Quantum chaos in the mesoscopic device for the Josephson flux qubit

We show that the three-junction SQUID device designed for the Josephson flux qubit can be used to study quantum chaos when operated at high energies. In the parameter region where the system is classically chaotic we analyze the spectral statistics. The nearest neighbor distributions $P(s)$ are well fitted by the Berry Robnik theory employing as free parameters the pure classical measures of the chaotic and regular regions of phase space in the different energy regions. The phase space representation of the wave functions is obtained via the Husimi distributions and the localization of the states on classical structures is analyzed.Comment: Final version, to be published in Phys. Rev. B. References added, introduction and conclusions improve

Testing general relativity using golden black-hole binaries

The coalescences of stellar-mass black-hole binaries through their inspiral, merger, and ringdown are among the most promising sources for ground-based gravitational-wave (GW) detectors. If a GW signal is observed with sufficient signal-to-noise ratio, the masses and spins of the black holes can be estimated from just the inspiral part of the signal. Using these estimates of the initial parameters of the binary, the mass and spin of the final black hole can be uniquely predicted making use of general-relativistic numerical simulations. In addition, the mass and spin of the final black hole can be independently estimated from the merger--ringdown part of the signal. If the binary black hole dynamics is correctly described by general relativity (GR), these independent estimates have to be consistent with each other. We present a Bayesian implementation of such a test of general relativity, which allows us to combine the constraints from multiple observations. Using kludge modified GR waveforms, we demonstrate that this test can detect sufficiently large deviations from GR, and outline the expected constraints from upcoming GW observations using the second-generation of ground-based GW detectors.Comment: 5 pages, 2 fig

Simultaneous XMM-Newton and ESO VLT observations of SN 1995N: probing the wind/ejecta interaction

We present the results of the first {\it XMM-Newton} observation of the interacting type IIn supernova 1995N, performed in July 2003. We find that the 0.2--10.0 keV unabsorbed flux dropped at a value of $\simeq 1.8 \times 10^{-13}$ erg cm$^{-2}$ s$^{-1}$, almost one order of magnitude lower than that of a previous {\it ASCA} observation of January 1998. From all the available X-ray measurements, an interesting scenario emerges where the X-ray light emission may be produced by a two-phase (clumpy/smooth) circumstellar medium. The X-ray spectral analysis shows statistically significant evidence for the presence of two distinct components, that can be modeled with emission from optically thin, thermal plasmas at different temperatures. The exponent of the ejecta density distribution inferred from these temperatures is $n\simeq 6.4$. From the fluxes of the two spectral components we derive an estimate of the mass loss rate of the supernova progenitor, ${\dot M} \sim 2 \times 10^{-4} M_\odot {\rm yr}^{-1}$, at the upper end of the interval exhibited by red super-giants. Coordinated optical and infrared observations allow us to reconstruct the simultaneous infrared to X-ray flux distribution of SN 1995N. We find that, at $\sim$ 9 years after explosion, the direct X-ray thermal emission due to the wind/ejecta interaction is $\sim 5$ times larger than the total reprocessed IR/optical flux.Comment: 11 pages, 7 figures, MNRAS, in pres

Micelles by self-assembling peptide-conjugate amphiphile: synthesis and structural characterization.

The solid-phase synthesis of a novel amphiphilic peptide conjugate I, contg. in the same mol. three different functions: N,N-bis[2-[bis(carboxyethyl)amino]ethyl]-L-glutamic acid chelating agent, the CCK8 bioactive peptide, and a hydrophobic moiety contg. four alkyl chains with 18 carbon atoms each, is reported. In water soln. at pH 7.4, I self-assembles in very stable micelles at very low concn. [crit. micellar concn. (cmc) values of 5 10-7 mol kg-1] as confirmed by fluorescence spectroscopy. The structural characterization, obtained with small-angle neutron scattering (SANS) measurements, indicates that the aggregates are substantially represented by ellipsoidal micelles with an aggregation no. of 39 2 and the two micellar axes of about 52 and 26

Structure of nanoparticles embedded in micellar polycrystals

We investigate by scattering techniques the structure of water-based soft composite materials comprising a crystal made of Pluronic block-copolymer micelles arranged in a face-centered cubic lattice and a small amount (at most 2% by volume) of silica nanoparticles, of size comparable to that of the micelles. The copolymer is thermosensitive: it is hydrophilic and fully dissolved in water at low temperature (T ~ 0{\deg}C), and self-assembles into micelles at room temperature, where the block-copolymer is amphiphilic. We use contrast matching small-angle neuron scattering experiments to probe independently the structure of the nanoparticles and that of the polymer. We find that the nanoparticles do not perturb the crystalline order. In addition, a structure peak is measured for the silica nanoparticles dispersed in the polycrystalline samples. This implies that the samples are spatially heterogeneous and comprise, without macroscopic phase separation, silica-poor and silica-rich regions. We show that the nanoparticle concentration in the silica-rich regions is about tenfold the average concentration. These regions are grain boundaries between crystallites, where nanoparticles concentrate, as shown by static light scattering and by light microscopy imaging of the samples. We show that the temperature rate at which the sample is prepared strongly influence the segregation of the nanoparticles in the grain-boundaries.Comment: accepted for publication in Langmui

