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Low-frequency 1/f noise is ubiquitous, and dominates the signal-to-noise performance in nanodevices. Here we investigate the noise characteristics of single-layer and bilayer graphene nano-devices, and uncover an unexpected 1/f noise behavior for bilayer devices. Graphene is a single layer of graphite, where carbon atoms form a 2D honeycomb lattice. Despite the similar composition, bilayer graphene (two graphene monolayers stacked in the natural graphite order) is a distinct 2D system with a different band structure and electrical properties. In graphene monolayers, the 1/f noise is found to follow Hooge's empirical relation with a noise parameter comparable to that of bulk semiconductors. However, this 1/f noise is strongly suppressed in bilayer graphene devices, and exhibits an unusual dependence on the carrier density, different from most other materials. The unexpected noise behavior in graphene bilayers is associated with its unique band structure that varies with the charge distribution among the two layers, resulting in an effective screening of potential fluctuations due to external impurity charges. The findings here point to exciting opportunities for graphene bilayers in low-noise applications.

Bell System Technical Journal, 31: 5. September 1952 pp 950-975. Electrical Noise in Semiconductors. (Montgomery, H.C.)

The mechanism at the base of phase noise generation in electrical oscillators is reexamined from first principles. The well known Lorentzian spectral power distribution is obtained, together with a clearcut expression for the line-width parameter. The mechanism of suppression of the amplitude fluctuations and its effects are discussed and the true role of the figure of merit $Q_0$ of the resonator is restated. The up conversion of low frequency components from a non-white noise source is also considered. A number of simple numerical experiments is presented to illustrate and clarify the mathematical results.

Electrical noise measurement system measures noise generated by edge-type connectors and circuit cards when they are subjected to sinusoidal vibration. It provides a signal across the contact area and monitors the signal change during vibration. Noise measured can be expressed as a varying change in total contact resistance.

Folkscanomy Electronics Articles: Troubleshooting Electrical Noise

We theoretically study energy pumping processes in an electrical circuit with avalanche diodes, where non-Gaussian athermal noise plays a crucial role. We show that a positive amount of energy (work) can be extracted by an external manipulation of the circuit in a cyclic way, even when the system is spatially symmetric. We discuss the properties of the energy pumping process for both quasi-static and fnite-time cases, and analytically obtain formulas for the amounts of the work and the power. Our results demonstrate the significance of the non-Gaussianity in energetics of electrical circuits.

A thorough analysis was performed to evaluate the advantage of power Ldmos RF transistors built on SOI substrate versus bulk silicon substrate. It had been anticipated a significant improvement would be realized with SOI due to the lower inherent parasitic capacitances. The disadvantage of SOI would be its inability to dissipate heat as well as bulk silicon. Extensive data was taken to generate device models. RF simulations comparing simulated to actual verified these models. Our observation is that at the frequency of 1 GHz where the study was made, the advantage of lower parasitic capacitance is not apparent. There is an offset to this advantage due by the higher drain to gate feedback capacitance in the SOI process. The other disadvantage of SOI which is poorer heat dissipation played slightly to lower the performance. Overall the results showed that at the frequency and power levels studied, SOI did not provide an advantage over bulk silicon devices. Several publications have been derived from this work.

Electrical noise and cross talk generated during explosive testing by gage and cable destruction were investigated. Results indicate that the primary instrumentation parameters affecting noise and cross talk levels are cable type, transducer bridge symmetry and its effects on signal conditioner common mode rejection ratio, and the degree of isolation between conditioner power circuits.

Electrical noise and cross talk generated during explosive testing by gage and cable destruction were investigated. Results indicate that the primary instrumentation parameters affecting noise and cross talk levels are cable type, transducer bridge symmetry and its effects on signal conditioner common mode rejection ratio, and the degree of isolation between conditioner power circuits.

Electrical noise and cross talk generated during explosive testing by gage and cable destruction were investigated. Results indicate that the primary instrumentation parameters affecting noise and cross talk levels are cable type, transducer bridge symmetry and its effects on signal conditioner common mode rejection ratio, and the degree of isolation between conditioner power circuits.

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We have measured the resistance noise of copper metallic wires during a tensile stress. The time variation of the main resistance is continuous up to the wire breakdown, but its fluctuations reveal the intermittent and heterogeneous character of plastic flow. We show in particular direct correlations between strengthening mechanisms and noise spectra characteristics.

