Showing papers on "Noise (electronics) published in 2004"
TL;DR: In this article, the behavior of excitable systems driven by Gaussian white noise is reviewed, focusing mainly on those general properties of such systems that are due to noise, and present several applications of their findings in biophysics and lasers.
1,373 citations
TL;DR: In this article, a feed-forward noise-canceling technique is proposed to cancel the noise and distortion contributions of the matching device, which allows for designing wide-band impedance-matching amplifiers with noise figure (NF) well below 3 dB.
Abstract: Known elementary wide-band amplifiers suffer from a fundamental tradeoff between noise figure (NF) and source impedance matching, which limits the NF to values typically above 3 dB. Global negative feedback can be used to break this tradeoff, however, at the price of potential instability. In contrast, this paper presents a feedforward noise-canceling technique, which allows for simultaneous noise and impedance matching, while canceling the noise and distortion contributions of the matching device. This allows for designing wide-band impedance-matching amplifiers with NF well below 3 dB, without suffering from instability issues. An amplifier realized in 0.25-/spl mu/m standard CMOS shows NF values below 2.4 dB over more than one decade of bandwidth (i.e., 150-2000 MHz) and below 2 dB over more than two octaves (i.e., 250-1100 MHz). Furthermore, the total voltage gain is 13.7 dB, the -3-dB bandwidth is from 2 MHz to 1.6 GHz, the IIP2 is +12 dBm, and the IIP3 is 0 dBm. The LNA drains 14 mA from a 2.5-V supply and the die area is 0.3/spl times/0.25 mm/sup 2/.
749 citations
TL;DR: In this paper, a modulated flux of atoms was adsorbed upon the surface of a 32.8 MHz NEMS resonator within an ultrahigh-vacuum environment, and the mass-induced resonance frequency shifts by these adsorbates were then measured to ascertain a mass sensitivity of 2.53×10−18g.
Abstract: We describe the application of nanoelectromechanical systems (NEMS) to ultrasensitive mass detection. In these experiments, a modulated flux of atoms was adsorbed upon the surface of a 32.8 MHz NEMS resonator within an ultrahigh-vacuum environment. The mass-induced resonance frequency shifts by these adsorbates were then measured to ascertain a mass sensitivity of 2.53×10^–18 g. In these initial measurements, this sensitivity is limited by the noise in the NEMS displacement transducer; the ultimate limits of the technique are set by fundamental phase noise processes. Our results and analysis indicate that mass sensing of individual molecules will be realizable with optimized NEMS devices.
612 citations
TL;DR: Thermal noise in a rigid reference cavity used for frequency stabilization of lasers is evaluated, based on the mechanical loss of cavity materials and the numerical analysis of the mirror-spacer mechanics with the direct application of the fluctuation dissipation theorem, to set a fundamental limit for frequency stability.
Abstract: We evaluate thermal noise (Brownian motion) in a rigid reference cavity used for frequency stabilization of lasers, based on the mechanical loss of cavity materials and the numerical analysis of the mirror-spacer mechanics with the direct application of the fluctuation dissipation theorem. This noise sets a fundamental limit for the frequency stability achieved with a rigid frequency-reference cavity of order 1 Hz/ square root Hz (0.01 Hz/ square root Hz) at 10 mHz (100 Hz) at room temperature. This level coincides with the world-highest level stabilization results.
520 citations
06 Jun 2004
TL;DR: In this paper, a modified derivative-superposition (DS) method was proposed to increase the maximum IIP3 at RF frequencies, which was used in a 0.25mum Si CMOS low-noise amplifier (LNA) designed for cellular code-division multiple access receivers.
