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<jats:p>The solutions of the problems related to open quantum systems have attracted considerable interest. We propose a variational quantum algorithm to find the steady state of open quantum systems. In this algorithm, we employ parameterized quantum circuits to prepare the purification of the steady state and define the cost function based on the Lindblad master equation, which can be efficiently evaluated with quantum circuits. We then optimize the parameters of the quantum circuit to find the steady state. Numerical simulations are performed on the one-dimensional transverse field Ising model with dissipative channels. The result shows that the fidelity between the optimal mixed state and the true steady state is over 99%. This algorithm is derived from the natural idea of expressing mixed states with purification and it provides a reference for the study of open quantum systems.</jats:p>

<jats:p>Understanding why the scale of emergent hadron mass is obvious in the proton but hidden in the pion may rest on mapping the distribution functions (DFs) of all partons within the pion and comparing them with those in the proton; and since glue provides binding in quantum chromodynamics, the glue DF could play a special role. Producing reliable predictions for the proton’s DFs is difficult because the proton is a three-valence-body bound-state problem. As sketched herein, the situation for the pion, a two-valence-body problem, is much better, with continuum and lattice predictions for the valence-quark and glue DFs in agreement. This beginning of theory alignment is timely because experimental facilities now either in operation or planning promise to realize the longstanding goal of providing pion <jats:italic>targets</jats:italic>, thereby enabling precision experimental tests of rigorous theory predictions concerning Nature’s most fundamental Nambu–Goldstone bosons.</jats:p>

<jats:p>We provide a concise review on recent theory advancements towards full-fledged (3+1)D dynamical descriptions of relativistic nuclear collisions at finite baryon density. Heavy-ion collisions at different collision energies produce strongly coupled matter and probe the QCD phase transition at the crossover, critical point, and first-order phase transition regions. Dynamical frameworks provide a quantitative tool to extract properties of hot QCD matter and map fireballs to the QCD phase diagram. Outstanding challenges are highlighted when confronting current theoretical frameworks with current and forthcoming experimental measurements from the RHIC beam energy scan programs.</jats:p>

<jats:p>We revisit the laser-intensity-dependent ionization and fragmentation yields of C<jats:sub>60</jats:sub> molecules irradiated by 25-fs, 798-nm laser pulses based on the approach in which photoions are measured via a velocity map imaging spectrometer working in a time-sliced mode. This approach dramatically improves the signal-to-background ratio compared to those using a simple (traditional) time-of-flight mode (spectrometer), and thus allows us to measure the laser-intensity dependences down to a previously untouched region, which is expected to provide new insights into the intense-field ionization and fragmentation of C<jats:sub>60</jats:sub>. Indeed, we find that the saturation intensities for C<jats:sub>60</jats:sub> ionizations and the onset intensity for C<jats:sub>60</jats:sub> fragmentation are much lower than those reported in previous experiments. Furthermore, the derived saturation-intensity dependence on charge distribution demonstrates the validity of the over-the-barrier ionization using a conducting sphere model.</jats:p>

<jats:p>A photon source with high-dimensional entanglement is able to bring increasing capacity of information in quantum communication. The dimensionality is determined by the chosen degree of freedom of the photons and is limited by the complexity of the physical systems. Here we propose a new type of high-dimensional entangled photon source, generated via path-indistinguishable scheme from a two-dimensional atomic cloud, which is prepared in a magneto-optical trap. To verify the photon source, we demonstrate experimentally the quantum state of the single photons heralded by its partner photon, with homodyne tomographic technology.</jats:p>

<jats:p>We propose a controllable exponential-Cosine Gaussian vortex (ECGV) beam, which can evolve into the different beam profiles with three parameters: distance modulation factor (DMF), split modulation factor (SMF) and rotation modulation factor (RMF). When SMF is 0, the ECGV beam appears as a perfect single-ring vortex beam and the ring radius can be adjusted by the DMF. We deduce from mathematics and give the reason for the single-ring characteristics. When SMF is not 0, the beam splits symmetrically. DMF, SMF and RMF control the number, distance and rotation angle of the split, respectively. Our experiments verify the correctness of the theory.</jats:p>

