requirements of users, residents in the surrounding area, and the principles of sustainable development throughout its entire life cycle. A comprehensive integrated transport infrastructure must ensure multimodal, interoperable, and safe transport with the lowest possible carbon footprint, focused on regional development and cohesion, with maximum economically feasible minimization of environmental noise induced by traffic. This article provides the basis for fulfilling this premise in environmental noise reduction along the section of the first-class road I/59 from the village of Oravský Podzámok to the village of Likavka, where the current noise levels exceed the permissible values set by legislation. The solution to this problem is expected to be the construction of the R3 expressway, which is being considered in two variants.

Exploring AES Encryption Implementation Through Quantum Computing Techniques

A coming great revolution in technology is quantum computing, which opens new attacks on most of the developed cryptographic algorithms, including AES. These emerging quantum capabilities risk weakening cryptographic techniques, which safeguard a vast amount of data across the globe. This research uses Grover's algorithm to explore the vulnerabilities of the Advanced Encryption Standard to quantum attacks. By implementing quantum cryptographic algorithms and Quantum Error Correction on simulators and quantum hardware, the study evaluates the effectiveness of these techniques in mitigating noise and improving the reliability of quantum computations. The study shows that while AES is theoretically at risk due to Grover’s algorithm, which demonstrates a theoretical reduction in AES key search complexity, current hardware limitations and noise levels encountered in today’s quantum computers reduce the immediate threat and limit practical exploitation. The research also examines NTRU encryption, a quantum-resistant alternative, highlighting its robustness in quantum environments. The findings emphasize the need for further development in QEC and quantum-resistant cryptography to secure digital communications against future quantum threats. Future work will focus on advancing QEC techniques and refining quantum algorithms, addressing both hardware and theoretical advancements, including the potential use of high-capacity processors like Jiuzhang 3.0. These improvements will ensure the scalability of quantum-resistant systems to practical key sizes and usage scenarios.

Multidimensional analysis of road traffic noise and probable public health hazards in Barisal city corporation, Bangladesh

Noise pollution is a major challenge in urban contexts all around the world. The study was designed to assess road traffic noise pollution with possible health effects on those living in the study region. The IDW spatial interpolation approach and an ArcGIS-based evaluation were used to map the recorded noise levels in the research region. The noise descriptors including Noise Climate (NC), Traffic Noise Index (TNI), Equivalent Noise Level (Leq), and Noise Pollution Level (NPL) were computed. The required information has been collected through a questionnaire survey and previously published documents. The study reveals that the current noise level is higher than the recommended national threshold at every location. According to the study, the Nathullabad region had the highest level of noise pollution (86.5 dBA), while the Kaunia Abasik area had the lowest level (67.8 dBA). Study findings also show that in the area context, the highest levels of noise pollution are found in commercial areas (82 dBA), followed by industrial areas (80.4 dBA),mixed areas (81.3 dBA), and residential areas (72.7 dBA). The lowest level is found in sensitive areas (72.5 dBA). Statistical analyses, including one-way ANOVA, Tukey HSD post-hoc and LSD post-hoc test results, showed that there was no statistically significant difference (p > 0.05) between the noise pollution levels (NPL) in the morning, noon, and evening shifts. The results showed that 32 % of respondents stated they felt disturbed while working, and 27% of respondents said it was somewhat sensitive for them. As the last step in minimizing noise pollution in the research area, 37 % of respondents reported enforcing the regulations, 31% suggested making hydraulic horns illegally, and 21 % suggested raising public awareness. This study may contribute to academic knowledge and assist decision-makers of government officials in formulating appropriate local strategies to deal with this grave environmental problem.

A Data-driven Approach for Mitigating Dark Current Noise and Bad Pixels in Complementary Metal Oxide Semiconductor Cameras for Space-based Telescopes