Abstract: Intermodulation distortion in field-effect transistors (FETs) at RF frequencies is analyzed using the Volterra-series analysis. The degrading effect of the circuit reactances on the maximum IIP3 in the conventional derivative-superposition (DS) method is explained. The noise performance of this method is also analyzed and the effect of the subthreshold biasing of one of the FETs on the noise figure (NF) is shown. A modified DS method is proposed to increase the maximum IIP3 at RF. It was used in a 0.25-mum Si CMOS low-noise amplifier (LNA) designed for cellular code-division multiple-access receivers. The LNA achieved +22-dBm IIP3 with 15.5-dB gain, 1.65-dB NF, and 9.3 mA@2.6-V power consumption
366 citations
TL;DR: In this paper, the density-density correlations in the image of an expanding gas cloud are used to probe complex many-body states of trapped ultracold atoms, and the feasibility of the method is investigated by analysis of the relevant signal to noise ratio including experimental imperfections.
Abstract: We propose to utilize density-density correlations in the image of an expanding gas cloud to probe complex many-body states of trapped ultracold atoms. In particular, we show how this technique can be used to detect superfluidity of fermionic gases and to study spin correlations of multicomponent atoms in optical lattices. The feasibility of the method is investigated by analysis of the relevant signal to noise ratio including experimental imperfections.
334 citations
TL;DR: In this article, a CMOS capacitive sensing amplifier for a monolithic MEMS accelerometer fabricated by post-CMOS surface micromachining is described, which employs capacitance matching with optimal transistor sizing to minimize sensor noise floor.
Abstract: This paper describes a CMOS capacitive sensing amplifier for a monolithic MEMS accelerometer fabricated by post-CMOS surface micromachining. This chopper stabilized amplifier employs capacitance matching with optimal transistor sizing to minimize sensor noise floor. Offsets due to sensor and circuit are reduced by ac offset calibration and dc offset cancellation based on a differential difference amplifier (DDA). Low-duty-cycle periodic reset is used to establish robust dc bias at the sensing electrodes with low noise. This work shows that continuous-time voltage sensing can achieve lower noise than switched-capacitor charge integration for sensing ultra-small capacitance changes. A prototype accelerometer integrated with this circuit achieves 50-/spl mu/g//spl radic/Hz acceleration noise floor and 0.02-aF//spl radic/Hz capacitance noise floor while chopped at 1 MHz.
307 citations
TL;DR: It is shown that a wide class of uncoupled limit-cycle oscillators can be in-phase synchronized by common weak additive noise, and an expression of the Lyapunov exponent is analytically derived to study the stability of the noise-driven synchronizing state.
Abstract: We show that a wide class of uncoupled limit-cycle oscillators can be in-phase synchronized by common weak additive noise. An expression of the Lyapunov exponent is analytically derived to study the stability of the noise-driven synchronizing state. The result shows that such a synchronization can be achieved in a broad class of oscillators with little constraint on their intrinsic property. On the other hand, the leaky integrate-and-fire neuron oscillators do not belong to this class, generating intermittent phase slips according to a power law distribution of their intervals.
306 citations
TL;DR: In this article, the effect of beat noise and other types of additive noise in time-spreading optical-code-division multiple access (TS-OCDMA) networks is analyzed.
Abstract: The effect of beat noise and other types of additive noise in time-spreading optical-code-division multiple-access (TS-OCDMA) networks is analyzed in this paper. By defining the coherent ratio kt, the ratio of the chip duration to the coherence time of the light source, TS-OCDMA systems are classified into incoherent, partially coherent, and coherent systems. The noise distributions and the bit-error rates are derived, and system performance is discussed for different cases. The performance of coherent systems is limited by the beat noise. With increasing kt, the effect of beat noise decreases in incoherent systems, and they eventually become free of beat noise. Possible solutions to the beat noise problem in coherent and partially coherent systems are also proposed and discussed.
303 citations
TL;DR: It is found that the dominant energy relaxation process is a spontaneous emission induced by quantum noise coupled to the charge degree of freedom, roughly proportional to the qubit excitation energy.
Abstract: We study decoherence of the Josephson charge qubit by measuring energy relaxation and dephasing with help of the single-shot readout. We found that the dominant energy relaxation process is a spontaneous emission induced by quantum noise coupled to the charge degree of freedom. Spectral density of the noise at high frequencies is roughly proportional to the qubit excitation energy.
