Thermal Noise Research Articles

Aviation noise in the United States: The current state of FAA research on community response

While today's civilian aircraft fleet is quieter than at any time in the history of jet-powered flight, the Federal Aviation Administration (FAA) continues to receive complaints about aircraft noise affecting communities across the United States. Additionally, the FAA's Neighborhood Environmental Survey (NES) has shown that community response to aviation noise in the United States has changed and the dose-response relationship between noise and annoyance such as the one represented by the Shultz Curve is no longer representative of communities' lived experiences. This paper will examine the current aviation noise environment in the United States and how the nature of aviation noise and the characteristics of communities that raise significant noise concerns in the United States have changed since the start of widespread use of commercial jet-powered aircraft in the 1960s. This paper will also explore the changing nature of community response to aviation noise based on the FAA's latest research findings on aviation noise and annoyance as detailed in follow-on analyses to the NES.

PARTNER project 1, low-frequency noise, and FAA's noise policy review

To improve upon current FAA noise policy, it seems reasonable to consider supplemental metrics. One of these is to include the annoyance impacts of low-frequency noise (LFN). It is established that LFN can cause rattle in homes near airports, causing annoyance. Current DNL 65 does not address LFN. In fact, most acoustical measurements do not include low frequencies due to the limitations of inexpensive measurement equipment. Hence, the FAA is genuinely missing these impacts from a physics point of view. The FAA has already paid for a very high quality LFN study through Project 1 in the PARTNER Center of Excellence (predecessor of the current ASCENT center). That project completed in 2007. The present author was not a participant in PARTNER Project 1, but he closely observed the amazing work done by the investigators from The Pennsylvania State University, Purdue University, and the University of Central Florida. If sufficient LFN data is regularly obtained at larger airports with improved noise monitoring equipment, then FAA could include supplemental metrics, such as the number of low-frequency noise events in a given period. [Work supported by the Penn State College of Engineering and its United Technologies Corporation Professorship.]

Realizing a 21st Century Noise Policy

Aviation noise impacts affect the health and quality of life of communities nationwide. The FAA's noise policy, last updated in the 1970s, uses a single decision-making metric (DNL), to determine the significance of noise impacts caused by aircraft operations. The Neighborhood Environmental Survey (NES), released in 2021, shows that many more people are impacted by aircraft noise and at levels far below 65 dB DNL than previously thought. The current noise policy does not reflect the 21st century airspace environment, including the consequences of NextGen and the tremendous growth in air traffic. An important improvement to realize an up-to-date noise policy is to reflect the lived experience of impacted communities more accurately. This paper will cover how communities experience aircraft noise in two separate noise exposure environments both near and away from airports, which practices are issues and most concerning to communities, what metrics more accurately evaluate impacts, and how a more community-centric approach provides a better representation of the aviation noise experienced by people, which is fundamental to operating a National Airspace System that works for all.

Suppressing Thermal Noise to Sub-Millikelvin Level in a Single-Spin Quantum System Using Realtime Frequency Tracking.

A single nitrogen-vacancy (NV) center in a diamond can be used as a nanoscale sensor for magnetic field, electric field or nuclear spins. Due to its low photon detection efficiency, such sensing processes often take a long time, suffering from an electron spin resonance (ESR) frequency fluctuation induced by the time-varying thermal perturbations noise. Thus, suppressing the thermal noise is the fundamental way to enhance single-sensor performance, which is typically achieved by utilizing a thermal control protocol with a complicated and highly costly apparatus if a millikelvin-level stabilization is required. Here, we analyze the real-time thermal drift and utilize an active way to alternately track the single-spin ESR frequency drift in the experiment. Using this method, we achieve a temperature stabilization effect equivalent to sub-millikelvin (0.8 mK) level with no extra environmental thermal control, and the spin-state readout contrast is significantly improved in long-lasting experiments. This method holds broad applicability for NV-based single-spin experiments and harbors the potential for prospective expansion into diverse nanoscale quantum sensing domains.

