Catálogo de publicaciones - revistas

<jats:p>We performed high-pressure transport studies on the flat-band Kagome compounds, Pd<jats:sub>3</jats:sub>P<jats:sub>2</jats:sub>(S<jats:sub>1 – <jats:italic>x</jats:italic> </jats:sub>Se<jats:sub> <jats:italic>x</jats:italic> </jats:sub>)<jats:sub>8</jats:sub> (<jats:italic>x</jats:italic> = 0, 0.25), with a diamond anvil cell. For both compounds, the resistivity exhibits an insulating behavior with pressure up to 17 GPa. With pressure above 20 GPa, a metallic behavior is observed at high temperatures in Pd<jats:sub>3</jats:sub>P<jats:sub>2</jats:sub>S<jats:sub>8</jats:sub>, and superconductivity emerges at low temperatures. The onset temperature of superconducting transition <jats:italic>T</jats:italic> <jats:sub>C</jats:sub> rises monotonically from 2 K to 4.8 K and does not saturate with pressure up to 43 GPa. For the Se-doped compound Pd<jats:sub>3</jats:sub>P<jats:sub>2</jats:sub>(S<jats:sub>0.75</jats:sub>Se<jats:sub>0.25</jats:sub>)<jats:sub>8</jats:sub>, the <jats:italic>T</jats:italic> <jats:sub>C</jats:sub> is about 1.5 K higher than that of the undoped one over the whole pressure range, and reaches 6.4 K at 43 GPa. The upper critical field with field applied along the <jats:italic>c</jats:italic> axis at typical pressures is about 50% of the Pauli limit, suggesting a 3D superconductivity. The Hall coefficient in the metallic phase is low and exhibits a peaked behavior at about 30 K, which suggests either a multi-band electronic structure or an electron correlation effect in the system.</jats:p>

<jats:p>Numerous investigations have been conducted to explore the structural phase transition in antiferromagnetic 3<jats:italic>d</jats:italic> transition metal monoxides accompanied by appearance of magnetic phase transition. However, how the spins induce distortion in the high symmetric structure has not yet been fully understood. In this study, the monoxide NiO is used as an example to investigate what lowers the structural symmetry. By comparing two different magnetic structures, our results reveal that the spin–lattice coupling is responsible for such a structural distortion. Then, a spin–lattice model, including the strain component, is constructed to simulate the transition procedure. Moreover, the results from the first-principles calculations are used to compare with our model results. Both first-principles calculations and model simulations clarify the structural phase transition caused by a unique magnetic arrangement.</jats:p>

<jats:p>In the context of tensor network states, we for the first time reformulate the corner transfer matrix renormalization group (CTMRG) method into a variational bilevel optimization algorithm. The solution of the optimization problem corresponds to the fixed-point environment pursued in the conventional CTMRG method, from which the partition function of a classical statistical model, represented by an infinite tensor network, can be efficiently evaluated. The validity of this variational idea is demonstrated by the high-precision calculation of the residual entropy of the dimer model, and is further verified by investigating several typical phase transitions in classical spin models, where the obtained critical points and critical exponents all agree with the best known results in literature. Its extension to three-dimensional tensor networks or quantum lattice models is straightforward, as also discussed briefly.</jats:p>

<jats:p>Antiferromagnetic materials are exciting quantum materials with rich physics and great potential for applications. On the other hand, an accurate and efficient theoretical method is highly demanded for determining critical transition temperatures, Néel temperatures, of antiferromagnetic materials. The powerful graph neural networks (GNNs) that succeed in predicting material properties lose their advantage in predicting magnetic properties due to the small dataset of magnetic materials, while conventional machine learning models heavily depend on the quality of material descriptors. We propose a new strategy to extract high-level material representations by utilizing self-supervised training of GNNs on large-scale unlabeled datasets. According to the dimensional reduction analysis, we find that the learned knowledge about elements and magnetism transfers to the generated atomic vector representations. Compared with popular manually constructed descriptors and crystal graph convolutional neural networks, self-supervised material representations can help us to obtain a more accurate and efficient model for Néel temperatures, and the trained model can successfully predict high Néel temperature antiferromagnetic materials. Our self-supervised GNN may serve as a universal pre-training framework for various material properties.</jats:p>