267 citations
TL;DR: In this article, the excitation of a plasma antenna using an argon surface wave discharge operating at 500 MHz with RF power levels up to 120 W and gas pressures between 0.03 and 0.5 mb was examined.
Abstract: This experimental and theoretical study examines the excitation of a plasma antenna using an argon surface wave discharge operating at 500 MHz with RF power levels up to 120 W and gas pressures between 0.03 and 0.5 mb. The results show that the length of the plasma column increases as the square root of the applied power and that the plasma density decreases linearly from the wave launcher to the end of the plasma column. These results are consistent with a simple global model of the antenna. Since noise is critical to communication systems, the noise generated by the plasma was measured from 10 to 250 MHz. Between 50 and 250 MHz the excess noise temperature was found to be 17.2/spl plusmn/1.0 dB above 290 K. This corresponds to an ohmic thermal noise source at 1.4/spl plusmn/0.3 eV, compared with an electron temperature of 1.65 eV predicted by the global model. Estimates of the electrical conductivity of the plasma column based on measured electron number densities lead to an antenna efficiency of about 65% at a transmission frequency of 100 MHz and an increase in total antenna noise of 1 dB due to the plasma. Theoretical modeling and experimental observations of the radiation pattern of the antenna show that the linear variation of conductivity and finite resistance of the column lead to a reduction in the depth of the nulls in the radiation pattern and a consequent increase in the width of the main lobe.
TL;DR: Computer algorithms for reference signal delay and compression are discussed as replacements for the classical delay line implementation and the ambiguity function and the statistical characteristics of the correlation output for the latter configuration are further analyzed.
Abstract: Pulse compression radar is used in a great number of applications. Excellent range resolution and high electronic counter-countermeasures performance is achieved by wideband long pulses, which spread out the transmitted energy in frequency and time. By using a random noise waveform, the range ambiguity is suppressed as well. In most applications, the random signal is transmitted directly from a noise-generating microwave source. A sine wave, which is phase or frequency modulated by random noise, is an alternative, and in this paper, the ambiguity function and the statistical characteristics of the correlation output for the latter configuration are further analyzed. Range resolution is then improved because the noise bandwidth of the modulated carrier is wider than that of the modulating signal, and the range sidelobes are also further suppressed. Random biphase modulation gives a 4-dB (/spl pi//sup 2//4) improvement, but much higher sidelobe suppression could be achieved using continuous phase/frequency modulation. Due to the randomness of the waveform, the output correlation integral is accompanied by a noise floor, which limits the possible sidelobe suppression as determined by the time-bandwidth product. In synthetic aperture radar (SAR) applications with distributed targets, this product should be large compared with the number of resolution elements inside the antenna main beam. The advantages of low range sidelobes and enhanced range resolution make frequency/phase-modulated noise radar attractive for many applications, including SAR mapping, surveillance, altimetry, and scatterometry. Computer algorithms for reference signal delay and compression are discussed as replacements for the classical delay line implementation.
TL;DR: In this article, a 1.8-V 15-bit 40-MSample/s CMOS pipelined analog-to-digital converter with 90-dB spurious-free dynamic range (SFDR) and 72-dB peak SNR over the full Nyquist band is presented.
Abstract: A 1.8-V 15-bit 40-MSample/s CMOS pipelined analog-to-digital converter with 90-dB spurious-free dynamic range (SFDR) and 72-dB peak signal-to-noise ratio (SNR) over the full Nyquist band is presented. Its differential and integral nonlinearities are 0.25 LSB and 1.5 LSB, respectively, and its power consumption is 400 mW. This performance is enabled by digital background calibration of internal digital-to-analog converter (DAC) noise and interstage gain errors. The calibration achieves improvements of better than 12 dB in signal-to-noise plus distortion ratio and 20 dB in SFDR relative to the case where calibration is disabled. Other enabling features of the prototype integrated circuit (IC) include a low-latency, segmented, dynamic element-matching DAC, distributed passive input signal sampling, and asymmetric clocking to maximize the time available for the first-stage residue amplifier to settle. The IC is realized in a 0.18-/spl mu/m mixed-signal CMOS process and has a die size of 4mm/spl times/5 mm.
