One of the most important multipartite entangled states, Greenberger–Horne–Zeilinger state (GHZ), serves as a fundamental resource for quantum foundation test, quantum communication and quantum computation. To increase the number of entangled particles, significant experimental efforts should been invested due to the complexity of optical setup and the difficulty in maintaining the coherence condition for high-fidelity GHZ state. Here, we propose an ultra-integrated scalable on-chip GHZ state generation scheme based on frequency combs. By designing several microrings pumped by different lasers, multiple partially overlapped quantum frequency combs are generated to supply as the basis for on-chip polarization-encoded GHZ state with each qubit occupying a certain spectral mode. Both even and odd numbers of GHZ states can be engineered with constant small number of integrated components and easily scaled up on the same chip by only adjusting one of the pump wavelengths. In addition, we give the on-chip design of projection measurement for characterizing GHZ states and show the reconfigurability of the state. Our proposal is rather simple and feasible within the existing fabrication technologies and we believe it will boost the development of multiphoton technologies.

Lepton scattering is an established ideal tool for studying inner structure of small particles such as nucleons as well as nuclei. As a future high energy nuclear physics project, an Electron-ion collider in China (EicC) has been proposed. It will be constructed based on an upgraded heavy-ion accelerator, High Intensity heavy-ion Accelerator Facility (HIAF) which is currently under construction, together with a new electron ring. The proposed collider will provide highly polarized electrons (with a po- larization of 80%) and protons (with a polarization of 70%) with variable center of mass energies from 15 to 20 GeV and the luminosity of (2–3)×10³³ cm−2•s−1. Polarized deuterons and Helium-3, as well as unpolarized ion beams from Carbon to Uranium, will be also available at the EicC.

The main foci of the EicC will be precision measurements of the structure of the nucleon in the sea quark region, including 3D tomography of nucleon; the partonic structure of nuclei and the parton interaction with the nuclear environment; the exotic states, especially those with heavy flavor quark contents. In addition, issues fundamental to understanding the origin of mass could be addressed by measurements of heavy quarkonia near-threshold production at the EicC. In order to achieve the above-mentioned physics goals, a hermetical detector system will be constructed with cutting-edge technologies.

This document is the result of collective contributions and valuable inputs from experts across the globe. The EicC physics program complements the ongoing scientific programs at the Jefferson Laboratory and the future EIC project in the United States. The success of this project will also advance both nuclear and particle physics as well as accelerator and detector technology in China.

The interlayer bonding in two-dimensional (2D) materials is particularly important because it is not only related to their physical and chemical stability but also affects their mechanical, thermal, electronic, optical, and other properties. To address this issue, we report the direct characterization of the interlayer bonding in 2D SnSe using contact-resonance atomic force microscopy (CR-AFM) in this study. Site-specific CR spectroscopy and CR force spectroscopy measurements are performed on both SnSe and its supporting SiO₂/Si substrate comparatively. Based on the cantilever and contact mechanic models, the contact stiffness and vertical Young’s modulus are evaluated in comparison with SiO₂/Si as a reference material. The interlayer bonding of SnSe is further analyzed in combination with the semi-analytical model and density functional theory calculations. The direct characterization of interlayer interactions using this non-destructive methodology of CR-AFM would facilitate a better understanding of the physical and chemical properties of 2D layered materials, specifically for interlayer intercalation and vertical heterostructures.

Owing to the exceptional properties of graphene, intensive studies have been carried out on novel two-dimensional (2D) materials. In the past several years, an elegant exfoliation approach has been used to successfully create a new family of 2D transition metal carbides, nitrides, and carbonitrides, termed MXene, from layered MAX phases. More recently, some unique properties of MXene have been discovered leading to proposals of potential applications. In this review, we summarize the latest progress in development of MXene from both a theoretical and experimental view, with emphasis on the possible applications.

