SO(5) Superconductors in a Zeeman Magnetic Field

The generic symmetry of a system under a uniform Zeeman magnetic field is U(1) x U(1). However, we show that SO(5) models in the presence of a finite chemical potential and a finite Zeeman magnetic field can have a exact SU(2) x U(1) symmetry. This principle can be used to test SO(5) symmetry at any doping level

Fixed Point Index for Weakly Inward Mappings

AbstractThe fixed point index for weakly inward mappings, which are not cone mappings, is defined in this paper. Its properties are also investigated. Consequently we study the derivatives of weakly inward mappings and nonzero fixed points of such mappings

Spin swap gate in the presence of qubit inhomogeneity in a double quantum dot

We study theoretically the effects of qubit inhomogeneity on the quantum logic gate of qubit swap, which is an integral part of the operations of a quantum computer. Our focus here is to construct a robust pulse sequence for swap operation in the simultaneous presence of Zeeman inhomogeneity for quantum dot trapped electron spins and the finite-time ramp-up of exchange coupling in a double dot. We first present a geometric explanation of spin swap operation, mapping the two-qubit operation onto a single-qubit rotation. We then show that in this geometric picture a square-pulse-sequence can be easily designed to perform swap in the presence of Zeeman inhomogeneity. Finally, we investigate how finite ramp-up times for the exchange coupling $J$ negatively affect the performance of the swap gate sequence, and show how to correct the problems numerically.Comment: published versio

Helium accumulation effects using bench marked 0-D model

Helium ash'' accumulation is a key issue relative to our ability to achieve a steady-state ignited tokamak. 1-D transport simulations using the BALDUR code have been used to examine the correlation between the global helium particle confinement time and the edge exhaust (or recycling) efficiency. This provides a way to benchmark the widely used 0-D model. In this paper, burn conditions for an ITER-like plasma with various helium edge recycling coefficients are examined

A Wideband Triple-Mode Differentially-Fed Microstrip Patch Antenna

© 2021 IEEE. This is the accepted manuscript version of an article which has been published in final form at https://dx.doi.org/10.1109/LAWP.2021.3074302A wideband differentially-fed microstrip patch antenna (MPA) with tripe-resonant modes is presented in this letter. The proposed triple-mode MPA is realized by combining two dual-mode MPAs (MPA-I and MPA-II) with different resonant frequency ratios. Firstly, the TM0,1 mode and TM0,1/2 mode of dual-mode MPA-I can be concurrently excited by adding a pair of coupling shorted patches beside the strip MPA. The ratio of f0,1/2/f0,1 can be easily adjusted by moving the shorting pins between the strip MPA and shorted patches. Secondly, by properly designing the dimensions of a conventional MPA, the TM0,1 and TM2,1 modes of dual-mode MPA-II are simultaneously excited. To further reduce the ratio of f2,1/f0,1, four slots are elaborately etched on the conventional MPA. Finally, by combining the two dual-mode MPAs, a triple-mode MPA with the frequency ratio of f0,1/2:f2,1:f0,1 = 1.2:1.1:1 is realized. To verify the design concept, a prototype of triple-mode MPA was fabricated and measured. Experimental results show that the proposed microstrip antenna achieves a wide bandwidth of 26.5%, a low cross-polarization of -23 dB, and high harmonic suppression.Peer reviewe

NIP/DuoxA is essential for Drosophila embryonic development and regulates oxidative stress response

NIP/DuoxA, originally cloned as a protein capable of binding to the cell fate determinant Numb in Drosophila, was recently identified as a modulator of reactive oxygen species (ROS) production in mammalian systems. Despite biochemical and cellular studies that link NIP/DuoxA to the generation of ROS through the dual oxidase (Duox) enzyme, the in vivo function of NIP/DuoxA has not been characterized to date. Here we report a genetic and functional characterization of nip in Drosophila melanogaster. We show that nip is essential for Drosophila development as nip null mutants die at the 1st larval instar. Expression of UAS-nip, but not UAS-Duox, rescued the lethality. To understand the function of nip beyond the early larval stage, we generated GAL4 inducible UAS-RNAi transgenes. daG32-GAL4 driven, ubiquitous RNAi-mediated silencing of nip led to profound abnormality in pre-adult development, crinkled wing and markedly reduced lifespan at 29°C. Compared to wild type flies, da-GAL4 induced nip-RNAi transgenic flies exhibited significantly reduced ability to survive under oxidative stress and displayed impaired mitochondrial aconitase function. Our work provides in vivo evidence for a critical role for nip in the development and oxidative stress response in Drosophila

Quantum phase transition in the Frenkel-Kontorova chain: from pinned instanton glass to sliding phonon gas