In recent years, there has been a gradual increase in the performance of complementary metal oxide semiconductor (CMOS) cameras. These cameras have gained popularity as a viable alternative to charge-coupled device cameras in a wide range of applications. One particular application is the CMOS camera installed in small space telescopes. However, the limited power and spatial resources available on satellites present challenges in maintaining ideal observation conditions, including temperature and radiation environment. Consequently, images captured by CMOS cameras are susceptible to issues such as dark current noise and defective pixels. In this paper, we introduce a data-driven framework for mitigating dark current noise and bad pixels for CMOS cameras. Our approach involves two key steps: pixel clustering and function fitting. During the pixel clustering step, we identify and group pixels exhibiting similar dark current noise properties. Subsequently, in the function fitting step, we formulate functions that capture the relationship between dark current and temperature, as dictated by the Arrhenius law. Our framework leverages ground-based test data to establish distinct temperature–dark current relations for pixels within different clusters. The cluster results could then be utilized to estimate the dark current noise level and detect bad pixels from real observational data. To assess the effectiveness of our approach, we have conducted tests using real observation data obtained from the Yangwang-1 satellite, equipped with a near-ultraviolet telescope and an optical telescope. The results show a considerable improvement in the detection efficiency of space-based telescopes.

The effect of layout placement on acoustic conditions in call centers: Evaluations within the scope of an example

This article aimed to provide auditory comfort conditions in call centers where the noise problem is very high and its use is increasing day by day. Since there are no partition walls in such places, noises from conversations, telephones and other office equipment, footsteps, air conditioning and lighting, office equipment (fax machines, printers, etc.), and noise from outside can reduce working efficiency and sometimes cause serious health problems. To assess this situation, the current noise levels situation in a call center were revealed with the help of observation, survey, measurement, and simulation. The number of personnel in the volume, different layout models, surface absorption, and obstacle heights were analyzed through the simulation program and appropriate call center models were obtained in terms of acoustic comfort. By taking the models as a reference, noise level maps have been prepared according to different frequency spectrums. When the noise maps are evaluated, while the call center noise level is 60 dBA in the current situation, it has decreased to 45–53 dBA noise levels as a result of the settlement proposal where the employees are facing in opposite directions in pairs. There has been a reduction in noise level of approximately 16%. As a result of the study, the measures to be taken to improve the auditory environment were determined within the scope of architectural and acoustic design, and results were obtained to guide the designers.

Fast Fabrication Nanopores on a PMMA Membrane by a Local High Electric Field Controlled Breakdown.

The sensitivity and accuracy of nanopore sensors are severely hindered by the high noise associated with solid-state nanopores. To mitigate this issue, the deposition of organic polymer materials onto silicon nitride (SiNx) membranes has been effective in obtaining low-noise measurements. Nonetheless, the fabrication of nanopores sub-10 nm on thin polymer membranes remains a significant challenge. This work proposes a method for fabricating nanopores on polymethyl methacrylate (PMMA) membrane by the local high electrical field controlled breakdown, exploring the impact of voltage and current on the breakdown of PMMA membranes and discussing the mechanism underlying the breakdown voltage and current during the formation of nanopores. By improving the electric field application method, transient high electric fields that are one-seven times higher than the breakdown electric field can be utilized to fabricate nanopores. A comparative analysis was performed on the current noise levels of nanopores in PMMA-SiNx composite membranes and SiNx nanopores with a 5 nm diameter. The results demonstrated that the fast fabrication of nanopores on PMMA-SiNx membranes exhibited reduced current noise compared to SiNx nanopores. This finding provides evidence supporting the feasibility of utilizing this technology for efficiently fabricating low-noise nanopores on polymer composite membranes.

Ultra-low noise front-end design for smart optical sensors with high sensitivity and wide dynamic range.

Ultra-low noise is a critical component in the design of high-precision sensor front-ends. We introduced differential phase-sensitive detection (d-PSD) to mitigate both multiplicative and additive noise in optical sensors, aiming for an enhanced performance and cost-effectiveness. The d-PSD combines a capacitive transimpedance amplifier (C-TIA), a delta-sigma analog-to-digital converter (ΔΣ-ADC), and a software-based lock-in amplifier (s-LIA). The first two components utilize the DDC112 (a dual current input 20-bit ADC) for a minimal analog channel length, thus reducing noise efficiently, while the latter employs a cost-effective 32-bit microcontroller unit (MCU), the HC32F460. This approach was successfully implemented as the front-end for a smart optical sensor. Testing indicated that the sensor achieved an equivalent current noise level of 0.6 nA/√Hz, primarily attributed to the light source driver rather than the sensor's front-end circuit. The sensor exhibited an exceptional performance, with a 3σ measurement precision of 5.4 × 10-4 over a 1-second integration time and a dynamic range of 100 dB, leveraging the proposed method and design. Furthermore, the front-end of the sensor boasts a compact size, low power consumption, and affordability, making it an ideal, versatile solution for ultra-high precision, smart optical sensors.