TL;DR: The effect of noise on images obtained using quantitative phase‐amplitude microscopy is explored and an approach that allows good‐quality quantitative phase retrieval to be obtained even for very noisy data is proposed.
Abstract: We explore the effect of noise on images obtained using quantitative phase-amplitude microscopy - a new microscopy technique based on the determination of phase from the intensity evolution of propagating radiation. We compare the predictions with experimental results and also propose an approach that allows good-quality quantitative phase retrieval to be obtained even for very noisy data.
TL;DR: In this article, a general circuit model is derived for the electrical noise of electrode-electrolyte systems, with emphasis on its implications for electrochemical sensors, and the noise power spectral densities associated with all noise sources introduced in the model are also analytically calculated.
Abstract: A general circuit model is derived for the electrical noise of electrode–electrolyte systems, with emphasis on its implications for electrochemical sensors. The noise power spectral densities associated with all noise sources introduced in the model are also analytically calculated. Current and voltage fluctuations in typical electrode–electrolyte systems are demonstrated to originate from either thermal equilibrium noise created by conductors, or nonequilibrium excess noise caused by charge transfer processes produced by electrochemical interactions. The power spectral density of the thermal equilibrium noise is predicted using the fluctuation-dissipation theorem of thermodynamics, while the excess noise is assessed in view of charge transfer kinetics, along with mass transfer processes in the electrode proximity. The presented noise model not only explains previously reported noise spectral densities such as thermal noise in sensing electrodes, shot noise in electrochemical batteries, and 1/f noise in corrosive interfaces, it also provides design-oriented insight into the fabrication of low-noise micro- and nanoelectrochemical sensors.
TL;DR: It is shown that low frequency noise sources, such as seed noise, pump noise, and detuning fluctuations, present in optical parametric amplifiers, have negligible effect on squeezing produced by a below-threshold OPO.
Abstract: We demonstrate the generation of broadband continuous-wave optical squeezing from 280 Hz-100 kHz using a below-threshold optical parametric oscillator (OPO). The squeezed state phase was controlled using a noise locking technique. We show that low frequency noise sources, such as seed noise, pump noise, and detuning fluctuations, present in optical parametric amplifiers, have negligible effect on squeezing produced by a below-threshold OPO. This low frequency squeezing is ideal for improving the sensitivity of audio frequency measuring devices such as gravitational-wave detectors.
TL;DR: In this paper, the performance of microcantilevers as uncooled infrared detectors with optical readout was examined and it was shown that temperature fluctuation and background fluctuation noise are fundamental limits to the performance.
Abstract: It has recently been shown that bimaterial microcantilevers can be used as uncooled infrared detectors. Bimaterial microcantilevers deform as their temperature changes due to the absorption of infrared photons. Infrared imaging using uncooled cantilever arrays has already been achieved by a number of groups. In this paper, we examined the performance of microcantilevers as uncooled infrared detectors with optical readout. As in the case of other kinds of uncooled thermal infrared detectors, temperature fluctuation noise and background fluctuation noise are fundamental limits to the performance of microcantilever thermal detectors. Since microcantilevers are mechanical devices, thermo-mechanical noise will also influence their performance. We fabricated a SiNx microcantilever thermal detector with an Al layer in the bimaterial region. For the microcantilever geometry and materials used, the background fluctuation noise equivalent temperature difference, NETDBF, calculated for f/1 optics and a 30 Hz frame rate was found to be 1.26 mK. The NETDTF, limited by temperature fluctuation noise, was calculated to be 7.4 mK while the thermo-mechanical NETDTM was calculated to be 5.3 mK. The sum of all fundamental noise sources, including the intrinsic noise of the “optical lever” readout, results in a total NETD of 9.2 mK. Absence of the readout noise would improve this parameter by only 2%.