Electrical noise and cross talk generated during explosive testing by gage and cable destruction were investigated. Results indicate that the primary instrumentation parameters affecting noise and cross talk levels are cable type, transducer bridge symmetry and its effects on signal conditioner common mode rejection ratio, and the degree of isolation between conditioner power circuits.

The electric thermal noise has been measured in two aging materials, a colloidal suspension (Laponite) and a polymer (polycarbonate), presenting very slow relaxation towards equilibrium. The measurements have been performed during the transition from a fluid-like to a solid-like state for the gel and after a quench for the polymer. For both materials we have observed that the electric noise is characterized by a strong intermittency, which induces a large violation of the Fluctuation Dissipation Theorem (FDT) during the aging time, and may persist for several hours at low frequency. The statistics of these intermittent signals and their dependance on the quench speed for the polymer or on sample concentration for the gel are studied. The results are in a qualitative agreement with recent models of aging, that predict an intermittent dynamics.

The electric thermal noise has been measured in two aging materials, a colloidal suspension (Laponite) and a polymer (polycarbonate), presenting very slow relaxation towards equilibrium. The measurements have been performed during the transition from a fluid-like to a solid-like state for the gel and after a quench for the polymer. For both materials we have observed that the electric noise is characterized by a strong intermittency, which induces a large violation of the Fluctuation Dissipation Theorem (FDT) during the aging time, and may persist for several hours at low frequency. The statistics of these intermittent signals and their dependance on the quench speed for the polymer or on sample concentration for the gel are studied. The results are in a qualitative agreement with recent models of aging, that predict an intermittent dynamics.

The electric thermal noise has been measured in two aging materials, a colloidal suspension (Laponite) and a polymer (polycarbonate), presenting very slow relaxation towards equilibrium. The measurements have been performed during the transition from a fluid-like to a solid-like state for the gel and after a quench for the polymer. For both materials we have observed that the electric noise is characterized by a strong intermittency, which induces a large violation of the Fluctuation Dissipation Theorem (FDT) during the aging time, and may persist for several hours at low frequency. The statistics of these intermittent signals and their dependance on the quench speed for the polymer or on sample concentration for the gel are studied. The results are in a qualitative agreement with recent models of aging, that predict an intermittent dynamics.

Electrical noise and cross talk generated during explosive testing by gage and cable destruction were investigated. Results indicate that the primary instrumentation parameters affecting noise and cross talk levels are cable type, transducer bridge symmetry and its effects on signal conditioner common mode rejection ratio, and the degree of isolation between conditioner power circuits.

In order to promote public education and public safety, equal justice for all, a better informed citizenry, the rule of law, world trade and world peace, this legal document is hereby made available on a noncommercial basis, as it is the right of all humans to know and speak the laws that govern them. (For more information: 12 Tables of Code ) Name of Legally Binding Document: GB 19606-103: Noise limit value for household and similar electrical appliances- Particular requirements for electric massager Name of Standards Organization: Standardization Administration of China (SAC) LEGALLY BINDING DOCUMENT

In order to promote public education and public safety, equal justice for all, a better informed citizenry, the rule of law, world trade and world peace, this legal document is hereby made available on a noncommercial basis, as it is the right of all humans to know and speak the laws that govern them. (For more information: 12 Tables of Code ) Name of Legally Binding Document: GB 19606-3: Noise limit value for household and similar electrical appliances —Particular requirements for dishwashers Name of Standards Organization: Standardization Administration of China (SAC) LEGALLY BINDING DOCUMENT

In order to promote public education and public safety, equal justice for all, a better informed citizenry, the rule of law, world trade and world peace, this legal document is hereby made available on a noncommercial basis, as it is the right of all humans to know and speak the laws that govern them. (For more information: 12 Tables of Code ) Name of Legally Binding Document: GB 19606-3: Noise limit value for household and similar electrical appliances —Particular requirements for dishwashers Name of Standards Organization: Standardization Administration of China (SAC) LEGALLY BINDING DOCUMENT

