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<jats:p>Dissipation is often considered as a detrimental effect in quantum systems for unitary quantum operations. However, it has been shown that suitable dissipation can be useful resources in both quantum information and quantum simulation. Here, we propose and experimentally simulate a dissipative phase transition (DPT) model using a single trapped ion with an engineered reservoir. We show that the ion’s spatial oscillation mode reaches a steady state after the alternating application of unitary evolution under a quantum Rabi model Hamiltonian and sideband cooling of the oscillator. The average phonon number of the oscillation mode is used as the order parameter to provide evidence for the DPT. Our work highlights the suitability of trapped ions for simulating open quantum systems and shall facilitate further investigations of DPT with various dissipation terms.</jats:p>

<jats:p>Basalt is an igneous rock originating from the cooling and solidification of magma and covers approximately 70% of Earth’s surface. Basaltic glass melting in the deep Earth is a fundamental subject of research for understanding geophysics, geochemistry, and geodynamic processes. In this study, we design a laser flash heating system using two-dimensional, four-color multi-wavelength imaging radiometry to measure the basaltic glass melting temperature under high pressure conditions in diamond anvil cells. Our experiment not only determines the temperature at the center of heating but also constructs a temperature distribution map for the surface heating area, and enables us to assess the temperature gradient. Through precise temperature measurements, we observe that the basaltic glass melting temperature is higher than those in previous reports, which is near the normal upper-mantle isotherm, approaching the hot geotherm. This suggests that basalt should not melt in most of the normal upper mantle and the basaltic melts could exist in some hot regions.</jats:p>

<jats:p>Chiral anomaly and the novel quantum phenomena it induces have been widely studied for Dirac and Weyl fermions. In most typical cases, the Lorentz covariance is assumed and thus the linear dispersion relations are maintained. However, in realistic materials, such as Dirac and Weyl semimetals, the nonlinear dispersion relations appear naturally. We develop a kinetic framework to study the chiral anomaly for Weyl fermions with nonlinear dispersions using the methods of Wigner function and semi-classical equations of motion. In this framework, the chiral anomaly is sourced by Berry monopoles in momentum space and could be enhanced or suppressed due to the windings around the Berry monopoles. Our results can help understand the chiral anomaly-induced transport phenomena in non-relativistic systems.</jats:p>

<jats:p>The above-threshold ionization process of ammonia molecules induced by a femtosecond laser field at 800 nm is studied in the intensity range from 1.6 × 10<jats:sup>13</jats:sup> to 5.7 × 10<jats:sup>13</jats:sup> W/cm<jats:sup>2</jats:sup>. Channel switching under different laser intensities is observed and identified in the photoelectron kinetic energy spectra of ammonia. Based on the photoelectron kinetic energy distributions and the photoelectron angular distributions, the characteristic peaks observed are exclusively assigned to the multiphoton resonance through certain intermediate states, followed by multiphoton above-threshold ionization.</jats:p>

<jats:p>We report an all-fiberized chirped pulse amplification system without any bulk devices. The stretcher and compressor are chirped fiber Bragg gratings inscribed in a 6/125 μm single-mode fiber and a 30/250 μm large-mode-area fiber. The fabrication system of chirped fiber Bragg gratings was designed and built by ourselves. The width of the linear exposure spot was controlled according to the different fiber sizes to improve the fabrication quality, and the parameters of chirped fiber Bragg gratings were fine-tuned during the fabrication to achieve the overall system’s spectral matching. Two fiber circulators with the same fiber sizes as the chirped fiber Bragg gratings were employed to auxiliarily achieve the pulse stretching and compression. The dispersion accumulations provided by the stretcher and compressor are 129.8 ps and 90.8 ps. The power amplifiers were composed of the two-stage 10/130 μm fiber pre-amplifier and the 30/250 μm fiber main amplifier. The proposed chirped pulse amplification system with no spatial light is the true sense of an all-fiberized chirped pulse amplification structure and shows the main trend in development of ultrashort pulse fiber lasers.</jats:p>

<jats:p>Rutherford scattering formula plays an important role in plasma classical transport. It is urgent to investigate influence of magnetic field on the Rutherford scattering since the high magnetic field has been widely used in nowadays magnetic confinement fusion, inertial confinement fusion, and magneto-inertial fusion. In order to elucidate the magnetic field effect in a concise manner, we study the electron-ion collisions transverse to the magnetic field. The scattering angle is defined using the directions of electron velocity before and after collision, which is obtained analytically. It is found that the scattering angle can be influenced by finite magnetic field significantly. The theoretical results agree well with numerical calculation by checking the dependence of scattering angle on the magnetic field.</jats:p>

<jats:p>Lithium superoxides, Li<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>, LiO<jats:sub>2</jats:sub>, and LiO<jats:sub>4</jats:sub>, have been synthesized under high pressure. These materials have potential applications in energy storage devices. Here, we use first-principles calculations to investigate the elastic and Li<jats:sup>+</jats:sup> transport properties of these oxides at high pressure and high temperature. The elastic constants are calculated at 20–80 GPa, and they satisfy the Born stability criteria, indicating the good mechanical stability of these oxides. Their sound velocities calculated with elastic constants are close to each other, but difference in velocity anisotropy is obvious. LiO<jats:sub>2</jats:sub> presents significant shear sound wave anisotropy over 80%. The Li<jats:sup>+</jats:sup> transport properties are investigated using first principles molecular dynamics (FPMD) and climbing-image nudged elastic band methods. The lowest Li<jats:sup>+</jats:sup> migration barrier energies increase from 0.93, 0.86 and 1.22 eV at 20 GPa to 1.43, 1.12 and 1.77 eV at 50 GPa for Li<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>, LiO<jats:sub>2</jats:sub>, and LiO<jats:sub>4</jats:sub>, respectively. The most favorable path for LiO<jats:sub>2</jats:sub> and LiO<jats:sub>4</jats:sub> is along the [001] direction. The FPMD results suggest that these oxides become unstable with increasing temperature up to 2000 K due to O–O dimer clusters in these superoxides. Consequently, a superionic transition is not observed in the simulations.</jats:p>