TL;DR: A review of the recent progress in APD technology can be found in this paper, where the authors present a survey of the most recent developments in III-V compound avalanche photodiodes (APDs).
Abstract: The development of high-performance optical receivers has been a primary driving force for research on III-V compound avalanche photodiodes (APDs). The evolution of fiber optic systems toward higher bit rates has pushed APD performance toward higher bandwidths, lower noise, and higher gain-bandwidth products. Utilizing thin multiplication regions has reduced the excess noise. Further noise reduction has been demonstrated by incorporating new materials and impact ionization engineering with beneficially designed heterostructures. High gain-bandwidth products have been achieved waveguide structures. Recently, imaging and sensing applications have spurred interest in low noise APDs in the infrared and the UV as well as large area APDs and arrays. This paper reviews some of the recent progress in APD technology.
TL;DR: Both the image signal‐to‐noise ratio (SNR) and the noise amplification (g‐factor) in sensitivity‐encoding (SENSE) parallel imaging applications were quantitatively evaluated and both the g‐factor and SNR improved substantially with n.
Abstract: The performance of a 16-channel receive-only RF coil for brain imaging at 3.0 Tesla was investigated using a custom-built 16-channel receiver. Both the image signal-to-noise ratio (SNR) and the noise amplification (g-factor) in sensitivity-encoding (SENSE) parallel imaging applications were quantitatively evaluated. Furthermore, the performance was compared with that of hypothetical coils with one, two, four, and eight elements (n) by combining channels in software during image reconstruction. As expected, both the g-factor and SNR improved substantially with n. Compared to an equivalent (simulated) single-element coil, the 16-channel coil showed a 1.87-fold average increase in brain SNR. This was mainly due to an increase in SNR in the peripheral brain (an up to threefold SNR increase), whereas the SNR increase in the center of the brain was 4%. The incremental SNR gains became relatively small at large n, with a 9% gain observed when n was increased from 8 to 16. Compared to the (larger) product birdcage head coil, SNR increased by close to a factor of 2 in the center, and by up to a factor of 6 in the periphery of the brain. For low SENSE acceleration (rate-2), g-factors leveled off for n>4, and improved only slightly (1.4% averaged over brain) going from n=8 to n=16. Improvements in g for n>8 were larger for higher acceleration rates, with the improvement for rate-3 averaging 12.0%.
TL;DR: In this article, various models of temporally correlated errors are developed and these provide relations between the power spectral density and the data covariance matrix, and these relations are applied to two-color electronic distance meter (EDM) measurements made frequently in California over the past 15-20 years.
Abstract: [1] Frequent, high-precision geodetic data have temporally correlated errors. Temporal correlations directly affect both the estimate of rate and its standard error; the rate of deformation is a key product from geodetic measurements made in tectonically active areas. Various models of temporally correlated errors are developed and these provide relations between the power spectral density and the data covariance matrix. These relations are applied to two-color electronic distance meter (EDM) measurements made frequently in California over the past 15-20 years. Previous analysis indicated that these data have significant random walk error. Analysis using the noise models developed here indicates that the random walk model is valid for about 30% of the data. A second 30% of the data can be better modeled with power law noise with a spectral index between 1 and 2, while another 30% of the data can be modeled with a combination of band-pass-filtered plus random walk noise. The remaining 10% of the data can be best modeled as a combination of band-pass-filtered plus power law noise. This band-pass-filtered noise is a product of an annual cycle that leaks into adjacent frequency bands. For time spans of more than 1 year these more complex noise models indicate that the precision in rate estimates is better than that inferred by just the simpler, random walk model of noise.
TL;DR: The time-division multiplexing operation of the relay channel in the wideband regime is analyzed and it is shown that time division does not achieve minimum energy per bit.
Abstract: We determine the capacity region of a degraded Gaussian relay channel with multiple relay stages. This is done by building an inductive argument based on the single-relay capacity theorem of Cover and El Gamal. For an arbitrary distribution of noise powers, we derive the optimal power distribution strategy among the transmitter and the relays and the best possible improvement in signal-to-noise ratio (SNR) that can be achieved from using a given number of relays. The time-division multiplexing operation of the relay channel in the wideband regime is analyzed and it is shown that time division does not achieve minimum energy per bit.