Cryogenic Resonant Amplifier for Electron-on-Helium Image Charge Readout

AbstractAn electron-on-helium qubit is a promising physical platform for quantum information technologies. Among all the “blueprints” for the qubit realization, a hybrid Rydberg-spin qubit seems to be a promising one toward quantum computing using electron spins. The main technological challenge on the way to such qubits is a detection of fA range image current induced by a Rydberg transition of a single electron. To address this problem, we aim to use a tank LC-circuit in conjunction with a high-impedance and low power dissipation cryogenic amplifier. Here, we report our progress toward realization of a resonant image current detector with a homemade cryogenic amplifier based on FHX13LG HEMT. We present a detailed characterization of the transistor at room and cryogenic temperatures, as well as details of the amplifier design and performance. At the power dissipation level of amplifier well below 100 μW, the measured voltage and current noise level are $$0.6~{\hbox {nV}}/\sqrt{\textrm{Hz}}$$ 0.6 nV / Hz and below 1.5 fA/$$\sqrt{\textrm{Hz}}$$ Hz , respectively. Based on the actual image current measurements of the Rydberg transition in a many-electron system on liquid helium, we estimate an SNR = 8 with a measurement bandwidth 1 Hz for the detection of a single-electron transition, providing the noise level at the output is solely determined by the noise of the amplifier.

A new particle filter algorithm filtering motion artifact noise for clean electrocardiogram signals in wearable health monitoring system.

With the evolution of wearable systems, more and more people tend to wear wearable devices for health monitoring during sports. However, a large amount of motion artifact noise is introduced at this time, which is difficult to filter out due to its stochasticity. The amplitude and characteristics of motion artifact noise vary with changes in motion intensity. In order to filter out the motion artifact noise, the paperproposes a new particle algorithm, which can detect the intensity of the motion artifact for adaptive filtering, especiallysuitable for wearable health monitoring systems. In this algorithm, variational mode decomposition was first introduced to analyze the noisy electrocardiogram (ECG) signal in order to find the clean components. Then, the Laguerre estimation technique was applied to obtain an accurate ECG polar model. Taking this model as the state equation, a particle filter algorithm was defined to filter out the motion artifact noise. In the particle filter algorithm, we defined a parameter γ whose values were obtained from the six-axis data of motion sensor MPU6050 in our wearable device. This parameter γ could reflect the current noise levels and adaptively update the particle weights. Finally, some exercise experiments proved that the parameter γ could map the motion artifacts in real time and also demonstrated the superiority of the algorithm in terms of signal-to-noise ratio improvement and error reduction compared to other algorithms. The new particle filter algorithm proposed in this paper combines the six-axis data (three-axis accelerometer and three-axis gyroscope) with the ECG signal to effectively eliminate a large amount of motion artifact noise, thus solving the problem of excess noise from wearable devices when people are exercising, allowing them to accurately obtain real-time ECG health information.

The impact of cross-covariances between the CMB and reconstructed lensing power

Weak gravitational lensing of the Cosmic Microwave Background (CMB) changes CMB statistics in a nontrivial way, allowing for reconstruction of the lensing potential and the use of these reconstructed maps in determining cosmological parameters that affect the formation of intervening large-scale structures. Although in principle there are correlations between the primary CMB and the reconstructed lensing potential due to the lensing procedure itself, in practice CMB analyses treat these as negligible when combining these band powers in likelihoods. In this paper we quantify explicitly the impact on parameter constraints due to these cross-covariances between the lensed CMB and reconstructed lensing power, and we compare to the effect of including all lensing-induced non-Gaussian covariances, which have previously shown to impact parameter constraints on the order of 10%. We perform our analysis for a range of experimental setups, scanning over instrumental noise levels of 0.5 to 10.0 μK-arcmin in temperature assuming fully polarized detectors, and using a fixed beam size of 1.4 arcmin. When the correlations between the lensed CMB and lensing power are neglected, we find that forecasted constraints shift by at most 3% of the error bar for a 6-parameter ΛCDM model, and for the noise levels considered in this paper. For some of the ΛCDM extensions considered here, however, these correlations have a nontrivial impact, in some cases more than 10% of the error bar, even for current experimental noise levels.