Since two-dimensional boron sheet (borophene) synthesized on Ag substrates in 2015, research on borophene has grown fast in the fields of condensed matter physics, chemistry, material science, and nanotechnology. Due to the unique physical and chemical properties, borophene has various potential applications. In this review, we summarize the progress on borophene with a particular emphasis on the recent advances. First, we introduce the phases of borophene by experimental synthesis and theoretical predictions. Then, the physical and chemical properties, such as mechanical, thermal, electronic, optical and superconducting properties are summarized. We also discuss in detail the utilization of the borophene for wide ranges of potential application among the alkali metal ion batteries, Li-S batteries, hydrogen storage, supercapacitor, sensor and catalytic in hydrogen evolution, oxygen reduction, oxygen evolution, and CO2 electroreduction reaction. Finally, the challenges and outlooks in this promising field are featured on the basis of its current development.

Copper indium thiophosphate, CuInP₂S₆, has attracted much attention in recent years due to its van der Waals layered structure and robust ferroelectricity at room temperature. In this review, we aim to give an overview of the various properties of CuInP₂S₆, covering structural, ferroelectric, dielectric, piezoelectric and transport properties, as well as its potential applications. We also highlight the remaining questions and possible research directions related to this fascinating material and other compounds of the same family.

Two-dimensional (2D) MoS₂ is used as a catalyst or support and has received increased research interest because of its superior structural and electronic properties compared with those of bulk structures. In this article, we illustrate the active sites of 2D MoS₂ and various strategies for enhancing its intrinsic catalytic activity. The recent advances in the use of 2D MoS₂-based materials for applications such as thermocatalysis, electrocatalysis, and photocatalysis are discussed. We also discuss the future opportunities and challenges for 2D MoS₂-based materials, in both fundamental research and industrial applications.

Topological insulators are emergent states of quantum matter that are gapped in the bulk with timereversal symmetry-preserved gapless edge/surface states, adiabatically distinct from conventional materials. By proximity to various magnets and superconductors, topological insulators show novel physics at the interfaces, which give rise to two new areas named topological spintronics and topological quantum computation. Effects in the former such as the spin torques, spin-charge conversion, topological antiferromagnetic spintronics, and skyrmions realized in topological systems will be addressed. In the latter, a superconducting pairing gap leads to a state that supports Majorana fermions states, which may provide a new path for realizing topological quantum computation. Various signatures of Majorana zero modes/edge mode in topological superconductors will be discussed. The review ends by outlooks and potential applications of topological insulators. Topological superconductors that are fabricated using topological insulators with superconductors have a full pairing gap in the bulk and gapless surface states consisting of Majorana fermions. The theory of topological superconductors is reviewed, in close analogy to the theory of topological insulators.

The rapid development of big-data analytics (BDA), internet of things (IoT) and artificial intelligent Technology (AI) demand outstanding electronic devices and systems with faster processing speed, lower power consumption, and smarter computer architecture. Memristor, as a promising Non-Volatile Memory (NVM) device, can effectively mimic biological synapse, and has been widely studied in recent years. The appearance and development of two-dimensional materials (2D material) accelerate and boost the progress of memristor systems owing to a bunch of the particularity of 2D material compared to conventional transition metal oxides (TMOs), therefore, 2D material-based memristors are called as new-generation intelligent memristors. In this review, the memristive (resistive switching) phenomena and the development of new-generation memristors are demonstrated involving grapheme (GR), transition-metal dichalcogenides (TMDs) and hexagonal boron nitride (h-BN) based memristors. Moreover, the related progress of memristive mechanisms is remarked.

The stabilization and manipulation of laser frequency by means of an external cavity are nearly ubiquitously used in fundamental research and laser applications. While most of the laser light transmits through the cavity, in the presence of some back-scattered light from the cavity to the laser, the self-injection locking effect can take place, which locks the laser emission frequency to the cavity mode of similar frequency. The self-injection locking leads to dramatic reduction of laser linewidth and noise. Using this approach, a common semiconductor laser locked to an ultrahigh-Q microresonator can obtain sub-Hertz linewidth, on par with state-of-the-art fiber lasers. Therefore it paves the way to manufacture high-performance semiconductor lasers with reduced footprint and cost. Moreover, with high laser power, the optical nonlinearity of the microresonator drastically changes the laser dynamics, offering routes for simultaneous pulse and frequency comb generation in the same microresonator. Particularly, integrated photonics technology, enabling components fabricated via semiconductor CMOS process, has brought increasing and extending interest to laser manufacturing using this method. In this article, we present a comprehensive tutorial on analytical and numerical methods of laser self-injection locking, as well a review of most recent theoretical and experimental achievements.

