Dynamic Molecular Switches Drive Negative Memristance Mimicking Synaptic Behavior

To realize molecular scale electrical operations beyond the von Neumann bottleneck, new types of multi-functional switches are needed that mimic self-learning or neuromorphic computing by dynamically toggling between multiple operations that depend on their past. Here we report a molecule that switches from high to low conductance states with massive negative memristive behavior that depends on the drive speed and the number of past switching events. This dynamic molecular switch emulates synaptic behavior and Pavlovian learning and can provide all of the fundamental logic gates because of its time-domain and voltage-dependent plasticity. This multi-functional switch represents molecular scale hardware operable in solid-state devices opening a pathway to dynamic complex electrical operations encoded within a single ultra-compact component.

CSRR-DGS Bandpass Filter Based on Half Mode Substrate Integrated Waveguide for X-Band Applications

In this paper, a half mode substrate integrated waveguide (HMSIW) bandpass filter using defected ground structure cells (DGS) is proposed. By using the periodic square CSRR resonant properties of DGS according to design requirement, an X-band band-pass filter is designed and analyzed to meet compact size, low insertion loss, and high rejection. The simulation results obtained by CST in X-band show that the proposed filter is characterized by a large transmitted bandwidth of about 1.38 GHz from 13.03 to 14.41 GHz. The higher simulated insertion loss is about −2.6 dB and the lower return loss is about −34 dB. The proposed filter size is 9.50 × 38.00 mm2 which make it a compact component. The structure is optimized using CST simulator. For the proposal validation, the simulation results is compared by HFSS. The simulation results are in good agreement for the two simulator.

X(6200) as a compact tetraquark in the QCD string model

Recently the LHCb Collaboration announced the first observation of nontrivial structures in the double-$$J/\psi $$ J / ψ mass spectrum in the mass range 6.2–7.2 GeV, and a theoretical coupled-channel analysis of these data performed in Dong et al. (Phys Rev Lett 126:132001, 2021) evidenced the existence of a new state X(6200) close to the double-$$J/\psi $$ J / ψ threshold. Although its molecular interpretation seems the most plausible assumption, the present data do not exclude an admixture of a compact component in its wave function, for which a fully-charmed compact tetraquark is the most natural candidate. It is argued in this work that the QCD string model is compatible with the existence of a compact $$cc{\bar{c}}{\bar{c}}$$ c c c ¯ c ¯ state bound by QCD forces just below the double-$$J/\psi $$ J / ψ threshold. A nontrivial interplay of the quark dynamics associated with this compact state and the molecular dynamics provided by soft gluon exchanges between $$J/\psi $$ J / ψ mesons is discussed and the physical X(6200) is argued to be a shallow bound state, in agreement with the results of the aforementioned coupled-channel analysis of the LHCb data.

Highly-Efficient thin Film LiNbO3 Surface Couplers Connected by Ridge-Waveguide Subwavelength Gratings

The ridge waveguide integrated grating couplers (GCs) in lithium niobate on insulator (LiNbO 3 , LNOI) were designed, fabricated and characterized. Two ends of the gratings structures were connected through the middle photonic rib-waveguide of a sub-micrometric-diameter, which was nanostructured with the geometry of side-wall corrugated subwavelength gratings structure. A high coupling efficiency of -5.1 dB for the best thin film LiNbO 3 (TFLN) grating coupler was measured at the telecommunication wavelength of 1561 nm for quasi-transverse-electric (TE) polarized signals, with a broad 3-dB optical bandwidth of wider than 95 nm. All the devices structure patterns for the integrated LNOI GCs could be simultaneously defined by one step of electron-beam lithography, and then easily fabricated by the dry-etching processes. This compact component exhibited magnificent performance, and might show the potential functionalities for the TFLN-based integrated optical waveguide devices.

Lyman-α emission from a WISE-selected optically faint powerful radio galaxy M151304.72-252439.7 at z = 3.132*

We report the detection of a large (∼90 kpc) and luminous Lyα nebula [LLyα = (6.80±0.08) × 1044 $\rm {\, erg\, s^{-1}}$] around an optically faint (r>23 mag) radio galaxy M1513-2524 at zem=3.132. The double-lobed radio emission has an extent of 184 kpc, but the radio core, i.e., emission associated with the active galactic nucleus (AGN) itself, is barely detected. This object was found as part of our survey to identify high-z quasars based on Wide-field Infrared Survey Explorer (WISE) colors. The optical spectrum has revealed Lyα, N v, C iv and He ii emission lines with a very weak continuum. Based on long-slit spectroscopy and narrow band imaging centered on the Lyα emission, we identify two spatial components: a “compact component” with high velocity dispersion (∼1500 km s−1) seen in all three lines, and an “extended component”, having low velocity dispersion (i.e., 700-1000 km s−1). The emission line ratios are consistent with the compact component being in photoionization equilibrium with an AGN. We also detect spatially extended associated Lyα absorption, which is blue-shifted within 250-400 km s−1 of the Lyα peak. The probability of Lyα absorption detection in such large radio sources is found to be low (∼10%) in the literature. M1513-2524 belongs to the top few percent of the population in terms of Lyα and radio luminosities. Deep integral field spectroscopy is essential for probing this interesting source and its surroundings in more detail.