Bibliography: p. [483]-487

From a quantum point of view, it is mandatory to include the measurement process when predicting the time-evolution of a quantum system. In this paper, a model to treat the measurement of the (TeraHertz) THz electrical current in quantum devices is presented. The explicit interaction of a quantum system with an external measuring apparatus is analyzed through the unambiguous notion of the Bohmian conditional wave function, the wave function of a subsystem. It it shown that such THz quantum measurement process can be modeled as a weak measurement: The systems suffers a small perturbation due to the apparatus, but the current is measured with a great uncertainty. This uncertainty implies that a new source of noise appears at THz frequencies. Numerical (quantum Monte Carlo) experiments are performed confirming the weak character of this measurement. This work also indicates that at low frequencies this noise is negligible and it can be ignored. From a classical point of view, the origin of this noise due to the measurement at THz frequencies can be attributed to the plasmonic effect of those electrons at the contacts (by interpreting the contacts themselves as part of the measuring apparatus).

We investigate the visibility of the current and shot-noise correlations of electrical analogs of the optical Mach-Zehnder interferometer and the Hanbury Brown Twiss interferometer. The electrical analogs are discussed in conductors subject to high magnetic fields where electron motion is along edge states. The transport quantities are modulated with the help of an Aharonov-Bohm flux. We discuss the conductance (current) visibility and shot noise visibility as a function of temperature and applied voltage. Dephasing is introduced with the help of fictitious voltage probes. Comparison of these two interferometers is of interest since the Mach-Zehnder interferometer is an amplitude (single-particle) interferometer whereas the Hanbury Brown Twiss interferometer is an intensity (two-particle) interferometer. A direct comparison is only possible for the shot noise of the two interferometers. We find that the visibility of shot noise correlations of the Hanbury Brown Twiss interferometer as function of temperature, voltage or dephasing, is qualitatively similar to the visibility of the first harmonic of the shot noise correlation of the Mach-Zehnder interferometer. In contrast, the second harmonic of the shot noise visibility of the Mach-Zehnder interferometer decreases much more rapidly with increasing temperature, voltage or dephasing rate.

We investigate the visibility of the current and shot-noise correlations of electrical analogs of the optical Mach-Zehnder interferometer and the Hanbury Brown Twiss interferometer. The electrical analogs are discussed in conductors subject to high magnetic fields where electron motion is along edge states. The transport quantities are modulated with the help of an Aharonov-Bohm flux. We discuss the conductance (current) visibility and shot noise visibility as a function of temperature and applied voltage. Dephasing is introduced with the help of fictitious voltage probes. Comparison of these two interferometers is of interest since the Mach-Zehnder interferometer is an amplitude (single-particle) interferometer whereas the Hanbury Brown Twiss interferometer is an intensity (two-particle) interferometer. A direct comparison is only possible for the shot noise of the two interferometers. We find that the visibility of shot noise correlations of the Hanbury Brown Twiss interferometer as function of temperature, voltage or dephasing, is qualitatively similar to the visibility of the first harmonic of the shot noise correlation of the Mach-Zehnder interferometer. In contrast, the second harmonic of the shot noise visibility of the Mach-Zehnder interferometer decreases much more rapidly with increasing temperature, voltage or dephasing rate.

We present a study of the numerical solution of the two dimensional electrical impedance tomography problem, with noisy measurements of the Dirichlet to Neumann map. The inversion uses parametrizations of the conductivity on optimal grids. The grids are optimal in the sense that finite volume discretizations on them give spectrally accurate approximations of the Dirichlet to Neumann map. The approximations are Dirichlet to Neumann maps of special resistor networks, that are uniquely recoverable from the measurements. Inversion on optimal grids has been proposed and analyzed recently, but the study of noise effects on the inversion has not been carried out. In this paper we present a numerical study of both the linearized and the nonlinear inverse problem. We take three different parametrizations of the unknown conductivity, with the same number of degrees of freedom. We obtain that the parametrization induced by the inversion on optimal grids is the most efficient of the three, because it gives the smallest standard deviation of the maximum a posteriori estimates of the conductivity, uniformly in the domain. For the nonlinear problem we compute the mean and variance of the maximum a posteriori estimates of the conductivity, on optimal grids. For small noise, we obtain that the estimates are unbiased and their variance is very close to the optimal one, given by the Cramer-Rao bound. For larger noise we use regularization and quantify the trade-off between reducing the variance and introducing bias in the solution. Both the full and partial measurement setups are considered.