Decay-protected superconducting qubit with fast control enabled by integrated on-chip filters

Achieving fast gates and long coherence times for superconducting qubits presents challenges, typically requiring either a stronger coupling of the drive line or an excessively strong microwave signal to the qubit. To address this, we introduce on-chip filters of the qubit drive exhibiting a stopband at the qubit frequency, thus enabling long coherence times and strong coupling at the subharmonic frequency, facilitating fast single-qubit gates, and reduced thermal load. The filters exhibit an extrinsic relaxation time of a few seconds while enabling sub-10-ns gates with subharmonic control. Here we show up to 200-fold improvement in the measured relaxation time at the stopband. Furthermore, we implement subharmonic driving of Rabi oscillations with a π pulse duration of 12 ns. Our demonstration of on-chip filters and efficient subharmonic driving in a two-dimensional quantum processor paves the way for a scalable qubit architecture with reduced thermal load and noise from the control line.

Observation of the sliding phason mode of the incommensurate magnetic texture in Fe/Ir(111)

The nanoscopic magnetic texture forming in a monolayer of iron on the (111) surface of iridium, Fe/Ir(111), is spatially modulated and uniaxially incommensurate with respect to the crystallographic periodicities. As a consequence, a low-energy magnetic excitation is expected that corresponds to the sliding of the texture along the incommensurate direction, i.e., a phason mode, which we explicitly confirm with atomistic spin simulations. Using scanning tunneling microscopy (STM), we succeed to observe this phason mode experimentally. It can be excited by the STM tip, which leads to a random telegraph noise in the tunneling current that we attribute to the presence of two minima in the phason potential due to the presence of disorder in our sample. This provides the prospect of a floating phase in cleaner samples and, potentially, a commensurate-incommensurate transition as a function of external control parameters.

Quantum computer-enabled receivers for optical communication

Optical communication is the standard for high-bandwidth information transfer in today’s digital age. The increasing demand for bandwidth has led to the maturation of coherent transceivers that use phase- and amplitude-modulated optical signals to encode more bits of information per transmitted pulse. Such encoding schemes achieve higher information density, but also require more complicated receivers to discriminate the signaling states. In fact, achieving the ultimate limit of optical communication capacity, especially in the low light regime, requires coherent joint detection of multiple pulses. Despite their superiority, such joint detection receivers are not in widespread use because of the difficulty of constructing them in the optical domain. In this work we describe how optomechanical transduction of phase information from coherent optical pulses to superconducting qubit states followed by the execution of trained short-depth variational quantum circuits can perform joint detection of communication codewords with error probabilities that surpass all classical, individual pulse detection receivers. Importantly, we utilize a model of optomechanical transduction that captures non-idealities such as thermal noise and loss in order to understand the transduction performance necessary to achieve a quantum advantage with such a scheme. We also execute the trained variational circuits on an IBM-Q device with the modeled transduced states as input to demonstrate that a quantum advantage is possible even with current levels of quantum computing hardware noise.

Observation of the scaling dimension of fractional quantum Hall anyons

Unconventional quasiparticles emerging in the fractional quantum Hall regime1,2 present the challenge of observing their exotic properties unambiguously. Although the fractional charge of quasiparticles has been demonstrated for nearly three decades3–5, the first convincing evidence of their anyonic quantum statistics has only recently been obtained6,7 and, so far, the so-called scaling dimension that determines the propagation dynamics of the quasiparticles remains elusive. In particular, although the nonlinearity of the tunnelling quasiparticle current should reveal their scaling dimension, the measurements fail to match theory, arguably because this observable is not robust to non-universal complications8–12. Here we expose the scaling dimension from the thermal noise to shot noise crossover and observe an agreement with expectations. Measurements are fitted to the predicted finite-temperature expression involving both the scaling dimension of the quasiparticles and their charge12,13, in contrast to previous charge investigations focusing on the high-bias shot-noise regime14. A systematic analysis, repeated on several constrictions and experimental conditions, consistently matches the theoretical scaling dimensions for the fractional quasiparticles emerging at filling factors ν = 1/3, 2/5 and 2/3. This establishes a central property of fractional quantum Hall anyons and demonstrates a powerful and complementary window into exotic quasiparticles.