A Compact Component for Multi-Band Rejection and Frequency Coding in the Plasmonic Circuit at Microwave Frequencies

Plasmonic circuits, which support the propagation of spoof surface plasmon polaritons (SSPPs) at microwave frequencies, have been developed in recent years as an expected candidate for future highly integrated systems, mainly because of their extraordinary field confinements and sub-wavelength resolution. On the other hand, artificial electromagnetic (EM) resonators are widely adopted in metamaterial design for flexible resonance and band gaps. In this work, an electrically small complementary spiral, which is made up of six helix branches sculptured in the ground, is proposed to achieve independent resonances at six different frequency bands. Combined with the grounded corrugated transmission line (TL), the proposed component can provide designable multi-band rejection, and compose frequency coding circuits with a compact size (less than λ0/4). The complementary spirals excited with the bending TL and the straight one are both investigated, and independence band rejections and designed 6-bit coding sequences in the frequency spectrum are demonstrated numerically and experimentally. Hence, it is concluded that such compact components can be adopted to flexibly control the rejection of waves in multi-frequency bands, and benefits the development of frequency-identification circuits and systems.

Ultracompact H ii regions with extended emission: the case of G43.89–0.78 and its molecular environment

ABSTRACT The Karl Jansky Very Large Array (VLA), Owens Valley Radio Observatory (OVRO), Atacama Large Millimetric Array (ALMA), and the infrared Spitzer observatories are powerful facilities to study massive star formation regions and related objects such as ultra-compact (UC) H ii regions, molecular clumps, and cores. We used these telescopes to study the UC H ii region G43.89–0.78. The morphological study at arcminute scales using NVSS and Spitzer data shows that this region is similar to those observed in the bubble-like structures revealed by Spitzer observations. With this result, and including a physical characterization based on 3.6 cm data, we suggest G43.89–0.78 be classified as an UC H ii region with Extended Emission because it meets the operational definition given in this paper comparing radio continuum data at 3.6 and 20 cm. For the ultra-compact component, we use VLA data to obtain physical parameters at 3.6 cm confirming this region as an UC H ii region. Using ALMA observations, we detect the presence of a dense (2.6 × 107 cm−3) and small (∼ 2.0 arcsec; 0.08 pc) molecular clump with a mass of 220 M⊙ and average kinetic temperature of 21 K, located near to the UC H ii region. In this clump, catalogued as G43.890–0.784, water masers also exist, possibly tracing a bipolar outflow. We discover in this vicinity two additional clumps which we label as G43.899–0.786 (Td = 50 K; M = 11 M⊙) and G43.888–0.787 (Td = 50 K; M = 15 M⊙).

A parsec-scale radio jet launched by the central intermediate-mass black hole in the dwarf galaxy SDSS J090613.77+561015.2

ABSTRACT The population of intermediate-mass black holes (IMBHs) in nearby dwarf galaxies plays an important ‘ground truth’ role in exploring black hole formation and growth in the early Universe. In the dwarf elliptical galaxy SDSS J090613.77+561015.2 (z = 0.0465), an accreting IMBH has been revealed by optical and X-ray observations. Aiming to search for possible radio core and jet associated with the IMBH, we carried out very long baseline interferometry (VLBI) observations with the European VLBI Network at 1.66 GHz. Our imaging results show that there are two 1-mJy components with a separation of about 52 mas (projected distance 47 pc) and the more compact component is located within the 1σ error circle of the optical centroid from available Gaia astrometry. Based on their positions, elongated structures and relatively high brightness temperatures, as well as the absence of star-forming activity in the host galaxy, we argue that the radio morphology originates from the jet activity powered by the central IMBH. The existence of the large-scale jet implies that violent jet activity might occur in the early epochs of black hole growth and thus help to regulate the co-evolution of black holes and galaxies.

3C 294 revisited: Deep Large Binocular Telescope AO NIR images and optical spectroscopy

Context. High redshift radio galaxies are among the most massive galaxies at their redshift, are often found at the center of protoclusters of galaxies, and are expected to evolve into the present day massive central cluster galaxies. Thus they are a useful tool to explore structure formation in the young Universe. Aims. 3C 294 is a powerful FR II type radio galaxy at z = 1.786. Past studies have identified a clumpy structure, possibly indicative of a merging system, as well as tentative evidence that 3C 294 hosts a dual active galactic nucleus (AGN). Due to its proximity to a bright star, it has been subject to various adaptive optics imaging studies. Methods. In order to distinguish between the various scenarios for 3C 294, we performed deep, high-resolution adaptive optics near-infrared imaging and optical spectroscopy of 3C 294 with the Large Binocular Telescope. Results. We resolve the 3C 294 system into three distinct components separated by a few tenths of an arcsecond on our images. One is compact, the other two are extended, and all appear to be non-stellar. The nature of each component is unclear. The two extended components could be a galaxy with an internal absorption feature, a galaxy merger, or two galaxies at different redshifts. We can now uniquely associate the radio source of 3C 294 with one of the extended components. Based on our spectroscopy, we determined a redshift of z = 1.784 ± 0.001, which is similar to the one previously cited. In addition we found a previously unreported emission line at λ6749.4 Å in our spectra. It is not clear that it originates from 3C 294. It could be the Ne [IV] doublet λ2424/2426 Å at z = 1.783, or belong to the compact component at a redshift of z ∼ 4.56. We thus cannot unambiguously determine whether 3C 294 hosts a dual AGN or a projected pair of AGNs.