It is proposed to measure the current noise generated in a mesoscopic conductor by macroscopic quantum tunneling (MQT) in a current biased Josephson junction placed in parallel to the conductor. The theoretical description of this set-up takes into account the complete dynamics of detector and noise source. Explicit results are given for the specific case of current fluctuations in an oxide layer tunnel junction, and it is shown how the device allows to extract the fourth order cumulant of the noise from the MQT data for realistic experimental parameters.

Many electrical grid transients can be described by the propagation of electromechanical (EM) waves that couple oscillations of power flows over transmission lines and the inertia of synchronous generators. These EM waves can take several forms: large-scale standing waves forming inter-area modes, localized oscillations of single or multi-machine modes, or traveling waves that spread quasi-circularly from major grid disturbances. The propagation speed and damping of these EM waves are potentially a powerful tool for assessing grid stability, e.g. small signal or rotor angle stability, however, EM wave properties have been mostly extracted from post-event analysis of major grid disturbances. Using a small set of data from the FNET sensor network, we show how the spatially resolved Green's function for EM wave propagation can be extracted from ambient frequency noise without the need for a major disturbance. If applied to an entire interconnection, an EM-wave Green's function map will enable a model-independent method of predicting the propagation of grid disturbances and assessing stability.

Noise is generally thought as detrimental for energy transport in coupled oscillator networks. However, it has been shown that for certain coherently evolving systems, the presence of noise can enhance, somehow unexpectedly, their transport efficiency; a phenomenon called environment-assisted quantum transport (ENAQT) or dephasing-assisted transport. Here, we report on the experimental observation of such effect in a network of coupled electrical oscillators. We demonstrate that by introducing stochastic fluctuations in one of the couplings of the network, a relative enhancement in the energy transport efficiency of $22.5 \pm 3.6\,\%$ can be observed.

The electrical noise signals generated in the individual conductors of coaxial and other cables by incident nuclear radiation pulses were studied as a function of the applied voltage and the exposure history. Training processes were found to reduce the response signals in repetitive exposures, while storage or memory effects can cause strong readout signals if the applied voltage is changed in successive shots. Oscillatory signals in the center conductor were found to be caused by differentiation of the unexpectedly large shield current pulses. The latter can also inject parasitic leakage currents into other conductors nearby. An RF signal transmitted through RG62 A/U cable suffers a temporary attenuation of almost 20%, while it passes through RG59 B/U cable unaffected. Methods for the dynamic meas urement of noise, resistance, attenuation and impedance are described, and definite rules are given for minimizing noise signals from cables used in nuclear pulse radiation measurements.

The objective of this program is to investigate the mechanisms of electrical conduction in amorphous silicon and identify factors affecting the performance of uncooled imaging focal plane array systems based on amorphous silicon microbolometer thermal detector structures. Measurements of the temperature dependence of conductivity and noise show that the dominant conduction mechanism in p-type a-Si:H is that of Mott variable range hopping. The hopping parameters are controlled by the film deposition conditions such as hydrogen dilution of the silane precursor and boron dopant level. The low frequency noise has a weak temperature dependence and is dominated by a 1/f component which follows the Hooge model and is correlated to the conductivity hopping parameters and in turn to the temperature coefficient of resistance (TCR).

Electrical noise and cross talk generated during explosive testing by gage and cable destruction were investigated. Results indicate that the primary instrumentation parameters affecting noise and cross talk levels are cable type, transducer bridge symmetry and its effects on signal conditioner common mode rejection ratio, and the degree of isolation between conditioner power circuits.

Electrical noise and cross talk generated during explosive testing by gage and cable destruction were investigated. Results indicate that the primary instrumentation parameters affecting noise and cross talk levels are cable type, transducer bridge symmetry and its effects on signal conditioner common mode rejection ratio, and the degree of isolation between conditioner power circuits.

