81 research outputs found
Shear and longitudinal viscosity of non-ionic C12E8 aqueous solutions
We present measurements of the steady shear viscosity, the longitudinal
elastic modulus and the ultrasonic absorption in the one-phase isotropic liquid
region of the nonionic surfactant C12E8 aqueous solutions. The overall results
support the presence of two separated intervals of concentration corresponding
to different structural properties. In the surfactant-rich region the
temperature dependence of the steady shear viscosity follows an equation
characteristic of glass-like systems. The ultrasonic absorption spectra show
unambiguous evidence of viscoelastic behaviour described by a Cole-Cole
relaxation formula. In the water-rich region the behaviour of the measured
quantities are more complex and reflect the presence of dispersed aggregates
whose size increases with temperature and concentration. An additional low
frequency contribution is also observed, which is ascribed to the exchange of
water molecules and/or surfactant monomers between the aggregates and the bulk
solvent region.Comment: 23 Pages, 7 Figures, 1 Table, submitted to J. Phys. Chem B, accepted
for publicatio
Spin-echo entanglement protection from random telegraph noise
We analyze local spin-echo procedures to protect entanglement between two
non-interacting qubits, each subject to pure-dephasing random telegraph noise.
For superconducting qubits this simple model captures characteristic features
of the effect of bistable impurities coupled to the device. An analytic
expression for the entanglement dynamics is reported. Peculiar features related
to the non-Gaussian nature of the noise already observed in the single qubit
dynamics also occur in the entanglement dynamics for proper values of the ratio
, between the qubit-impurity coupling strength and the switching
rate of the random telegraph process, and of the separation between the pulses
. We find that the echo procedure may delay the disappearance of
entanglement, cancel the dynamical structure of entanglement revivals and dark
periods, and induce peculiar plateau-like behaviors of the concurrence.Comment: 9 pages, 2 figure
Memory effects in a Markov chain dephasing channel
We study a dephasing channel with memory, modelled by a Markov chain. We show
that even weak memory effects have a detrimental impact on the performance of
quantum error correcting schemes designed for uncorrelated errors. We also
discuss an alternative scheme that takes advantage of memory effects to protect
quantum information.Comment: 5 pages, 1 figure, NIC@QS proceeding
Open-loop quantum control of small-size networks for high-order cumulants and cross-correlations sensing
Quantum control techniques represent one of the most efficient tools to
attain high-fidelity quantum operations and a convenient approach for quantum
sensing and quantum noise spectroscopy. In this work, we investigate dynamical
decoupling while processing an entangling two-qubit gate based on an Ising-xx
interaction, each qubit being affected by pure dephasing classical correlated
1/ f -noises. To evaluate the gate error, we used the Magnus expansion
introducing generalized filter functions that describe decoupling while
processing and allow us to derive an approximate analytic expression as a
hierarchy of nested integrals of noise cumulants. The error is separated in
contributions of Gaussian and non-Gaussian noise, the corresponding generalized
filter functions being calculated up to the fourth order. By exploiting the
properties of selected pulse sequences, we show that it is possible to extract
the second-order statistics (spectrum and cross-spectrum) and to highlight
non-Gaussian features contained in the fourth-order cumulant. We discuss the
applicability of these results to state-of-the-art small networks based on
solid-state platforms.Comment: 19 pages, 7 figure
Decay of nonlocality due to adiabatic and quantum noise in the solid state
We study the decay of quantum nonlocality, identified by the violation of the Clauser-Horne-Shimony-Holt (CHSH) Bell inequality, for two noninteracting Josephson qubits subject to independent baths with broadband spectra typical of solid state nanodevices. The bath noise can be separated in an adiabatic (low-frequency) and in a quantum (high-frequency) part. We point out the qualitative different effects on quantum nonlocal correlations induced by adiabatic and quantum noise. A quantitative analysis is performed for typical noise figures in Josephson systems. Finally we compare, for this system, the dynamics of nonlocal correlations and of entanglement
Essential Oils of Dennettia Tripetala Bak. f. Stem Bark and Leaf – Constituents and Biological Activities:
The essential oil from the stem bark and leaves of Dennettia tripetala Bak. f. (Annonaceae) growing wild in Ondo State, Nigeria, has been characterized by combined gas chromatography (GC) and gas chromatography-mass spectrometry (GC- MS) analyses. Overall, thirty-six components have been fully identified, thirty-two in the stem-bark oil, and only seven in the leaf oil. In both oils, 2-phenylnitroethane was the main component, ranging between 70 – 76% of the total oils. The profile of the stem bark oil was characterized by a large number of sesquiterpenes, whereas among the few components in the leaf oil, linalool reaches over 17%. When both oils were assayed for antimicrobial activity, only Staphylococcus aureus was susceptible to the stem-bark oil which was more active than leaf oil. For protective effects against UV radiation–induced peroxidation in phosphatidylcholine (PC) liposomes, stem-bark oil also showed greater effectiveness. Activity of the leaf oil against Trichomonas gallinae, was also remarkable
Large area SiC-UV phothodiode for spectroscopy portable system
In this work, we present the extensive characterization of large area Silicon Carbide based UV sensors candidate for outdoors spectroscopic applications of gas or liquid. The proposed SiC Schottky devices exhibit dark current density of 0.12 nA/cm2 @ 15 V, a 0.12 A/W responsivity @ 300 nm, optimal visible blindness and switching time of ~ 190 ns. Effects of temperature on the sensor performance, of crucial interest for outdoors applications, are also examined in the range from -20 °C to 90 °C.Published2931 - 29367TM. Sviluppo e Trasferimento TecnologicoJCR Journa
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