The application of semiconductors to quasi- optical isolators for use at submillimeter wavelengths

Semiconductor application to quasi-optical isolators - nonreciprocal reflection beam isolator and far infrared isolators using Faraday rotatio

Rank/select queries over mutable bitmaps

The problem of answering rank/select queries over a bitmap is of utmost importance for many succinct data structures. When the bitmap does not change, many solutions exist in the theoretical and practical side. In this work we consider the case where one is allowed to modify the bitmap via a flip(i) operation that toggles its ith bit. By adapting and properly extending some results concerning prefix-sum data structures, we present a practical solution to the problem, tailored for modern CPU instruction sets. Compared to the state-of-the-art, our solution improves runtime with no space degradation. Moreover, it does not incur in a significant runtime penalty when compared to the fastest immutable indexes, while providing even lower space overhead. (C) 2021 Elsevier Ltd. All rights reserved

Role of dynamic Jahn-Teller distortions in Na2C60 and Na2CsC60 studied by NMR

Through 13C NMR spin lattice relaxation (T1) measurements in cubic Na2C60, we detect a gap in its electronic excitations, similar to that observed in tetragonal A4C60. This establishes that Jahn-Teller distortions (JTD) and strong electronic correlations must be considered to understand the behaviour of even electron systems, regardless of the structure. Furthermore, in metallic Na2CsC60, a similar contribution to T1 is also detected for 13C and 133Cs NMR, implying the occurence of excitations typical of JT distorted C60^{2-} (or equivalently C60^{4-}). This supports the idea that dynamic JTD can induce attractive electronic interactions in odd electron systems.Comment: 3 figure

Nonequilibrium steady states of driven magnetic flux lines in disordered type-II superconductors

We investigate driven magnetic flux lines in layered type-II superconductors subject to various configurations of strong point or columnar pinning centers by means of a three-dimensional elastic line model and Metropolis Monte Carlo simulations. We characterize the resulting nonequilibrium steady states by means of the force-velocity / current-voltage curve, static structure factor, mean vortex radius of gyration, number of double-kink and half-loop excitations, and velocity / voltage noise spectrum. We compare the results for the above observables for randomly distributed point and columnar defects, and demonstrate that the three-dimensional flux line structures and their fluctuations lead to a remarkable variety of complex phenomena in the steady-state transport properties of bulk superconductors.Comment: 23 pages, IOP style, 18 figures include

An Eccentric Eclipsing Binary: CGAur

In this study, we present CG Aur's photometric observations obtained in the observing seasons 2011 and 2012, the first available multi-colour light curves. Their shape indicates that the system is an Algol binary. The light curve analyses reveal that CG Aur is a detached binary system with an effective temperature difference between the components, approximately 1000 K. The first estimate of the absolute dimensions of the components indicated that the system locates on the main sequence in the HR diagram. The primary component is slightly evolved from the ZAMS.Comment: 18 pages, 6 figures, 3 table

High Field magnetospectroscopy to probe the 1.4eV Ni color center in diamond

A magneto-optical study of the 1.4 eV Ni color center in boron-free synthetic diamond, grown at high pressure and high temperature, has been performed in magnetic fields up to 56 T. The data is interpreted using the effective spin Hamiltonian of Nazar\'e, Nevers and Davies [Phys. Rev. B 43, 14196 (1991)] for interstitial Ni$^{+}$ with the electronic configuration $3d^{9}$ and effective spin $S=1/2$. Our results unequivocally demonstrate the trigonal symmetry of the defect which preferentially aligns along the [111] growth direction on the (111) face, but reveal the shortcomings of the crystal field model for this particular defect.Comment: 12 pages, 13 figures, submitted to PR

On Detection of Black Hole Quasi-Normal Ringdowns: Detection Efficiency and Waveform Parameter Determination in Matched Filtering

Gravitational radiation from a slightly distorted black hole with ringdown waveform is well understood in general relativity. It provides a probe for direct observation of black holes and determination of their physical parameters, masses and angular momenta (Kerr parameters). For ringdown searches using data of gravitational wave detectors, matched filtering technique is useful. In this paper, we describe studies on problems in matched filtering analysis in realistic gravitational wave searches using observational data. Above all, we focus on template constructions, matches or signal-to-noise ratios (SNRs), detection probabilities for Galactic events, and accuracies in evaluation of waveform parameters or black hole hairs. We have performed matched filtering analysis for artificial ringdown signals which are generated with Monte-Carlo technique and injected into the TAMA300 observational data. It is shown that with TAMA300 sensitivity, the detection probability for Galactic ringdown events is about 50% for black holes of masses greater than $20 M_{\odot}$ with SNR $> 10$. The accuracies in waveform parameter estimations are found to be consistent with the template spacings, and resolutions for black hole masses and the Kerr parameters are evaluated as a few % and $\sim 40$, respectively. They can be improved up to $< 0.9$ and $< 24$ for events of ${\rm SNR} \ge 10$ by using fine-meshed template bank in the hierarchical search strategy.Comment: 10 pages, 10 figure

Stochastic backgrounds of gravitational waves from extragalactic sources

Astrophysical sources emit gravitational waves in a large variety of processes occurred since the beginning of star and galaxy formation. These waves permeate our high redshift Universe, and form a background which is the result of the superposition of different components, each associated to a specific astrophysical process. Each component has different spectral properties and features that it is important to investigate in view of a possible, future detection. In this contribution, we will review recent theoretical predictions for backgrounds produced by extragalactic sources and discuss their detectability with current and future gravitational wave observatories.Comment: 10 pages, 9 figures, proceedings of the GWDAW 10 Conference, submitted to Class. & Quantum Gra

The application of semiconductors to quasi- optical and waveguide isolators for use at millimeter wavelengths

Utilization of anisotropic effects in semiconductor plasmas for development of millimeter wavelength isolator