We have studied temperature-dependent (77-300 K) electrical characteristics and low-frequency noise (LFN) in chemical vapor deposited (CVD) single-layer molybdenum disulfide (MoS2) based back-gated field-effect transistors (FETs). Electrical characterization and LFN measurements were conducted on MoS2 FETs with Al2O3 top-surface passivation. We also studied the effect of top-surface passivation etching on the electrical characteristics of the device. Significant decrease in channel current and transconductance was observed in these devices after the Al2O3 passivation etching. For passivated devices, the two-terminal resistance variation with temperature showed a good fit to the activation energy model, whereas for the etched devices the trend indicated a hopping transport mechanism. A significant increase in the normalized drain current noise power spectral density (PSD) was observed after the etching of the top passivation layer. The observed channel current noise was explained using a standard unified model incorporating carrier number fluctuation and correlated surface mobility fluctuation mechanisms. Detailed analysis of the gate-referred noise voltage PSD indicated the presence of different trapping states in passivated devices when compared to the etched devices. Etched devices showed weak temperature dependence of the channel current noise, whereas passivated devices exhibited near-linear temperature dependence.

Gap-junctional coupling is an important way of communication between neurons and other excitable cells. Strong electrical coupling synchronizes activity across cell ensembles. Surprisingly, in the presence of noise synchronous oscillations generated by an electrically coupled network may differ qualitatively from the oscillations produced by uncoupled individual cells forming the network. A prominent example of such behavior is the synchronized bursting in islets of Langerhans formed by pancreatic \beta-cells, which in isolation are known to exhibit irregular spiking. At the heart of this intriguing phenomenon lies denoising, a remarkable ability of electrical coupling to diminish the effects of noise acting on individual cells. In this paper, we derive quantitative estimates characterizing denoising in electrically coupled networks of conductance-based models of square wave bursting cells. Our analysis reveals the interplay of the intrinsic properties of the individual cells and network topology and their respective contributions to this important effect. In particular, we show that networks on graphs with large algebraic connectivity or small total effective resistance are better equipped for implementing denoising. As a by-product of the analysis of denoising, we analytically estimate the rate with which trajectories converge to the synchronization subspace and the stability of the latter to random perturbations. These estimates reveal the role of the network topology in synchronization. The analysis is complemented by numerical simulations of electrically coupled conductance-based networks. Taken together, these results explain the mechanisms underlying synchronization and denoising in an important class of biological models.

Electrical noise and cross talk generated during explosive testing by gage and cable destruction were investigated. Results indicate that the primary instrumentation parameters affecting noise and cross talk levels are cable type, transducer bridge symmetry and its effects on signal conditioner common mode rejection ratio, and the degree of isolation between conditioner power circuits.

This volume gives the assembly, adjustment, and checkout procedures necessary to construct a U.S. Army Construction Engineering Research Laboratory (CERL) True-Integrating Environmental Noise Monitor and Sound-Exposure Level Meter. It describes the monitor's mechanical layout, wiring guidelines, adjustments to components to bring various circuits into tolerance, and steps for verifying the correct operation of the monitor. Also included are test programs to be executed by the internal microprocessor to exercise the internal circuit to help checkout or repair. (Author)

In order to promote public education and public safety, equal justice for all, a better informed citizenry, the rule of law, world trade and world peace, this legal document is hereby made available on a noncommercial basis, as it is the right of all humans to know and speak the laws that govern them. (For more information: 12 Tables of Code ) Name of Legally Binding Document: GB 19606-102: Noise limit value for household and similar electrical appliances Name of Standards Organization: Standardization Administration of China (SAC) LEGALLY BINDING DOCUMENT

Superparamagnetic tunnel junctions are nanostructures that auto-oscillate stochastically under the effect of thermal noise. Recent works showed that despite their stochasticity, such junctions possess a capability to synchronize to subthreshold voltage drives, in a way that can be enhanced or controlled by adding noise. In this work, we investigate a system composed of two electrically coupled junctions, connected in series to a periodic voltage source. We make use of numerical simulations and of an analytical model to demonstrate that both junctions can be phase-locked to the drive, in phase or in anti-phase. This synchronization phenomenon can be controlled by both thermal and electrical noises, although the two types of noises induce qualitatively different behaviors. Namely, thermal noise can stabilize a regime where one junction is phase-locked to the drive voltage while the other is blocked in one state. On the contrary, electrical noise causes the junctions to have highly correlated behaviors and thus cannot induce the latter. These results open the way for the design of superparamagnetic tunnel junctions that can perform computation through synchronization, and which harvest the largest part of their energy consumption from thermal noise.

Close up recording of a humming electrical substation transformer box. Recorded with ZOOM H5.

