共查询到20条相似文献,搜索用时 15 毫秒
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R. D. S. Yadava 《Zeitschrift für Physik B Condensed Matter》1989,76(3):365-374
The problem of 1/f noise in thin metal films and metal-insulator composites in the scaling fractal regime near percolation threshold is considered. The correspondence between a percolation transition and a second order phase transition is extended from the point of view of electronic polarization and electrical fluctuations. The charge fluctuations on finite fractal clusters are argued to be analogous to spontaneous order parameter fluctuations in phase transitions, being correlated upto percolation correlation length. The charge relaxation times are shown to be related to the cluster sizes having distribution function of the formg()–b
, whereb is connected to Euclidean and fractal dimensionalities and critical exponents. This produces the 1/f noise spectrum. Below percolation threshold, the nodes-links-blobs picture is invoked such that the blobs represent metallic conductances of the finite clusters and the links are tunnelling conductances between them through narrowest barrier regions. Above threshold, the finite cluster network is visualized as connected to the infinite cluster through narrowest tunnelling regions. The correlated spontaneous charge fluctuation on finite fractal clusters is held responsible for conductance fluctuation on either side of the metal-insulator transition via tunnelling processes. Finally, the scaling behaviour of noise magnitude near percolation threshold is explained. 相似文献
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A. G. Golovko 《Russian Physics Journal》1980,23(11):920-923
An experimental investigation was made of low-frequency fluctuations of the open-circuit voltage of mass-produced Varistors made of silicon carbide. It was concluded that the main charge transport mechanism in varistors may be the Frenkel ionization of impurities.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 11–15, November, 1980. 相似文献
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A. G. Golovko 《Radiophysics and Quantum Electronics》1978,21(10):1065-1068
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Arthur R. Butz 《Journal of statistical physics》1972,4(2-3):199-216
Letu() be an absolutely integrable function and define the random process where thet
i are Poisson arrivals and thes
i, are identically distributed nonnegative random variables. Under routine independence assumptions, one may then calculate a formula for the spectrum ofn(t), S
n(), in terms of the probability density ofs, ps(). If any probability density ps() having the property ps() I for small is substituted into this formula, the calculated Sn() is such that Sn() 1 for small . However, this is not a spectrum of a well-defined random process; here, it is termed alimit spectrum. If a probability density having the property ps()
for small , where > 0, is substituted into the formula instead, a spectrum is calculated which is indeed the spectrum of a well-defined random process. Also, if the latter ps is suitably close to the former ps, then the spectrum in the second case approximates, to an arbitrary, degree of accuracy, the limit spectrum. It is shown how one may thereby have 1/f noise with low-frequency turnover, and also strict 1/f
1– noise (the latter spectrum being integrable for > 0). Suitable examples are given. Actually, u() may be itself a random process, and the theory is developed on this basis. 相似文献
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A sinusoidal ac current of frequeencyf c generates an excess noise in many solidstate conductors. The power spectrum of this noise is calculated starting from the autocorrelation function of the stochastic process. Besides a 1/Δf term the spectrum includes another contribution varying with 1/(f c+f). In the low frequency range there is white noise. 相似文献
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It is shown that the energy spectrum fluctuations of quantum systems can be formally considered as a discrete time series. The power spectrum behavior of such a signal for different systems suggests the following conjecture: The energy spectra of chaotic quantum systems are characterized by 1/f noise. 相似文献
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The generation of 1/f noise is demonstrated experimentally in a system consisting of a superconducting film carrying a transport current in contact
with a boiling liquid coolant. It is found that wide-band 1/f noise with a large amplitude of the fluctuations is observed over a wide range of parameters. This noise is attributed to
the fact that the sub-systems in contact have the same character of the relaxational dependences δT(t)∼ t
−1/2.
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 9, 739–742 (10 May 1996) 相似文献
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We propose and study a model of dephasing due to an environment of bistable fluctuators. We apply our analysis to the decoherence of Josephson qubits, induced by background charges present in the substrate, which are also responsible for the 1/f noise. The discrete nature of the environment leads to a number of new features which are mostly pronounced for slowly moving charges. Far away from the degeneracy this model for the dephasing is solved exactly. 相似文献
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The $1/f$ noise in multiwalled carbon nanotubes bundles has been investigated between the frequency range of 0.1 to 30 Hz. At room temperature the noise spectrum is standard 1/f, and its level is proportional to the square of the bias voltage. With decreasing temperature the noise level also decreases. At 4.2 K the noise level follows a non-monotonic dependence against the bias voltage, showing a peak at a certain bias voltage, meanwhile its frequency dependence also deviates from the 1/f trend. This anomalous behaviour is discussed within the picture of environmental quantum fluctuation of charge transport in the samples. 相似文献
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Bialczak RC McDermott R Ansmann M Hofheinz M Katz N Lucero E Neeley M O'Connell AD Wang H Cleland AN Martinis JM 《Physical review letters》2007,99(18):187006
We present a new method to measure 1/f noise in Josephson quantum bits (qubits) that yields low-frequency spectra below 1 Hz. A comparison of the noise taken at positive and negative bias of a phase qubit shows the dominant noise source to be flux noise and not junction critical-current noise, with a magnitude similar to that measured previously in other systems. Theoretical calculations show that the level of flux noise is not compatible with the standard model of noise from two-level state defects in the surface oxides of the films. 相似文献
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Yu. E. Kuzovlev 《Journal of Experimental and Theoretical Physics》1997,84(6):1138-1144
This paper examines the relationships that exist between low-frequency fluctuations of the rate of dissipation in nonequilibrium
thermodynamic systems and higher-order multitime statistical moments of equilibrium noise. In particular, it studies the relationships
between internal friction fluctuations in the phonon system being excited and low-frequency fluctuations of Raman scattering
of light in an equilibrium phonon system. We show that both processes are related to strong fluctuations in the phase diffusion
rate and the relaxation of phonon modes generated, in turn, by the exponential instability of the dynamical paths of the system.
Zh. éksp. Teor. Fiz. 111, 2086–2098 (June 1997) 相似文献
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Recently we have shown that slow relaxations in the electron glass system can be understood in terms of the spectrum of a matrix describing the relaxation of the system close to a metastable state. The model focused on the electron glass system, but its generality was demonstrated on various other examples. Here, we study the noise spectrum in the same framework. We obtain a remarkable relation between the spectrum of relaxation rates λ described by the distribution function P (λ) ~ 1/λ and the 1/f noise in the fluctuating occupancies of the localized electronic sites. This noise can be observed using local capacitance measurements. We confirm our analytic results using numerics, and also show how the Onsager symmetry is fulfilled in the system. 相似文献