Characterizing current noise of commercial constant-current sources by using an optically pumped rubidium atomic magnetometer.

This paper introduces a method for characterizing the current noise of commercial constant-current sources (CCSs) using a free-induction-decay (FID) type optically pumped rubidium atomic magnetometer driven by a radio frequency magnetic field. We convert the sensitivity of the atomic magnetometer into the current noise of CCS by calibrating the coil constant. At the same time, the current noise characteristics of six typical commercial low-noise CCSs are compared. The current noise level of the Keysight model B2961A is the lowest among the six tested CCSs, which is 36.233 ± 0.022 nA/Hz1/2 at 1-25Hz and 133.905 ± 0.080 nA/Hz1/2 at 1-100Hz. The sensitivity of the atomic magnetometer is dependent on the current noise level of the CCS. The CCS with low noise is of great significance for high-sensitivity atomic magnetometers. This research provides an important reference for promoting the development of high precision CCS, metrology, and basic physics research.

Comparison of the input filter effect to PV panel by SEPIC MPPT converter

PV panel with front end converter for MPPT purpose is always employed for solar energy. The current that front end converter draws from PV panel are generally includes ripple regarding to operation mode of the converter and the type of converter. Such current ripple when it has higher magnitude is so harmful for the PV panel, it either shortened lifetime or results faults on PV panel. To overcome such drawbacks, input filter must be used with front end converter for PV panel connection. Although, in the literature, there are a few types of input filter, the effect of the filter and input current ripple and current noises are not compared for PV panel integration. The original contribution of the study is the analysis of input filter types for PV panel integration. As an input filter, LCL, LCL with damping, LC, C filters are used, and their effects are compared for PV panel. In addition, as a front-end converter SEPIC converter is chosen because of having lower or higher output voltage regarding to input voltage. Besides, using LCL based filters as input filters of SEPIC converter are another contribution of the paper. By means of the applications with up to 15 W SEPIC converter and simulations with DC source and PV panel, it is shown that LC filter ensures better results using DC source by applications regarding current ripple and noise level. However, C filter is better for PV panel by simulations than DC source, it is because PV panel exhibits current source character, and LC filter has lower current ripple. Also with PV source, LCL with damping filter transfers higher energy to the load than the others. Furthermore, LCL type filter reduces inductor by 35% and capacitor by 4.7 times in total. Moreover, LCL filter has higher efficiency with 88% than others in the applications and lower ripple for simulations with DC source.

Highly Sensitive and Selective DNA Sequencing Device Using Metal Adatom Adsorption on 2D Phosphorene.

Two-dimensional (2D) material revolutionarily extends the technique capability of traditional nanopore/nanogap-based DNA sequencing devices. However, challenges associated with DNA sequencing on nanopores still remained in improving the sensitivity and specificity. Herein, by first-principles calculation, we theoretically studied the potential of transition-metal elements (Cr, Fe, Co, Ni, and Au) anchored on monolayer black phosphorene (BP) to act as all-electronic DNA sequencing devices. The spin-polarized band structures appeared in Cr-, Fe-, Co-, and Au-doped BP. Remarkably, the adsorption energy of nucleobases can be significantly enhanced on BP with Co, Fe, and Cr doping, which contribute to the enlarged current signal and lower noise levels. Furthermore, the order of nucleobases in terms of their adsorption energies onto the Cr@BP is C > A > G > T, which exhibits more distinct adsorption energies than Fe@BP or Co@BP. Therefore, Cr-doped BP is more effective to avoid ambiguity in recognizing various bases. We thus envisaged a possibility of a highly sensitive and selective DNA sequencing device based on phosphorene.

Yttrium-Iron Garnet Magnetometer in MEG: Advance towards Multi-Channel Arrays.