Using the Keldysh Green function technique, we calculate the finite-frequency correlator between the electrical current and the heat current flowing through a quantum dot connected to reservoirs. At equilibrium, we find that this quantity, called mixed noise, is linked to the thermoelectric ac-conductance by the fluctuation-dissipation theorem. Out-of-equilibrium, we discuss its spectrum and find evidence of the close relationship between the mixed noise and the thermopower. We study the spectral coherence and identify the conditions to have a strong correlation between the electrical and heat currents. The change in the spectral coherence due to the presence of a temperature gradient between the reservoirs is also highlighted.

Electrical noise and cross talk generated during explosive testing by gage and cable destruction were investigated. Results indicate that the primary instrumentation parameters affecting noise and cross talk levels are cable type, transducer bridge symmetry and its effects on signal conditioner common mode rejection ratio, and the degree of isolation between conditioner power circuits.

Measurements of the dc transport properties and the low-frequency conductivity noise in films of charge ordered Nd_0.5Ca_0.5MnO_3 grown on Si subtrate reveal the existence of a threshold field in the charge ordered regime beyond which strong non linear conduction sets in along with a large broad band conductivity noise. Threshold-dependent conduction disappears as T -> T_{CO}, the charge ordering temperature. This observation suggests that the charge ordered state gets depinned at the onset of the non-linear conduction.

Measurements of the dc transport properties and the low-frequency conductivity noise in films of charge ordered Nd_0.5Ca_0.5MnO_3 grown on Si subtrate reveal the existence of a threshold field in the charge ordered regime beyond which strong non linear conduction sets in along with a large broad band conductivity noise. Threshold-dependent conduction disappears as T -> T_{CO}, the charge ordering temperature. This observation suggests that the charge ordered state gets depinned at the onset of the non-linear conduction.

Improvement of existing pulsejet engines resulted in engines having (1) a 425-fps design speed with a maximum over 500 fps, (2) a design-speed life exceeding 41 hr, (3) a 444-g design-acceleration loading with a maximum over 575 g, and (4) a specific thrust of 2.23. An analysis indicated that a 25% greater thrust is possible with a ducted engine at a 550-fps tip speed. Acoustic coupling of 2 engines with proximate tailpipes reduced the fundamental-frequency noise level. Exhaust-shroud design requirements were established for shrouds which enhance acoustic coupling and which do not adversely affect static performance. Opposed-engine configurations further reduced the noise level and favorably affected performance. The inlet noise level was not reduced by acoustically coupling /4 ducts. A capacitance-type pressure pickup with a 1.25- mc carrier frequency and a 50-psi maximum was used with a high-impedance probe to determine engine-pressure variations. Average inlet-valve operating temperatures of 145 deg F may permit the use of strain gages as inlet-valve position indicators. Inlet-valve natural frequency and damping characteristics could not be determined with commercial vibration equipment. Studies of electrical analogies for engine analysis provided (1) a basic circuit demonstrating the analogous behavior of electrical circuits and pulsejet engines, (2) a relaxation oscillator providing repetitive analogy operations and simulating combustion, (3) an artificial electrical line simulating acoustic resonant characteristics, and (4) a determination of engine-tube resonant modes.

Cryogen-free low-temperature setups are becoming more prominent in experimental science due to their convenience and reliability, and concern about the increasing scarcity of helium as a natural resource. Despite not having any moving parts at the cold end, pulse tube cryocoolers introduce vibrations that can be detrimental to the experiments. We characterize the coupling of these vibrations to the electrical signal observed on cables installed in a cryogen-free dilution refrigerator. The dominant electrical noise is in the 5 to 10 kHz range and its magnitude is found to be strongly temperature dependent. We test the performance of different cables designed to diagnose and tackle the noise, and find triboelectrics to be the dominant mechanism coupling the vibrations to the electrical signal. Flattening a semi-rigid cable or jacketing a flexible cable in order to restrict movement within the cable, successfully reduces the noise level by over an order of magnitude. Furthermore, we characterize the effect of the pulse tube vibrations on an electron spin qubit device in this setup. Coherence measurements are used to map out the spectrum of the noise experienced by the qubit, revealing spectral components matching the spectral signature of the pulse tube.

