On the thermodynamics of plasticity during quasi-isentropic compression of metallic glass

Entropy production in quasi-isentropic compression (QIC) is critically important for understanding the properties of materials under extremeconditions. However, the origin and accurate quantification of entropy in this situation remain long-standing challenges. In this work, a framework is established for the quantification of entropy production and partition, and their relation to microstructural change in QIC. Cu50Zr50is taken as a model material, and its compression is simulated by molecular dynamics. On the basis of atomistic simulation-informed physicalproperties and free energy, the thermodynamic path is recovered, and the entropy production and its relation to microstructural change aresuccessfully quantified by the proposed framework. Contrary to intuition, entropy production during QIC of metallic glasses is relativelyinsensitive to the strain rate ˙γ when ˙γ ranges from 7.5 × 10^(8) to 2 × 10^(9)/s, which are values reachable in QIC experiments, with a magnitudeof the order of 10^(−2)kB/atom per GPa. However, when ˙γ is extremely high (>2 × 10^(9)/s), a notable increase in entropy production rate with˙γ is observed. The Taylor–Quinney factor is found to vary with strain but not with strain rate in the simulated regime. It is demonstrated thatentropy production is dominated by the configurational part, compared with the vibrational part. In the rate-insensitive regime, the increase inconfigurational entropy exhibits a linear relation to the Shannon-entropic quantification of microstructural change, and a stretched exponential relation to the Taylor–Quinney factor. The quantification of entropy is expected to provide thermodynamic insights into the fundamentalrelation between microstructure evolution and plastic dissipation.

Twin-Capture Rydberg State Excitation Enhanced with Few-Cycle Laser Pulses

Quantum excitation is usually regarded as a transient process occurring instantaneously,leaving the underlying physics shrouded in mystery.Recent research shows that Rydberg-state excitation with ultrashort laser pulses can be investigated and manipulated with state-of-the-art few-cycle pulses.We theoretically find that the efficiency of Rydberg state excitation can be enhanced with a short laser pulse and modulated by varying the laser intensities.We also uncover new facets of the excitation dynamics,including the launching of an electron wave packet through strong-field ionization,the re-entry of the electron into the atomic potential and the crucial step where the electron makes a U-turn,resulting in twin captures into Rydberg orbitals.By tuning the laser intensity,we show that the excitation of the Rydberg state can be coherently controlled on a sub-optical-cycle timescale.Our work paves the way toward ultrafast control and coherent manipulation of Rydberg states,thus benefiting Rydberg-state-based quantum technology.

Strain‑Induced Surface Interface Dual Polarization Constructs PML‑Cu/Bi_(12)O_(17)Br_(2) High‑Density Active Sites for CO_(2) Photoreduction

The insufficient active sites and slow interfacial charge trans-fer of photocatalysts restrict the efficiency of CO_(2) photoreduction.The synchronized modulation of the above key issues is demanding and chal-lenging.Herein,strain-induced strategy is developed to construct the Bi–O-bonded interface in Cu porphyrin-based monoatomic layer(PML-Cu)and Bi_(12)O_(17)Br_(2)(BOB),which triggers the surface interface dual polarization of PML-Cu/BOB(PBOB).In this multi-step polarization,the built-in electric field formed between the interfaces induces the electron transfer from con-duction band(CB)of BOB to CB of PML-Cu and suppresses its reverse migration.Moreover,the surface polarization of PML-Cu further promotes the electron converge in Cu atoms.The introduction of PML-Cu endows a high density of dispersed Cu active sites on the surface of PBOB,significantly promoting the adsorption and activation of CO_(2) and CO desorption.The conversion rate of CO_(2) photoreduction to CO for PBOB can reach 584.3μmol g-1,which is 7.83 times higher than BOB and 20.01 times than PML-Cu.This work offers valuable insights into multi-step polarization regulation and active site design for catalysts.

Heteronuclear Magnetisms with Ultracold Spinor Bosonic Gases in Optical Lattices

Motivated by recent realizations of spin-1 NaRb mixtures in the experiments[Phys.Rev.Lett.114,255301(2015);Phys.Rev.Lett.128,223201(2022)],we investigate heteronuclear magnetism in the Mott-insulating regime.Different from the identical mixtures where the boson statistics only admits even parity states from angular momentum composition,for heteronuclear atoms in principle all angular momentum states are allowed,which can give rise to new magnetic phases.While various magnetic phases can be developed over these degenerate spaces,the concrete symmetry breaking phases depend on not only the degree of degeneracy but also the competitions from many-body interactions.We unveil these rich phases using the bosonic dynamical mean-field theory approach.These phases are characterized by various orders,including spontaneous magnetization order,spin magnitude order,singlet pairing order,and nematic order,which may coexist specially in the regime with odd parity.Finally we address the possible parameter regimes for observing these spin-ordered Mott phases.

Chirp Compensation for Generating Ultrashort Attosecond Pulses with 800-nm Few-Cycle Pulses

We show that it is feasible to generate sub-40-attosecond pulses with near-infrared few-cycle pulses centered at 800 nm.With proper gating technique,super-broadband continuum spectrum extending from 50 eV to above 200 eV can be obtained,and the intrinsic atto-chirp can be satisfactorily compensated with C filter,producing isolated attosecond pulses with duration of 33 as.According to the wavelength scaling law of high-order harmonic generation,the proposed scheme is of great significance to develop high-flux ultrashort attosecond sources.