Recently, a new kind of sensor applicable in magnetoencephalography (MEG) has been presented: a solid-state yttrium-iron garnet magnetometer (YIGM). The feasibility of yttrium-iron garnet magnetometers (YIGMs) was demonstrated in an alpha-rhythm registration experiment. In this paper, we propose the analysis of lead-field matrices for different possible multi-channel on-scalp sensor layouts using YIGMs with respect to information theory. Real noise levels of the new sensor were used to compute signal-to-noise ratio (SNR) and total information capacity (TiC), and compared with corresponding metrics that can be obtained with well-established MEG systems based on superconducting quantum interference devices (SQUIDs) and optically pumped magnetometers (OPMs). The results showed that due to YIGMs' proximity to the subject's scalp, they outperform SQUIDs and OPMs at their respective noise levels in terms of SNR and TiC. However, the current noise levels of YIGM sensors are unfortunately insufficient for constructing a multichannel YIG-MEG system. This simulation study provides insight into the direction for further development of YIGM sensors to create a multi-channel MEG system, namely, by decreasing the noise levels of sensors.

Ultrahigh-Sensitivity and Fast-Speed Solar-Blind Ultraviolet Photodetector Based on a Broken-Gap van der Waals Heterodiode.

Broad-bandgap semiconductor-based solar-blind ultraviolet (SBUV) photodetectors have attracted considerable research interest because of their broad applications in missile plume tracking, flame detectors, environmental monitoring, and optical communications due to their solar-blind nature and high sensitivity with low background radiation. Owing to its high light absorption coefficient, abundance, and wide tunable bandgap of 2-2.6 eV, tin disulfide (SnS2) has emerged as one of the most promising compounds for application in UV-visible optoelectronic devices. However, SnS2 UV detectors have some undesirable properties such as slow response speed, high current noise level, and low specific detectivity. This study reports a metal mirror-enhanced Ta0.01W0.99Se2/SnS2 (TWS) van der Waals heterodiode-based SBUV photodetector with an ultrahigh photoresponsivity (R) of ∼1.85 × 104 AW-1 and a fast speed with rising time (τr) of 3.3 μs and decay time (τd) of 3.4 μs. Notably, the TWS heterodiode device exhibits a significantly low noise equivalent power of ∼1.02 × 10-18 W Hz-1/2 and a high specific detectivity of ∼3.65 × 1014 cm Hz1/2 W-1. This study provides an alternative method for designing fast-speed SBUV photodetectors with enormous potential in applications.

Chip platforms with synthetic lipid bilayers for electrophysiological analyses of pore proteins and extracellular vesicles

In this paper, we present microfluidic chip platforms to enable electrophysiological measurements of nanometer-sized extracellular vesicles. The basis of the chip platform is the realization of a synthetic free-standing lipid bilayer spanned within a microfabricated aperture. To allow ion channel current measurements, the background current noise level should be reduced to a minimum. This can be realized by coating microfabricated apertures from silicon, silicon oxide, or silicon nitride with PTFE or Parylene. Three promising chip platform designs are presented. Electrophysiological measurements conducted with these microfluidic systems show gating events of membrane proteins fused into synthetic lipid bilayers.

Variational Determination of Multiqubit Geometrical Entanglement in Noisy Intermediate-Scale Quantum Computers

Current noise levels in physical realizations of qubits and quantum operations limit the applicability of conventional methods to characterize entanglement. In this adverse scenario, we follow a quantum variational approach to estimate the geometric measure of entanglement of multiqubit pure states. The algorithm requires only single-qubit gates and measurements, so it is well suited for noisy intermediate-scale quantum devices. This is demonstrated by successfully implementing the method on IBM Quantum devices for Greenberger-Horne-Zeilinger states of three, four, and five qubits. Numerical simulations with random states show the robustness and accuracy of the method. The scalability of the protocol is numerically demonstrated via matrix-product-state techniques up to $25$ qubits.

ANALYSIS OF MEASURED ROAD AND RAILWAY TRAFFIC NOISE LEVELS WITH NOISE MAPPING AND PROPOSED ACTIVITIES

Due to the fast process of urbanization and the increase in the development of transport infrastructure, there is an increase in noise levels caused by road and railway traffic in urban areas, which represents one of the most important today's problems. The goal of this paper is to find out the current noise levels of road and railway traffic. Measuring road traffic noise levels in the area of the city of Zenica and the railway traffic noise in the vicinity of the Railway Station in Kakanj has been done. In the end, the analysis of the obtained results and comparisons with the values regulated by the law as allowed values were performed. Noise level maps were also plotted as one of the contributions to solving the problem of environmental noise.