<jats:p>The human brain that relies on neural networks communicated by spikes is featured with ultralow energy consumption, which is more robust and adaptive than any digital system. Inspired by the spiking framework of the brain, spike-based neuromorphic systems have recently inspired intensive attention. Therefore, neuromorphic devices with spike-based synaptic functions are considered as the first step toward this aim. Photoelectric neuromorphic devices are promising candidates for spike-based synaptic devices with low latency, broad bandwidth, and superior parallelism. Here, the indium-gallium-zinc-oxide-based photoelectric neuromorphic transistors are fabricated for Morse coding based on spike processing, 405-nm light spikes are used as synaptic inputs, and some essential synaptic plasticity, including excitatory postsynaptic current, short-term plasticity, and high-pass filtering, can be mimicked. More interestingly, Morse codes encoded by light spikes are decoded using our devices and translated into amplitudes. Furthermore, such devices are compatible with standard integrated processes suitable for large-scale integrated neuromorphic systems.</jats:p>

<jats:p>Quantum key distribution (QKD) generates information-theoretical secret keys between two parties based on the physical laws of quantum mechanics. Following the advancement in quantum communication networks, it becomes feasible and economical to combine QKD with classical optical communication through the same fiber using dense wavelength division multiplexing (DWDM) technology. This study proposes a detailed scheme of TF-QKD protocol with DWDM technology and analyzes its performance, considering the influence of quantum channel number and adjacent quantum crosstalk on the secret key rates. The simulation results show that the scheme further increases the secret key rate of TF-QKD and its variants. Therefore, this scheme provides a method for improving the secret key rate for practical quantum networks.</jats:p>

<jats:p>Quantum steering in a global state allows an observer to remotely steer a subsystem into different ensembles by performing different local measurements on the other part. We show that, in general, this property cannot be perfectly cloned by any joint operation between a steered subsystem and a third system. Perfect cloning is viable if and only if the initial state is of zero discord. We also investigate the process of cloning the steered qubit of a Bell state using a universal cloning machine. Einstein–Podolsky–Rosen (EPR) steering, which is a type of quantum correlation existing in the states without a local-hidden-state model, is observed in the two copy subsystems. This contradicts the conclusion of <jats:italic>no-cloning of quantum steering (EPR steering)</jats:italic> [C. Y. Chiu <jats:italic>et al.</jats:italic>, npj Quantum Inf. <jats:bold>2</jats:bold>, 16020 (2016)] based on a mutual information criterion for EPR steering.</jats:p>

<jats:p>By quenching the interatomic interactions, we investigate the nonequilibrium dynamics of two-dimensional Bose–Einstein condensates in boxlike traps with power-law potential boundaries. We show that ring dark solitons can be excited during the quench dynamics for both concave and convex potentials. The quench’s modulation strength and the steepness of the boundary are two major factors influencing the system’s evolution. In terms of the number of ring dark solitons excited in the condensate, five dynamic regimes have been identified. The condensate undergoes damped radius oscillation in the absence of ring dark soliton excitations. When it comes to the appearance of ring dark solitons, their decay produces interesting structures. The excitation patterns for the concave potential show a nested structure of vortex-antivortex pairs. The dynamic excitation patterns for the convex potential, on the other hand, show richer structures with multiple transport behaviors.</jats:p>

<jats:p>The quantum chromodynamics (QCD) coupling <jats:italic>α</jats:italic> <jats:sub>s</jats:sub> is the most important parameter for achieving precise QCD predictions. By using the well measured effective coupling <jats:inline-formula> <jats:tex-math><?CDATA ${\alpha }_{{\rm{s}}}^{{g}_{1}}(Q)$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi>α</mml:mi> <mml:mi mathvariant="normal">s</mml:mi> <mml:mrow> <mml:msub> <mml:mi>g</mml:mi> <mml:mn>1</mml:mn> </mml:msub> </mml:mrow> </mml:msubsup> <mml:mo stretchy="false">(</mml:mo> <mml:mi>Q</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpl_39_7_071201_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> defined from the Bjorken sum rules as a basis, we suggest a novel self-consistency way to fix the <jats:italic>α</jats:italic> <jats:sub>s</jats:sub> at all scales: The QCD light-front holographic model is adopted for its infrared behavior, and the fixed-order pQCD prediction under the principle of maximum conformality (PMC) is used for its high-energy behavior. Using the PMC scheme-and-scale independent perturbative series, and by transforming it into the one under the physical V scheme, we observe that a precise <jats:italic>α</jats:italic> <jats:sub>s</jats:sub> running behavior in both the perturbative and nonperturbative domains with a smooth transition from small to large scales can be achieved.</jats:p>