We study analytically and numerically the one-dimensional quantum Frenkel-Kontorova chain in the regime when the classical model is located in the pinned phase characterized by the gaped phonon excitations and devil's staircase. By extensive quantum Monte Carlo simulations we show that for the effective Planck constant $\hbar$ smaller than the critical value $\hbar_c$ the quantum chain is in the pinned instanton glass phase. In this phase the elementary excitations have two branches: phonons, separated from zero energy by a finite gap, and instantons which have an exponentially small excitation energy. At $\hbar=\hbar_c$ the quantum phase transition takes place and for $\hbar>\hbar_c$ the pinned instanton glass is transformed into the sliding phonon gas with gapless phonon excitations. This transition is accompanied by the divergence of the spatial correlation length and appearence of sliding modes at $\hbar>\hbar_c$.Comment: revtex 16 pages, 18 figure

Merging binary black holes formed through double-core evolution

Context. To date, various formation channels of merging events have been heavily explored with the detection of nearly 100 double black hole (BH) merger events reported by the LIGO-Virgo-KAGRA (LVK) Collaboration. In this paper, we systematically investigate an alternative formation scenario: binary BHs (BBHs) formed through double helium stars (hereafter, “double-core evolution channel”). In this scenario, two helium stars (He-rich stars) could be the outcome of the classical isolated binary evolution scenario with and without the common envelope (CE) phase (i.e., CE channel and stable mass transfer channel) or, alternatively, of massive close binaries evolving chemically homogeneously (i.e., CHE channel). Aims. We study the properties (i.e., the chirp masses and the effective spins) of BBHs formed through the double-core evolution and investigate the impact of different efficiencies of angular momentum transport within massive He-rich stars on double-core evolution. Methods. We performed detailed stellar structure and binary evolution calculations that take into account internal rotation and mass loss of He-rich stars as well as tidal interactions in binaries. We systematically studied the parameter space of initial binary He-rich stars, including the initial mass and metallicity of He-rich stars as well as initial orbital periods. Apart from direct core collapse with mass and angular momentum conserved, we also follow the framework in Batta & Ramirez-Ruiz (2019, ArXiv e-prints [arXiv:1904.04835]) to estimate the mass and spin of the resulting BHs. Results. We show that the radii of massive He-rich stars decrease as a function of time, which comes mainly from mass loss and mixing in high metallicity and from mixing in low metallicity. For double He-rich stars with equal masses in binaries, we find that tides start to be at work on the zero age helium main sequence (i.e., the time when a He-rich star starts to burn helium in the core, which is analogous to zero age main sequence for core hydrogen burning) for initial orbital periods not longer than 1.0 day, depending on the initial metallicities. In addition to the stellar mass-loss rate and tidal interactions in binaries, we find that the role of the angular momentum transport efficiency in determining the resulting BH spins becomes stronger when considering BH progenitors originated from a higher metal-metallicity environment. We highlight that the double-core evolution scenario does not always produce fast-spinning BBHs and compare the properties of the BBHs reported from the LVK with our modeling. Conclusions. After detailed binary calculations of double-core evolution, we have confirmed that the spin of the BH is not only determined by the interplay of the binary’s different initial conditions (metallicity, mass, and orbital period) but is also dependent on the angular momentum transport efficiency within its progenitor. We predict that with the sensitivity improvements to the LVK’s next observing run (O4), the sample of merging BBHs will contain more sources with positive but moderate (even high) χeff and part of the events will likely show to have been formed through the double-core evolution channel

Detecting the Most Distant (z>7) Objects with ALMA

Detecting and studying objects at the highest redshifts, out to the end of Cosmic Reionization at z>7, is clearly a key science goal of ALMA. ALMA will in principle be able to detect objects in this redshift range both from high-J (J>7) CO transitions and emission from ionized carbon, [CII], which is one of the main cooling lines of the ISM. ALMA will even be able to resolve this emission for individual targets, which will be one of the few ways to determine dynamical masses for systems in the Epoch of Reionization. We discuss some of the current problems regarding the detection and characterization of objects at high redshifts and how ALMA will eliminate most (but not all) of them.Comment: to appear in Astrophysics and Space Science, "Science with ALMA: a new era for Astrophysics", ed. R. Bachille

Percolation on two- and three-dimensional lattices

In this work we apply a highly efficient Monte Carlo algorithm recently proposed by Newman and Ziff to treat percolation problems. The site and bond percolation are studied on a number of lattices in two and three dimensions. Quite good results for the wrapping probabilities, correlation length critical exponent and critical concentration are obtained for the square, simple cubic, HCP and hexagonal lattices by using relatively small systems. We also confirm the universal aspect of the wrapping probabilities regarding site and bond dilution.Comment: 15 pages, 6 figures, 3 table