Abstract: We present results on the digital quantum simulations of beam-splitter and squeezing interactions. The bosonic Hamiltonians are mapped to qubits and then digitalized in order to implement them in the IBM quantum devices. We use error mitigation and postselection to achieve high-fidelity digital quantum simulations of single-mode and two-mode interactions, as evinced-where possible-by full tomography of the resulting states. We achieve fidelities above 90% in the case of single-mode squeezing with low squeezing […]
Abstract: Dirac energy dispersions are responsible for the extraordinary transport properties of graphene. This motivated the quest for engineering such energy dispersions also in photonics, where they have been predicted to lead to many exciting phenomena. One paradigmatic example is the possibility of obtaining power-law, decoherence-free, photon-mediated interactions between quantum emitters when they interact with such photonic baths. This prediction, however, has been obtained either by using toy-model baths, which neglect polarization effects, or by […]
Abstract: We report the detection of two isomers of ethynyl cyclopentadiene (c-C5H5CCH), namely 1- and 2-ethynyl-1,3-cyclopentadiene, in the direction of TMC-1. We derive column densities of (1.4 +/- 0.2) x 10(12) cm(-2) and (2.0 +/- 0.4) x 10(12) cm(-2), respectively, for these two cyclopentadiene derivatives, which imply that they are about ten times less abundant than cyclopentadiene. We also report the tentative […]
Abstract: The reaction system between the simplest Criegee intermediate, CH2OO, and the greenhouse gas CO2 has been investigated by Fourier transform microwave spectroscopy. The CH2OO-CO2 weakly bound complex was identified in the rotational spectrum, where inversion doublets due to the tunnelling motion between two equivalent configurations of the complex, with CO2 located at one side or the other side of the CH2OO plane, were observed. Using a two-state torsion-rotation Hamiltonian, […]
Abstract: We have computed the rate of collisional cooling of a gas by H-2 molecules under conditions appropriate to the primordial and interstellar media. We incorporated the results of recent calculations of the rate coefficients for collisional excitation of H-2 by H and H+, which arc essential to a reliable evaluation of the ortho:para H-2 ratio and the cooling rate. Comparison is […]
Abstract: In this work, momentum-space decoherence using minimum and nonminimum-uncertainty-product (stretched) Gaussian wave packets in the framework of Caldeira-Leggett formalism and under the presence of a linear potential is studied. As a dimensionless measure of decoherence, purity, a quantity appearing in the definition of the linear entropy, is studied taking into account the role of the stretching parameter. Special emphasis is on the open dynamics of the well-known cat states and bosons and fermions compared to […]
Abstract: We study the transport of electrons and propagation of the negative ionisation fronts in indium vapour. Electron swarm transport properties are calculated using a Monte Carlo simulation technique over a wide range […]
Abstract: We report a novel and comprehensive analysis of the chlorine anion (Cl-) kinetic energy release distributions (KERDs) from electron transfer experiments at 12, 40 and 118 eV collision energies in the centre-of-mass frame. These distributions have been obtained from the shape and width of Cl- time-of-flight mass spectra from collisions of neutral potassium (K) atoms with a set of selected neutral chlorinated compounds, viz. C6H5Cl, C6D5Cl, C6H11Cl and C6Cl6. […]
Abstract: We report the first detection in interstellar space of the 3-cyano propargyl radical (CH2C3N). This species was observed in the cold dark cloud TMC-1 using the Yebes 40m telescope. A total of seven rotational transitions for both ortho- and para-CH2C3N species were observed in the 31.0-50.4 GHz range. We derive a total column density of (1.6 +/- 0.4) x 10(11) cm(-2) and an ortho/para […]
Abstract: The electronic structure of subnanometric clusters, far off the bulk regime, is still dominated by molecular characteristics. The spatial arrangement of the notoriously undercoordinated metal atoms is strongly coupled to the electronic properties of the system, which makes this class of materials particularly interesting for applications including luminescence, sensing, bioimaging, theranostics, energy conversion, catalysis, and photocatalysis. Opposing a common rule of thumb that assumes an increasing […]
Abstract: We report an experimental and theoretical investigation into the dynamics of electron-impact ionization of the unresolved outermost molecular orbitals (6ag + 1b1g) of pyrazine (C4N2H4). Experimental triple differential cross sections (TDCS) are compared with cross sections calculated within a molecular 3-body distorted wave (M3DW) framework. The M3DW theory was able to reproduce the qualitative scattering behaviour in the binary region, but […]
Abstract: The present paper provides a joint experimental and theoretical study of positron scattering from pyrazine. Experimental data were measured employing a low-energy positron beamline, and covered an energy range from 1 to 79 eV. Cross sections were measured for total scattering, total elastic scattering, positronium formation, direct ionization, and the sum of the total discrete electronic-state […]
Abstract: We report the first identification in space of H2NC, a high-energy isomer of H2CN that has been largely ignored in chemical and astrochemical studies. The observation of various unidentified lines around 72.2 GHz in the cold dark cloud L483 motivated the search and successful detection of additional groups of lines in harmonic relation. Following an exhaustive high-level ab initio screening of possible carriers, we confidently assign the unidentified […]
Abstract: In recent years, combined experimental and theoretical efforts have brought valuable information on the kinetics of reactive collisions between molecular hydrogen and an electronically excited atom X (where X = C (D-1) , N (D-2) , O (D-1) or S (D-1)). These four reactions have been comparatively studied together in numerous occasions in the past due to the similar importance of complex-forming mechanisms found in their overall dynamics. In […]
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