This brief review summarizes recent theoretical and experimental results which predict and establish the existence of quantum droplets (QDs), i.e., robust two- and three-dimensional (2D and 3D) selftrapped states in Bose–Einstein condensates (BECs), which are stabilized by effective self-repulsion induced by quantum fluctuations around the mean-field (MF) states [alias the Lee–Huang–Yang (LHY) effect]. The basic models are presented, taking special care of the dimension crossover, 2D→3D. Recently reported experimental results, which exhibit stable 3D and quasi-2D QDs in binary BECs, with the inter-component attraction slightly exceeding the MF self-repulsion in each component, and in single-component condensates of atoms carrying permanent magnetic moments, are presented in some detail. The summary of theoretical results is focused, chiefly, on 3D and quasi-2D QDs with embedded vorticity, as the possibility to stabilize such states is a remarkable prediction. Stable vortex states are presented both for QDs in free space, and for singular but physically relevant 2D modes pulled to the center by the inverse-square potential, with the quantum collapse suppressed by the LHY effect.

Two-dimensional (2D) materials generally have unusual physical and chemical properties owing to the confined electro-strong interaction in a plane and can exhibit obvious anisotropy and a significant quantum-confinement effect, thus showing great promise in many fields. Some 2D materials, such as graphene and MXenes, have recently exhibited extraordinary electromagnetic-wave shielding and absorbing performance, which is attributed to their special electrical behavior, large specific surface area, and low mass density. Compared with traditional microwave attenuating materials, 2D materials have several obvious inherent advantages. First, similar to other nanomaterials, 2D materials have a very large specific surface area and can provide numerous interfaces for the enhanced interfacial polarization as well as the reflection and scattering of electromagnetic waves. Second, 2D materials have a particular 2D morphology with ultrasmall thickness, which is not only beneficial for the penetration and dissipation of electromagnetic waves through the 2D nanosheets, giving rise to multiple reflections and the dissipation of electromagnetic energy, but is also conducive to the design and fabrication of various well-defined structures, such as layer-by-layer assemblies, core–shell particles, and porous foam, for broadband attenuation of electromagnetic waves. Third, owing to their good processability, 2D materials can be integrated into various multifunctional composites for multimode attenuation of electromagnetic energy. In addition to behaving as microwave reflectors and absorbers, 2D materials can act as impedance regulators and provide structural support for good impedance matching and setup of the optimal structure. Numerous studies indicate that 2D materials are among the most promising microwave attenuation materials. In view of the rapid development and enormous advancement of 2D materials in shielding and absorbing electromagnetic wave, there is a strong need to summarize the recent research results in this field for presenting a comprehensive view and providing helpful suggestions for future development.

Single-atom photocatalysts, due to their high catalysis activity, selectivity and stability, become a hotspot in the field of photocatalysis. Graphitic carbon nitride (g-C₃N₄) is known as both a good support for single atoms and a star photocatalyst. Developing g-C₃N₄-based single-atom photocatalysts exhibits great potential in improving the photocatalytic performance. In this review, we summarize the recent progress in g-C₃N₄-based single-atom photocatalysts, mainly including preparation strategies, characterizations, and their photocatalytic applications. The significant roles of single atoms and catalysis mechanism in g-C₃N₄-based single-atom photocatalysts are analyzed. At last, the challenges and perspectives for exploring high-efficient g-C₃N₄-based single-atom photocatalysts are presented.

Graphene is an ideal 2D material system bridging electronic and photonic devices. It also breaks the fundamental speed and size limits by electronics and photonics, respectively. Graphene offers multiple functions of signal transmission, emission, modulation, and detection in a broad band, high speed, compact size, and low loss. Here, we have a brief view of graphene based functional devices at microwave, terahertz, and optical frequencies. Their fundamental physics and computational models were discussed as well.