A short review is presented of a recently developed computational approach which allows the study of the resistance noise over the full range of bias values, from the linear regime up to electrical breakdown. Resistance noise is described in terms of two competing processes in a random resistor network. The two processes are thermally activated and driven by an electrical bias. In the linear regime, a scaling relation has been found between the relative variance of resistance fluctuations and the average resistance. The value of the critical exponent is significantly higher than that associated with 1/f noise. In the nonlinear regime, occurring when the bias overcomes the threshold value, the relative variance of resistance fluctuations scales with the bias. Two regions can be identified in this regime: a moderate bias region and a pre-breakdown one. In the first region, the scaling exponent has been found independent of the values of the model parameters and of the bias conditions. A strong nonlinearity emerges in the pre-breakdown region which is also characterized by non-Gaussian noise. The results compare well with measurements of electrical breakdown in composites and with electromigration experiments in metallic lines.

We investigate the spin entanglement in the superconductor-quantum dot system proposed by Recher, Sukhorukov and Loss, coupling it to an electronic beam-splitter. The superconductor-quantum dot entangler and the beam-splitter are treated within a unified framework and the entanglement is detected via current correlations. The state emitted by the entangler is found to be a linear superposition of non-local spin-singlets at different energies, a spin-entangled two-particle wavepacket. Colliding the two electrons in the beam-splitter, the singlet spin-state gives rise to a bunching behavior, detectable via the current correlators. The amount of bunching depends on the relative positions of the single particle levels in the quantum dots and the scattering amplitudes of the beam-splitter. The singlet spin entanglement, insensitive to orbital dephasing but suppressed by spin dephasing, is conveniently quantified via the Fano factors. It is found that the entanglement-dependent contribution to the Fano factor is of the same magnitude as the non-entangled, making an experimental detection feasible. A detailed comparison between the current correlations of the non-local spin-singlet state and other states, possibly emitted by the entangler, is performed. This provides conditions for an unambiguous identification of the non-local singlet spin entanglement.

Virtually every device that makes use of the new ceramic superconductors will need normal conductor to superconductor contacts. The current-voltage and electrical noise characteristics of these contacts could become important design considerations. I-V and low frequency electrical noise measurements are presented on contacts between a normal conductor and superconducting polycrystalline YBa2Cu3O7. The contacts were formed by first sputtering gold palladium pads onto the surface of the bulk superconductor and then using silver epoxy to attach a wire(s) to each pad. Voltage across the contacts was found for small current densities. The voltage spectral density, S sub v(f), a quantity often used to characterize electrical noise, very closely followed an empirical relationship given by S sub v(f) = C(VR)sq/f, where V is the DC voltage across the contact, R is the contact resistance, F is frequency, and C is a contant found to be 2 x 10(exp -10)/Omega sq at 78 K. This relationship was found to be independent of contact area, contact geometry, sample fabrication technique, and sample density.

Since 1984, electric cell-substrate impedance sensing (ECIS) has been used to monitor cell behavior in tissue culture and has proven sensitive to cell morphological changes and cell motility. We have taken ECIS measurements on several cultures of non-cancerous (HOSE) and cancerous (SKOV) human ovarian surface epithelial cells. By analyzing the noise in real and imaginary electrical impedance, we demonstrate that it is possible to distinguish the two cell types purely from signatures of their electrical noise. Our measures include power-spectral exponents, Hurst and detrended fluctuation analysis, and estimates of correlation time; principal-component analysis combines all the measures. The noise from both cancerous and non-cancerous cultures shows correlations on many time scales, but these correlations are stronger for the non-cancerous cells.

We investigate the influence of electrical charge noise on a resonant exchange (RX) qubit in a triple quantum dot. This RX qubit is a variation of the exchange-only spin qubit which responds to a narrow-band resonant frequency. Our noise model includes uncorrelated charge noise in each quantum dot giving rise to two independent (noisy) bias parameters $\varepsilon$ and $\Delta$. We calculate the energy splitting of the two qubit states as a function of these two bias detuning parameters to find "sweet spots", where the qubit is least susceptible to noise. Our investigation shows that such sweet spots exist within the low bias regime, in which the bias detuning parameters have the same magnitude as the hopping parameters. The location of the sweet spots in the $(\varepsilon,\Delta)$ plane depends on the hopping strength and asymmetry between the quantum dots. In the regime of weak charge noise, we identify a new favorable operating regime for the RX qubit based on these sweet spots.