<jats:p>We observed an isostructural phase transition in the solid nitrogen <jats:italic>λ</jats:italic>-N<jats:sub>2</jats:sub> at approximately 50 GPa accompanied by anomalies in lattice parameters, atomic volume and Raman vibron modes. The anomalies are ascribed to a slight reorientation of the nitrogen molecules, which does not seem to affect the monoclinic symmetry (space group <jats:italic>P</jats:italic>2<jats:sub>1</jats:sub>/<jats:italic>c</jats:italic>). Our <jats:italic>ab initio</jats:italic> calculations further confirm the phenomena, and suggest an optimized structure for the <jats:italic>λ</jats:italic>-N<jats:sub>2</jats:sub> phase. In addition, a new high-pressure amorphous phase of <jats:italic>η</jats:italic>′-N<jats:sub>2</jats:sub> was also discovered by a detailed investigation of the pressure-temperature phase diagram of nitrogen with the aim of probing the phase stability of <jats:italic>λ</jats:italic>-N<jats:sub>2</jats:sub>. Our result may provide helpful information about the crystallographic nature of dissociation transitions in diatomic molecular crystals (H<jats:sub>2</jats:sub>, O<jats:sub>2</jats:sub>, N<jats:sub>2</jats:sub>, etc).</jats:p>

<jats:p>Anisotropic magnetoresistance (AMR) and related planar Hall resistance (PHR) are ubiquitous phenomena of magnetic materials. Although the universal angular dependences of AMR and PHR in magnetic polycrystalline materials with one order parameter are well known, no similar universal relation for other class of magnetic materials are known to date. Here a general theory of galvanomagnetic effects in magnetic materials is presented with two vector order parameters, such as magnetic single crystals with a dominated crystalline axis or polycrystalline non-collinear ferrimagnetic materials. It is shown that AMR and PHR have a universal angular dependence. In general, both longitudinal and transverse resistivity are non-reciprocal in the absence of inversion symmetry: Resistivity takes different values when the current is reversed. Different from simple magnetic polycrystalline materials where AMR and PHR have the same magnitude, and <jats:italic>π</jats:italic>/4 out of phase, the magnitudes of AMR and PHR of materials with two vector order parameters are not the same in general, and the phase difference is not <jats:italic>π</jats:italic>/4. Instead of <jats:italic>π</jats:italic> periodicity of the usual AMR and PHR, the periodicities of materials with two order parameters are 2<jats:italic>π</jats:italic>.</jats:p>

<jats:p>We report the synthesis, crystal structure, and superconductivity of Ti<jats:sub>4</jats:sub>Ir<jats:sub>2</jats:sub>O. The title compound crystallizes in an <jats:italic>η</jats:italic>-carbide type structure of the space group <jats:inline-formula> <jats:tex-math><?CDATA $Fd\bar{3}m$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>F</mml:mi> <mml:mi>d</mml:mi> <mml:mover accent="true"> <mml:mn>3</mml:mn> <mml:mo>¯</mml:mo> </mml:mover> <mml:mi>m</mml:mi> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpl_39_2_027401_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> (No. 227), with lattice parameters <jats:italic>a</jats:italic> = <jats:italic>b</jats:italic> = <jats:italic>c</jats:italic> = 11.6194(1) Å. The superconducting temperature <jats:italic>T</jats:italic> <jats:sub>c</jats:sub> is found to be 5.1–5.7 K. Most surprisingly, Ti<jats:sub>4</jats:sub>Ir<jats:sub>2</jats:sub>O hosts an upper critical field of 16.45 T, which is far beyond the Pauli paramagnetic limit. Strong coupled superconductivity with evidences for multigap is revealed by the measurements of heat capacity and upper critical field. First-principles calculations suggest that the density of states near the Fermi level originates from the hybridization of Ti-3<jats:italic>d</jats:italic> and Ir-5<jats:italic>d</jats:italic> orbitals, and the effect of spin-orbit coupling on the Fermi surfaces is prominent. Large values of the Wilson ratio (<jats:italic>R</jats:italic> <jats:sub>W</jats:sub> ∼ 3.9), the Kadowaki–Woods ratio [<jats:italic>A</jats:italic>/<jats:italic>γ</jats:italic> <jats:sup>2</jats:sup> ∼ 9.0 × 10<jats:sup>−6</jats:sup> μΩ⋅cm/(mJ⋅mol<jats:sup>−1</jats:sup>⋅K<jats:sup>−1</jats:sup>)<jats:sup>2</jats:sup>], and the Sommerfeld coefficient (<jats:italic>γ</jats:italic> = 33.74 mJ⋅mol<jats:sup>−1</jats:sup>⋅K<jats:sup>−2</jats:sup>) all suggest strong electron correlations (similar to heavy fermion systems) in Ti<jats:sub>4</jats:sub>Ir<jats:sub>2</jats:sub>O. The violation of Pauli limit is possibly due to a combination of strong-coupled superconductivity and large spin-orbit scattering. With these intriguing behaviors, Ti<jats:sub>4</jats:sub>Ir<jats:sub>2</jats:sub>O serves as a candidate for unconventional superconductor.</jats:p>