Mixed noise and posterior estimation with conditional deepGEM

We develop an algorithm for jointly estimating the posterior and the noise parameters in Bayesian inverse problems, which is motivated by indirect measurements and applications from nanometrology with a mixed noise model. We propose to solve the problem by an expectation maximization (EM) algorithm. Based on the current noise parameters, we learn in the E-step a conditional normalizing flow that approximates the posterior. In the M-step, we propose to find the noise parameter updates again by an EM algorithm, which has analytical formulas. We compare the training of the conditional normalizing flow with the forward and reverse Kullback–Leibler divergence, and show that our model is able to incorporate information from many measurements, unlike previous approaches.

Maximum enhancement of entanglement in cavity magnomechanics

Quantum entanglement constitutes a fundamental resource for many advanced information processing tasks. That is why it is crucial to develop innovative methods for generating and improving its degree in quantum systems. In this regard, cavity magnomechanics incorporating yttrium-iron-garnet (YIG) spheres emerges as a promising platform for achieving macroscopic entanglement between cavity microwave photons, magnons, and phonons. Here, we propose a novel scheme that utilizes both coherent feedback and an optical parametric amplifier (OPA) to maximally enhance bipartite entanglement in a hybrid system composed of a YIG sphere placed inside a microwave cavity. By properly tuning the feedback and OPA parameters, we demonstrate an optimal enhancement of cavity-magnon and cavity-phonon entanglements, surpassing the maximum values achievable with either feedback or OPA alone. Notably, our scheme not only enhances entanglement but also increases its robustness against thermal noise, enabling its survival up to hundreds of milliKelvins. These findings pave the way for designing sophisticated cavity magnomechanics experiments aimed at observing macroscopic entanglement, with far-reaching implications in quantum information science.

First upper limits on the 21 cm signal power spectrum from cosmic dawn from one night of observations with NenuFAR (Corrigendum)

The redshifted 21 cm signal from neutral hydrogen is a direct probe of the physics of the early universe and has been an important science driver of many present and upcoming radio interferometers. In this study we use a single night of observations with the New Extension in Nan cay Upgrading LOFAR (NenuFAR) to place upper limits on the 21 cm power spectrum from cosmic dawn at a redshift of $z$ = 20.3. NenuFAR is a new low-frequency radio interferometer, operating in the 10--85 MHz frequency range, currently under construction at the Nan cay Radio Observatory in France. It is a phased array instrument with a very dense $u coverage at short baselines, making it one of the most sensitive instruments for 21 cm cosmology analyses at these frequencies. Our analysis adopts the foreground subtraction approach, in which sky sources are modeled and subtracted through calibration and residual foregrounds are subsequently removed using Gaussian process regression. The final power spectra are constructed from the gridded residual data cubes in the $u plane. Signal injection tests are performed at each step of the analysis pipeline, the relevant pipeline settings are optimized to ensure minimal signal loss, and any signal suppression is accounted for through a bias correction on our final upper limits. We obtain a best 2sigma upper limit of $2.4 mK $ at $z$ = 20.3 and $k$ = 0.041 $h\ cMpc $. We see a strong excess power in the data, making our upper limits two orders of magnitude higher than the thermal noise limit. We investigate the origin and nature of this excess power and discuss further improvements to the analysis pipeline that can potentially mitigate it and consequently allow us to reach thermal noise sensitivity when multiple nights of observations are processed in the future.

Nonequilibrium quantum heat transport between structured environments

We apply the hierarchical equations of motion technique to analyzing nonequilibrium heat transport in a spin-boson type model, whereby heat transfer through a central spin is mediated by an intermediate pair of coupled harmonic oscillators. The coupling between each pair of oscillators is shown to introduce a localized gap into the effective spectral densities characterizing the system–oscillator–reservoir interactions. Compared to the case of a single mediating oscillator, we find the heat current to be drastically modified at weak system-bath coupling. In particular, a second-order treatment fails to capture the correct steady-state behavior in this regime, which stems from the λ 4-scaling of the energy transfer rate to lowest order in the coupling strength λ. This leads naturally to a strong suppression in the steady-state current in the asymptotically weak coupling limit. On the other hand, the current noise follows the same scaling as in the single oscillator case in accordance with the fluctuation-dissipation theorem. Additionally, we find the heat current to be consistent with Fourier’s law even at large temperature bias. Our analysis highlights a novel mechanism for controlling heat transport in nanoscale systems based on tailoring the spectral properties of thermal environments.