TL;DR: In this article, the authors present a theoretical analysis and the results of measurements of thermorefractive noise in microcavities, which may be considered direct observations of fundamental fluctuations of temperature in solid media.
Abstract: We present a theoretical analysis and the results of measurements of thermorefractive noise in microcavities. These measurements may be considered direct observations of fundamental fluctuations of temperature in solid media. Our experimentally measured noise spectra are in agreement with our theoretical model.
TL;DR: In this article, the Gordon-Mollenauer effect is compensated by subtracting from the received phase a correction proportional to the received intensity, and the optimal scaling factor is derived analytically and found to be approximately equal to half of the ratio of mean nonlinear phase noise and the mean received intensity.
Abstract: Nonlinear phase noise, often called the Gordon-Mollenauer effect, can be compensated electronically by subtracting from the received phase a correction proportional to the received intensity. The optimal scaling factor is derived analytically and found to be approximately equal to half of the ratio of mean nonlinear phase noise and the mean received intensity. Using optimal compensation, the standard deviation of residual phase noise is halved, doubling the transmission distance in systems limited by nonlinear phase noise.
TL;DR: In this article, an exact analysis for third-order charge-pump phase-locked loops using state equations is presented, and the effect of the loop parameters and the reference frequency on the loop phase margin and stability is analyzed.
Abstract: In this paper, we present an exact analysis for third-order charge-pump phase-locked loops using state equations. Both the large-signal lock acquisition process and the small-signal linear tracking behavior are described using this analysis. The nonlinear state equations are linearized for the small-signal condition and the z-domain noise transfer functions are derived. A comparison to some of the existing analysis methods such as the impulse-invariant transformation and s-domain analysis is provided. The effect of the loop parameters and the reference frequency on the loop phase margin and stability is analyzed. The analysis is verified using behavioral simulations in MATLAB and SPECTRE.
TL;DR: A general comprehensive stochastic model of the substrate and P/G noise sources in very large-scale integration (VLSI) circuits is proposed and a comparison between the results obtained by the mathematical model and those obtained by HSPICE simulation prove the accuracy of the predicted model.
Abstract: Phase-locked loops (PLL) in radio-frequency (RF) and mixed analog-digital integrated circuits (ICs) experience substrate coupling due to the simultaneous circuit switching and power/ground (P/G) noise which translate to a timing jitter. In this paper. an analysis of the PLL timing jitter due to substrate noise resulting from P/G noise and large-signal switching is presented. A general comprehensive stochastic model of the substrate and P/G noise sources in very large-scale integration (VLSI) circuits is proposed. This is followed by calculation of the phase noise of the constituent voltage-controlled oscillator (VCO) in terms of the statistical properties of substrate and P/G noise. The PLL timing jitter is then predicted in response to the VCO phase noise. Our mathematical method is utilized to study the jitter-induced P/G noise in a CMOS PLL, which is designed and simulated in a 0.25-/spl mu/m standard CMOS process. A comparison between the results obtained by our mathematical model and those obtained by HSPICE simulation prove the accuracy of the predicted model.
TL;DR: The study of the second-order asymptotic expansion of the input-output mutual information of multidimensional channels finds application in the analysis of the bandwidth-power tradeoff achieved by various signaling strategies in the wideband regime.
Abstract: A formula for the second-order expansion of the input-output mutual information of multidimensional channels as the signal-to-noise ratio (SNR) goes to zero is obtained. While the additive noise is assumed to be Gaussian, we deal with very general classes of input and channel distributions. As special cases, these channel models include fading channels, channels with random parameters, and channels with almost Gaussian noise. When the channel is unknown at the receiver, the second term in the asymptotic expansion depends not only on the covariance matrix of the input signal but also on the fourth mixed moments of its components. The study of the second-order asymptotics of mutual information finds application in the analysis of the bandwidth-power tradeoff achieved by various signaling strategies in the wideband regime.
