Search results for "electronics"

Noise Induced Phenomena in point Josephson junctions

2008

We present the analysis of the mean switching time and its standard deviation of short overdamped Josephson junctions, driven by a direct current and a periodic signal. The effect of noise enhanced stability is investigated. It is shown that fluctuations may both decrease and increase the switching time.

Dephasing due to quasiparticle tunneling in fluxonium qubits: a phenomenological approach

2015

The fluxonium qubit has arisen as one of the most promising candidate devices for implementing quantum information in superconducting devices, since it is both insensitive to charge noise (like flux qubits) and insensitive to flux noise (like charge qubits). Here, we investigate the stability of the quantum information to quasiparticle tunneling through a Josephson junction. Microscopically, this dephasing is due to the dependence of the quasiparticle transmission probability on the qubit state. We argue that on a phenomenological level the dephasing mechanism can be understood as originating from heat currents, which are flowing in the device due to possible effective temperature gradients…

2012

classical and quantum systems are investigated. First, the role of multiplicative and additive noise in a classical metastable system is analyzed. The mean lifetime of the metastable state shows a nonmonotonic behavior with a maximum as a function of both the additive and multiplicative noise intensities. In the second system, the simultaneous action of thermal and non-Gaussian noise on the dynamics of an overdamped point Josephson junction is studied. The eect of a Levy noise generated by a Cauchy‐Lorentz distribution on the mean lifetime of the superconductive metastable state, in the presence of a periodic driving, is investigated. We find resonant activation and noise enhanced stability…

Noise stabilization effects in models of interdisciplinary physics

2009

Metastability is a generic feature of many nonlinear systems, and the problem of the lifetime of metastable states involves fundamental aspects of nonequilibrium statistical mechanics. The investigation of noise-induced phenomena in far from equilibrium systems is one of the approaches used to understand the behaviour of physical and biological complex systems. The enhancement of the lifetime of metastable states through the noise enhanced stability effect and the role played by the resonant activation phenomenon will be discussed in models of interdisciplinary physics: (i) polymer translocation dynamics; (ii) transient regime of FitzHugh-Nagumo model; (iii) market stability in a nonlinear …

Self-assembly of Organic Molecules on Insulating Surfaces

2015

Molecular self-assembly is known to provide a powerful tool for creating functional structures, with the ultimate structure and functionality encoded in the molecular building blocks. Upon molecule deposition onto surfaces, functional structures have been created ranging from defect-free, highly symmetric two-dimensional layers to complex assemblies with dedicated functionality. Especially organic molecules play a key role for molecular self-assembly due to their impressive structural flexibility and the high degree of control by chemical synthesis. Furthermore, the surface itself provides another exciting dimension: adjusting the subtle balance between intermolecular and molecule-surface i…

Structural characterization of selective area growth GaN nanowires by non-destructive optical and electrical techniques

2015

The growth selectivity and structural quality of GaN nanowires obtained by plasma-assisted molecular beam epitaxy on pre-patterned GaN(0001) templates are investigated by means of non-destructive techniques. Optimum control over the nanowire arrangement and size requires a pitch between the mask apertures below twice the diffusion length of Ga atoms. Lower pitches, however, seem to slightly diminish the structural quality of the material, as revealed by the increase of the Raman peak linewidths. The photoluminescence spectra of the nanowires show a considerable presence of basal plane stacking faults, whose density increases for decreasing nanowire diameter. The capabilities of Kelvin probe…

Integrated Optical Technique for Detection of Electro-Optical Non-Linearities in Thin Films

1976

A simple method for detection of electro-optical non-linearities in thin films is presented. The method involves an easily fabricated structure and a little practice in integrated optical techniques. It is also possible to detect small induced variations of refractive index, using lower voltage with respect to those applied in a conventional Kerr cell. We have sucessfully tested our method using two different polymer materials as thin films. In both of these we have observed an induced ?n ? 3 10?5 with an electric field of 60 V/?, with a response time round about 300 nsec. The experimental values of induced ?n versus electric field fit very well a parabola, proving the quadratic behavior of…

Formation Kinetics of Mixed Self-Assembled Monolayers of Alkanethiols on GaAs(100)

2017

International audience; We report on the formation kinetics of mixed self-assembled monolayers (SAMs) comprising 16-mercaptohexadecanoic acid (MHDA) and 11-mercapto-1-undecanol (MUDO) thiols on GaAs(100) substrates. These compounds were selected for their potential in constructing highly selective and efficient architectures for biosensing applications. The molecular composition and quality of one-compound and mixed SAMs were determined by the Fourier transform infrared absorption spectroscopy measurements. The formation of enhanced-quality mixed SAMs was investigated as a function of the molecular composition of the thiol mixture and the proportion of ethanol/water solvent used during thei…

Co-occurrence of resonant activation and noise-enhanced stability in a model of cancer growth in the presence of immune response.

2006

We investigate a stochastic version of a simple enzymatic reaction which follows the generic Michaelis-Menten kinetics. At sufficiently high concentrations of reacting species, the molecular fluctuations can be approximated as a realization of a Brownian dynamics for which the model reaction kinetics takes on the form of a stochastic differential equation. After eliminating a fast kinetics, the model can be rephrased into a form of a one-dimensional overdamped Langevin equation. We discuss physical aspects of environmental noises acting in such a reduced system, pointing out the possibility of coexistence of dynamical regimes where noise-enhanced stability and resonant activation phenomena …

Oxidation of niobium sheets at high temperature

1997

Abstract This work shows the role of oxygen pressure on growth kinetics, morphology, phase composition and texture of oxide scale in the oxidation of niobium sheets at 900 °C. The particular morphology observed at low pressure shows the existence of competition between edge and surface growth mechanisms. Pressure and conversion rate influence the nature of preferential orientations of the Nb2O5 oxide layer: a [110] fibre axis is stabilized at high pressure but, at low pressure, the higher is the conversion rate, the more evident is this fibre axis. This behaviour is observed not only after cooling but also in situ. At high pressure, the evolution is not only temporal but also spatial: with …