Barrier crossing in a viscoelastic medium under active noise: Predictions of Kramers’ flux-over-population method

The biochemical activity inside a cell has recently been suggested to act as a source of hydrodynamic fluctuations that can speed up or slow down enzyme catalysis [Tripathi et al., Commun. Phys. 5, 101 (2022).] The idea has been tested against and largely corroborated by simulations of activated barrier crossing in a simple fluid in the presence of thermal and athermal noise. The present paper attempts a wholly analytic solution to the same noise-driven barrier crossing problem but generalizes it to include viscoelastic memory effects of the kind likely to be present in cellular interiors. A calculation of the model’s barrier crossing rate, using Kramers’ flux-over-population formalism, reveals that in relation to the case where athermal noise is absent, athermal noise always accelerates barrier crossing, though the extent of enhancement depends on the duration τ0 over which the noise acts. More importantly, there exists a critical τ0—determined by the properties of the medium—at which Kramers’ theory breaks down and, on approach to which, the rate grows significantly. The possibility of such a giant enhancement is potentially open to experimental validation using optically trapped nanoparticles in viscoelastic media that are acted on by externally imposed colored noise.

A low noise CLASS AB operational amplifier with high voltage output capability by 180 nm BCD process

Abstract In this work, a low noise CLASS AB operational amplifier, which can output high voltage, has been fabricated by a 180 nm BCD process. For the objective of achieving low noise, the bipolar junction transistor (BJT) input stage with the base current compensation structure is employed. Experimental results show that the low noise amplifier’s equivalent input current and voltage noise are 3.2 pA/sqrt (Hz) and 16.73 nV/sqrt (Hz) separately, and the rising and falling slew rates are 10.40 MV/s and 6.67 MV/s separately. With the die area of 0.629 mm2, the amplifier’s power consumption is 18.3 mW, which flows 60 μA on the 5 V low power supply and 600 μA on the 25 V high power supply.

Modeling Thermal Infrared Image Degradation and Real-World Super-Resolution Under Background Thermal Noise and Streak Interference

Modeling Thermal Infrared Image Degradation and Real-World Super-Resolution Under Background Thermal Noise and Streak Interference

Memory-induced absolute negative mobility

Non-Markovian systems form a broad area of physics that remains greatly unexplored despite years of intensive investigations. The spotlight is on memory as a source of effects that are absent in their Markovian counterparts. In this work, we dive into this problem and analyze a driven Brownian particle moving in a spatially periodic potential and exposed to correlated thermal noise. We show that the absolute negative mobility effect, in which the net movement of the particle is in the direction opposite to the average force acting on it, may be induced by the memory of the setup. To explain the origin of this phenomenon, we resort to the recently developed effective mass approach to dynamics of non-Markovian systems.

High-precision high-speed nanopore ping-pong control system based on field programmable gate array.

"Molecular ping-pong," emerging as a control strategy in solid-state nanopore technology, presents a highly promising approach for repetitive measurements of single biomolecules, such as DNA. This paper introduces a high-precision, high-speed nanopore molecular ping-pong control system consisting of a home-built trans-impedance amplifier (TIA), a control system based on a Field Programmable Gate Array (FPGA), and a LabVIEW program operating on the host personal computer. Through feedback compensation and post-stage boosting, the TIA achieves a high bandwidth of about 200kHz with a gain of 100 MΩ, along with low input-referred current noise of 1.6 × 10-4pA2/Hz at 1kHz and 1.1 × 10-3pA2/Hz at 100kHz. The FPGA-based control system demonstrates a minimum overall response time (tdelay) of 6.5 μs from the analog input current signal trigger to the subsequent reversal of the analog output drive voltage signal, with a control precision of 1 μs. Additionally, a LabVIEW program has been developed to facilitate rapid data exchange and communication with the FPGA program, enabling real-time signal monitoring, parameter adjustment, and data storage. Successful recapture of individual DNA molecules at various tdelay, resulting in an improvement in capture rate by up to 2 orders of magnitude, has been demonstrated. With unprecedented control precision and capture efficiency, this system provides robust technical support and opens novel research avenues for nanopore single-molecule sensing and manipulation.