TL;DR: In this article, the transient dynamics of these ecosystems are analyzed through generalized Lotka-Volterra equations in the presence of multiplicative noise, which models the interaction between the species and the environment.
Abstract: Noise, through its interaction with the nonlinearity of the living systems, can give rise to counter-intuitive phenomena such as stochastic resonance, noise-delayed extinction, temporal oscillations, and spatial patterns. In this paper we briefly review the noise-induced effects in three different ecosystems: (i) two
competing species; (ii) three interacting species, one predator and two preys, and
(iii) N-interacting species. The transient dynamics of these ecosystems are analyzed through generalized Lotka-Volterra equations in the presence of multiplicative
noise, which models the interaction between the species and the environment. The
interaction parameter between the species is random in cases (i) and (iii), and a
periodical function, which accounts for the environmental temperature, in case (ii).
We find noise-induced phenomena such as quasi-deterministic oscillations, stochastic
resonance, noise-delayed extinction, and noise-induced pattern formation with non-monotonic behaviors of patterns areas and of the density correlation as a function
of the multiplicative noise intensity. The asymptotic behavior of the time average of
the$ i^{th}$
population when the ecosystem is composed of a great number of interacting
species is obtained and the effect of the noise on the asymptotic probability distri-
butions of the populations is discussed.
TL;DR: In this paper, the influence of various noise sources on the dynamics of two-level systems at optimal operation points where the linear coupling to low-frequency fluctuations is suppressed is analyzed, focusing on the experimentally relevant $1/f$ and Ohmic power spectra.
Abstract: Motivated by recent experiments with Josephson-junction circuits, we analyze the influence of various noise sources on the dynamics of two-level systems at optimal operation points where the linear coupling to low-frequency fluctuations is suppressed. We study the decoherence due to nonlinear (quadratic) coupling, focusing on the experimentally relevant $1/f$ and Ohmic noise power spectra. For $1/f$ noise strong higher-order effects influence the evolution.
TL;DR: In this article, the scaling behavior of 1∕f noise in single-walled carbon nanotube devices was investigated and an empirical formula was established to describe this behavior over a wide range of device parameters that can be used to assess the noise characteristics of carbon-nanotube-based electronic devices.
Abstract: We report the scaling behavior of 1∕f noise in single-walled carbon nanotube devices. In this study we use two-dimensional carbon nanotube networks to explore the geometric scaling of 1∕f noise and find that for devices of a given resistance the noise scales inversely with device size. We have established an empirical formula that describes this behavior over a wide range of device parameters that can be used to assess the noise characteristics of carbon nanotube-based electronic devices and sensors.
Posted Content•
TL;DR: Noise-induced phenomena such as quasi-deterministic oscillations, stochastic resonance, noise-delayed extinction, and noise-induced pattern formation with nonmonotonic behaviors of patterns areas and of the density correlation are found as a function of the multiplicative noise intensity.
Abstract: Noise, through its interaction with the nonlinearity of the living systems, can give rise to counter-intuitive phenomena such as stochastic resonance, noise-delayed extinction, temporal oscillations, and spatial patterns. In this paper we briefly review the noise-induced effects in three different ecosystems: (i) two competing species; (ii) three interacting species, one predator and two preys, and (iii) N-interacting species. The transient dynamics of these ecosystems are analyzed through generalized Lotka-Volterra equations in the presence of multiplicative noise, which models the interaction between the species and the environment. The interaction parameter between the species is random in cases (i) and (iii), and a periodical function, which accounts for the environmental temperature, in case (ii). We find noise-induced phenomena such as quasi-deterministic oscillations, stochastic resonance, noise-delayed extinction, and noise-induced pattern formation with nonmonotonic behaviors of patterns areas and of the density correlation as a function of the multiplicative noise intensity. The asymptotic behavior of the time average of the \emph{$i^{th}$} population when the ecosystem is composed of a great number of interacting species is obtained and the effect of the noise on the asymptotic probability distributions of the populations is discussed.