Spitzer measurements of atomic and molecular abundances in the Type IIP SN 2005af

We present results based on Spitzer Space Telescope mid-infrared (3.6-30 micron) observations of the nearby IIP supernova 2005af. We report the first ever detection of the SiO molecule in a Type IIP supernova. Together with the detection of the CO fundamental, this is an exciting finding as it may signal the onset of dust condensation in the ejecta. From a wealth of fine-structure lines we provide abundance estimates for stable Ni, Ar, and Ne which, via spectral synthesis, may be used to constrain nucleosynthesis models.Comment: ApJ Letters (accepted

Triple Michelson Interferometer for a Third-Generation Gravitational Wave Detector

The upcoming European design study `Einstein gravitational-wave Telescope' represents the first step towards a substantial, international effort for the design of a third-generation interferometric gravitational wave detector. It is generally believed that third-generation instruments might not be installed into existing infrastructures but will provoke a new search for optimal detector sites. Consequently, the detector design could be subject to fewer constraints than the on-going design of the second generation instruments. In particular, it will be prudent to investigate alternatives to the traditional L-shaped Michelson interferometer. In this article, we review an old proposal to use three Michelson interferometers in a triangular configuration. We use this example of a triple Michelson interferometer to clarify the terminology and will put this idea into the context of more recent research on interferometer technologies. Furthermore the benefits of a triangular detector will be used to motivate this design as a good starting point for a more detailed research effort towards a third-generation gravitational wave detector.Comment: Minor corrections to the main text and two additional appendices. 14 pages, 6 figure

A Spitzer Space Telescope study of SN 2002hh: an infrared echo from a Type IIP supernova

We present late-time (590-994 d) mid-IR photometry of the normal, but highly-reddened Type IIP supernova SN 2002hh. Bright, cool, slowly-fading emission is detected from the direction of the supernova. Most of this flux appears not to be driven by the supernova event but instead probably originates in a cool, obscured star-formation region or molecular cloud along the line-of-sight. We also show, however, that the declining component of the flux is consistent with an SN-powered IR echo from a dusty progenitor CSM. Mid-IR emission could also be coming from newly-condensed dust and/or an ejecta/CSM impact but their contributions are likely to be small. For the case of a CSM-IR echo, we infer a dust mass of as little as 0.036 M(solar) with a corresponding CSM mass of 3.6(0.01/r(dg))M(solar) where r(dg) is the dust-to-gas mass ratio. Such a CSM would have resulted from episodic mass loss whose rate declined significantly about 28,000 years ago. Alternatively, an IR echo from a surrounding, dense, dusty molecular cloud might also have been responsible for the fading component. Either way, this is the first time that an IR echo has been clearly identified in a Type IIP supernova. We find no evidence for or against the proposal that Type IIP supernovae produce large amounts of dust via grain condensation in the ejecta. However, within the CSM-IR echo scenario, the mass of dust derived implies that the progenitors of the most common of core-collapse supernovae may make an important contribution to the universal dust content.Comment: 41 pages, 11 figures, 4 tables, accepted for publication in Astrophysical Journal (References corrected

Huge Electro-/photo-/acidoinduced Second-order Nonlinear Contrasts from Multiaddressable Indolinooxazolodine

In this work, linear and nonlinear optical properties of electro-/acido-/photoswitchable indolino[2,1-b]oxazolidine derivatives were investigated. The linear optical properties of the closed and open forms have been characterized by UV–visible and IR spectroscopies associated with DFT calculations. Nonlinear optical properties of the compounds have been obtained by ex situ and in situ hyper-Rayleigh experiments in solution. We show that protonated, oxidized, and irradiated open forms exhibit the same visible absorption and NLO features. In particular, the closed and open forms exhibit a huge contrast of the first hyperpolarizability with an enhancement factor of 40–45. Additionally, we have designed an original electrochemical cell that allows to monitor in situ the hyper-Rayleigh response upon electrical stimulus. We report notably a partial but good and reversible NLO contrast in situ during oxidation/reduction cycles. Thereby, indolinooxazolidine moieties are versatile trimodal switchable units which are very promising for applications in devices