In Ukrainian

Brownian motors belong to the class of nanoscale devices that use the thermal noise of the environment as one of the necessary components in the mechanism of their operation. Today, there are a lot of practical implementations of such nanomachines, both inorganic, fairly simple mechanisms produced artificially, and more complex ones created from separate biological components available at the cellular level. One of the options for implementing the mechanism of straightening the chaotic thermal noise of the environment into unidirectional motion is the presence of a motor particle in the field of action of an asymmetric periodic stationary potential, which undergoes certain small disturbances (fluctuations) periodically over time. To describe such asymmetric one-dimensional structures (for example, dipole chains or fibers of the cytoskeleton) in the theory of Brownian motors, two model potentials are most often used: piecewise linear sawtooth and double sinusoidal. In this work, within the framework of the approximation of small fluctuations, a model of a pulsating Brownian motor with a stationary double sinusoidal potential and a disturbing small harmonic signal is considered. A new method of parametrization of such a problem is proposed, which allows to separate the contributions from various factors affecting the operation of the ratchet, and the numerical procedure for calculating the average speed of the directional movement of nanoparticles for the selected type of model potentials is specified. A number of numerical dependences of the average speed on the main parameters of the system were obtained. Peculiarities of the behavior of the motor as dependent on the parameter responsible for asymmetry and the number of potential wells on the spatial period of the stationary potential have been investigated. It is shown that the direction of the generated flux of nanoparticles depends not only on the phase shift between the stationary and fluctuating components of the potential, but also on the temperature of the system and the frequency of fluctuations, i.e., a possibility of temperature-frequency control of the direction of movement in the considered model has been found. Diagrams have been constructed that allow you to choose the ratio between the parameters of the nanomotor to create a flux of particles in the desired direction.

Copycat perceptron: Smashing barriers through collective learning.

We characterize the equilibrium properties of a model of y coupled binary perceptrons in the teacher-student scenario, subject to a suitable cost function, with an explicit ferromagnetic coupling proportional to the Hamming distance between the students' weights. In contrast to recent works, we analyze a more general setting in which thermal noise is present that affects each student's generalization performance. In the nonzero temperature regime, we find that the coupling of replicas leads to a bend of the phase diagram towards smaller values of α: This suggests that the free entropy landscape gets smoother around the solution with perfect generalization (i.e., the teacher) at a fixed fraction of examples, allowing standard thermal updating algorithms such as Simulated Annealing to easily reach the teacher solution and avoid getting trapped in metastable states as happens in the unreplicated case, even in the computationally easy regime of the inference phase diagram. These results provide additional analytic and numerical evidence for the recently conjectured Bayes-optimal property of Replicated Simulated Annealing for a sufficient number of replicas. From a learning perspective, these results also suggest that multiple students working together (in this case reviewing the same data) are able to learn the same rule both significantly faster and with fewer examples, a property that could be exploited in the context of cooperative and federated learning.

Noise behavior in GaAs0.2Sb0.8/GaSb heterojunction Source-All-Around vertical Tunnel FET: A comprehensive study

This article offers a comprehensive noise analysis of a GaAs0.2Sb0.8/GaSb heterojunction Source-All-Around Vertical Tunnel FET (SAA-VTFET), examining generation-recombination (GRN), flicker (FN), and diffusion (DN) noise. It pioneers an investigation into noise behavior under the influence of interface traps, temperature variations, and frequencies. Analysis includes both output current noise power spectral density (Sid) and input voltage noise power spectral density (Svg). Furthermore, the sensitivity of noise PSD is noted to be maximum at lower Vgs (gate bias voltage), suggesting that trap-assisted tunneling (TAT) and Shockley-Read-Hall (SRH) recombination dominate over band-to-band tunneling in this region. For enhanced clarity, this study also includes an analysis of the impact of traps and temperature on both AC and DC characteristics.