Anomalous Thermal Transport across the Superionic Transition in Ice

Superionic ices with highly mobile protons within stable oxygen sub-lattices occupy an important proportion of the phase diagram of ice and widely exist in the interior of icy giants and throughout the Universe.Understanding the thermal transport in superionic ice is vital for the thermal evolution of icy planets.However,it is highly challenging due to the extreme thermodynamic conditions and dynamical nature of protons,beyond the capability of the traditional lattice dynamics and empirical potential molecular dynamics approaches.By utilizing the deep potential molecular dynamics approach,we investigate the thermal conductivity of ice-Ⅶ and superionic ice-Ⅶ’’ along the isobar of P = 30 GPa.A non-monotonic trend of thermal conductivity with elevated temperature is observed.Through heat flux decomposition and trajectory-based spectra analysis,we show that the thermally activated proton diffusion in ice-Ⅶ and superionic ice-Ⅶ′′contribute significantly to heat convection,while the broadening in vibrational energy peaks and significant softening of transverse acoustic branches lead to a reduction in heat conduction.The competition between proton diffusion and phonon scattering results in anomalous thermal transport across the superionic transition in ice.This work unravels the important role of proton diffusion in the thermal transport of high-pressure ice.Our approach provides new insights into modeling the thermal transport and atomistic dynamics in superionic materials.

Optical Tunable MoiréExcitons in Twisted Hexagonal GaTe Bilayers

Optical fine-tunable layer-hybridized Moiréexcitons are highly in demand for emerging many-body states in two-dimensional semiconductors.We report naturally confined layer-hybridized bright Moiréexcitons with long lifetimes in twisted hexagonal GaTe bilayers,using ab initio many-body perturbation theory and the Bethe–Salpeter equation.Due to the hybridization of electrons and holes between layers,which enhances the brightness of excitons,the twisted bilayer system becomes attractive for optical applications.We find that in both R and H-type stacking Moirésuperlattices,more than 200 meV lateral quantum confinements occur on exciton energies,which results in two scenarios:(1)The ground state bright excitons XA are found to be trapped at two high-symmetry points,with opposite electric dipoles in the R-stacking Moirésupercell,forming a honeycomb superlattice of nearest-neighbor dipolar attraction.(2)For H-stacking case,the XA is found to be trapped at only one high-symmetry point exhibiting a triangular superlattice.Our results suggest that twisted h-GaTe bilayer is one of the promising systems for optical fine-tunable excitonic devices and provide an ideal platform for realizing strong correlated Bose–Hubbard physics.

Full-scale ab initio simulations of laser-driven atomistic dynamics

The coupling of excited states and ionic dynamics is the basic and challenging point for the materials response at extreme conditions.In the laboratory,the intense laser produces transient nature and complexity with highly nonequilibrium states,making it extremely difficult and interesting for both experimental measurements and theoretical methods.With the inclusion of laser-excited states,we extend an ab initio method into the direct simulations of whole laser-driven microscopic dynamics from solid to liquid.We construct the framework of combining the electron-temperature-dependent deep neural-network potential energy surface with a hybrid atomistic-continuum approach,controlling non-adiabatic energy exchange and atomistic dynamics,which enables consistent interpretation of experimental data.By large-scale ab initio simulations,we demonstrate that the nonthermal effects introduced by hot electrons play a dominant role in modulating the lattice dynamics,thermodynamic pathway,and structural transformation.We highlight that the present work provides a path to realistic computational studies of laser-driven processes,thus bridging the gap between experiments and simulations.

Efficient terahertz generation from van der Waalsα-In_(2)Se_(3)

Two-dimensional(2D)van der Waals materials have attracted tremendous attention due to their versatile physical properties and flexible manipulation approaches.Among the various types of van der Waals materials,α-In_(2)Se_(3)is remarkable for its intrinsic 2D ferroelectricity and high-performance opto-electronic properties.However,the study of theα-In_(2)Se_(3)system in terahertz(THz)radiation is scarce,although it is promising for electrically controlled THz field manipulation.We investigate theα-In_(2)Se_(3)in different thicknesses and report that the THz generation efficiency induced by femtosecond laser pulses can be largely improved by reducing the thickness from the bulk.Furthermore,we reveal the surge current in thin film coupled with THz emission exhibits a different Auger recombination mode,which is helpful in understanding the mechanism and provides insights into the design of 2D highly efficient THz devices.

Interaction-induced topological transition in spin-orbit coupled ultracold bosons

Recent experiments in ultracold atoms have reported the realization of quantum anomalous Hall phases in spin-orbit coupled systems.Motivated by such advances,we investigate spin-orbit coupled Bose-Bose mixtures in a two-dimensional square optical Raman lattice.Complete phase diagrams are obtained via a nonperturbative real-space bosonic dynamical mean-field theory.Various quantum phases are predicted,including Mott phases with z-ferromagnetic,xy-antiferromagnetic and vortex textures,and superfluid phases with the exotic spin orders,induced by the competition between the lattice hopping and spin-orbit coupling.To explain the underlying physics in the Mott regime,an efective Hamiltonian is derived based on second-order perturbation theory,where pseudospin order stems from the interplay of efective Dzyaloshinskii-Moriya superexchange and Heisenberg interactions.In the presence of the Zeeman field,the competition of strong interaction and Zeeman energy facilitates a topological phase,which is confirmed both by the nontrivial topological Bott index and spectral function with topological edge states.Our work indicates that spin-orbit coupling can induce rich non-Abelian topological physics in strongly correlated ultracold atomic systems.