<jats:p>It is well known that spatial symmetry in a photonic crystal (PhC) slab is capable of creating bound states in the continuum (BICs), which can be characterized by topological charges of polarization vortices. Here, we show that when a PT-symmetric perturbation is introduced into the PhC slab, a new type of BICs (<jats:italic>pt</jats:italic>-BICs) will arise from each ordinary BIC together with the creation of rings of lasing threshold modes with <jats:italic>pt</jats:italic>-BICs embedded in these rings. Different from ordinary BICs, the <jats:italic>Q</jats:italic>-factor divergence rate of a <jats:italic>pt</jats:italic>-BIC is reduced and anisotropic in momentum space. Also, <jats:italic>pt</jats:italic>-BICs can even appear at off-high symmetry lines of the Brillouin zone. The <jats:italic>pt</jats:italic>-BICs also carry topological charges and can be created or annihilated with the total charge conserved. A unified picture on <jats:italic>pt</jats:italic>-BICs and the associated lasing threshold modes is given based on the temporal coupled mode theory. Our findings reveal the new physics arising from the interplay between PT symmetry and BIC in PhC slabs.</jats:p>

<jats:p>We theoretically study the Casimir interaction between Weyl semimetals. When the distance <jats:italic>a</jats:italic> between semi-infinite Weyl semimetals is in the micrometer regime, the Casimir attraction can be enhanced by the chiral anomaly. The Casimir attraction depends sensitively on the relative orientations between the separations (<jats:italic> <jats:bold>b</jats:bold> </jats:italic> <jats:sub>1</jats:sub>, <jats:italic> <jats:bold>b</jats:bold> </jats:italic> <jats:sub>2</jats:sub>) of Weyl nodes in the Brillouin zone and show anisotropic behavior for the relative orientation of these separations (<jats:italic> <jats:bold>b</jats:bold> </jats:italic> <jats:sub>1</jats:sub>, <jats:italic> <jats:bold>b</jats:bold> </jats:italic> <jats:sub>2</jats:sub>) when they orient parallel to the interface. This anisotropy is quite larger than that in conventional birefringent materials. The Casimir force can be repulsive in the micrometer regime if the Weyl semimetal slabs are sufficiently thin and the direction of Weyl nodes separations (<jats:italic> <jats:bold>b</jats:bold> </jats:italic> <jats:sub>1</jats:sub>, <jats:italic> <jats:bold>b</jats:bold> </jats:italic> <jats:sub>2</jats:sub>) is perpendicular to the interface. The Casimir attraction between Weyl semimetal slabs decays slower than 1/<jats:italic>a</jats:italic> <jats:sup>4</jats:sup> when the Weyl nodes separations <jats:italic> <jats:bold>b</jats:bold> </jats:italic> <jats:sub>1</jats:sub> and <jats:italic> <jats:bold>b</jats:bold> </jats:italic> <jats:sub>2</jats:sub> are both parallel to the interface.</jats:p>

<jats:p>The excitation condition of reversed shear Alfvén eigenmodes (RSAEs) has been investigated during sawtooth-like oscillation in the EAST tokamak. The sawtooth-like phenomena can be reproduced in the configuration of reversed magnetic shear, and the threshold gradient of electron temperature is formed accordingly, together with the increasing of the confinement of thermal particles. The distribution function of energetic ions density is altered dramatically when the neutral beam is switched from NBI1L (tangent) to NBI1R (perpendicular), which can be captured by the measurement of radial neutron camera. The RSAEs are excited easily in the vicinity of <jats:italic>q</jats:italic> <jats:sub>min</jats:sub> (1.99 m ≤ <jats:italic>R</jats:italic> ≤ 2.06 m) for the injection of neutral beam with perpendicular direction, which should be excited by the steep gradient of energetic ions density. Furthermore, the excitation of RSAEs and the formation of threshold gradient of electron temperature can take place concurrently, which means that the neutral beam with perpendicular injection is beneficial for the establishment of internal transport barrier.</jats:p>

<jats:p>The kinetic effects of thermal particles and fast ions on internal kink (IK) mode are numerically investigated by the MHD-kinetic hybrid code MARS-K. It is shown that either thermal particles or fast ions have stabilizing influence on IK. However, the former can not fully stabilize IK, and the later can suppress the IK. In addition, the synergistic effect from thermal particles and fast ions induces more stronger damping on IK. The kinetic effects from particles significantly raise the critical value of poloidal beta (<jats:inline-formula> <jats:tex-math><?CDATA ${\beta }_{{\rm{p}}}^{{\rm{crit}}}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi>β</mml:mi> <mml:mi mathvariant="normal">p</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">crit</mml:mi> </mml:mrow> </mml:msubsup> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpl_38_8_085202_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>) for driving IK in the toroidal plasma. This implies a method of controlling IK or sawtooth in the high-<jats:italic>β</jats:italic> <jats:sub>p</jats:sub> discharge scenario of tokamak. It is noted that, at the <jats:italic>q</jats:italic> = 1 rational surface, mode structure becomes more sharp due to the self-consistent modification by particles’ kinetic effect.</jats:p>