This paper proposes a novel bubble model to analyze drag reduction. The relationship between the slip length and air bubble height is discussed. The numerical relationship between the surface contact angle and slip length is obtained using the solid-liquid contact ratio in the Cassie equation. The surface drag reduction ratio increases by 40% at low velocities when the solid liquid contact ratio decreases from 90% to 10%. An experimental setup to study liquid/solid friction drag is reported. The drag reduction ratio for the superhydrophobic surface tested experimentally is 30%–35% at low velocities. These results are similar to the simulation results obtained at low velocities.

This article presents an extensive review of the status of the search of the dark matter. The first eight sections are devoted to topics in dark matter and its experimental searches, and the rest to selected topics in astrophysics and cosmology, which are intended to supply some of the needed background for students in particle physics. Sections 9 and 13 are introductory cosmology. The three astrophysical topics, Big Bang nucleosynthesis Section 10, Boltzmann transport equation and freeze out of massive particles Section 11, and CMB anisotropy Section 12 can all be studied in analytical approaches when reasonable approximations are made. Their original analytically forms, to which this article follows very closely, were given by particle physicists. Dark matter is an evolving subject requiring timely update to stay current. Hence a review of such a subject matter would undoubtedly have something wanting when it appears in print. It is hoped that this review can form a humble basis for those graduate students who would like to pursue the subject of dark matter. The reader can use the extensive table of contents to see in some details the materials covered in the article.

With the development of device engineering and molecular design, organic field effect transistors (OFETs) with high mobility over 10 cm²·V⁻¹·s⁻¹ have been reported. However, the nonideal doubleslope effect has been frequently observed in some of these OFETs, which makes it difficult to extract the intrinsic mobility OFETs accurately, impeding the further application of them. In this review, the origin of the nonideal double-slope effect has been discussed thoroughly, with affecting factors such as contact resistance, charge trapping, disorder effects and coulombic interactions considered. According to these discussions and the understanding of the mechanism behind double-slope effect, several strategies have been proposed to realize ideal OFETs, such as doping, molecular engineering, charge trapping reduction, and contact engineering. After that, some novel devices based on the nonideal double-slope behaviors have been also introduced.

Negative thermal expansion (NTE) of materials is an intriguing phenomenon challenging the concept of traditional lattice dynamics and of importance for a variety of applications. Progresses in this field develop markedly and update continuously our knowledge on the NTE behavior of materials. In this article, we review the most recent understandings on the underlying mechanisms (anharmonic phonon vibration, magnetovolume effect, ferroelectrorestriction and charge transfer) of thermal shrinkage and the development of NTE materials under each mechanism from both the theoretical and experimental aspects. Besides the low frequency optical phonons which are usually accepted as the origins of NTE in framework structures, NTE driven by acoustic phonons and the interplay between anisotropic elasticity and phonons are stressed. Based on the data documented, some problems affecting applications of NTE materials are discussed and strategies for discovering and design novel framework structured NET materials are also presented.

In this review article, we first briefly introduce the transport theory and quantum molecular dynamics model applied in the study of the heavy ion collisions from low to intermediate energies. The developments of improved quantum molecular dynamics model (ImQMD) and ultra-relativistic quantum molecular dynamics model (UrQMD), are reviewed. The reaction mechanism and phenomena related to the fusion, multinucleon transfer, fragmentation, collective flow and particle production are reviewed and discussed within the framework of the two models. The constraints on the isospin asymmetric nuclear equation of state and in-medium nucleon–nucleon cross sections by comparing the heavy ion collision data with transport models calculations in last decades are also discussed, and the uncertainties of these constraints are analyzed as well. Finally, we discuss the future direction of the development of the transport models for improving the understanding of the reaction mechanism, the descriptions of various observables, the constraint on the nuclear equation of state, as well as for the constraint on in-medium nucleon–nucleon cross sections.

We review application of the SU(4) model of strongly-correlated electrons to cuprate and iron-based superconductors. A minimal self-consistent generalization of BCS theory to incorporate antiferromagnetism on an equal footing with pairing and strong Coulomb repulsion is found to account systematically for the major features of high-temperature superconductivity, with microscopic details of the parent compounds entering only parametrically. This provides a systematic procedure to separate essential from peripheral, suggesting that many features exhibited by the high-T_c data set are of interest in their own right but are not central to the superconducting mechanism. More generally, we propose that the surprisingly broad range of conventional and unconventional superconducting and superfluid behavior observed across many fields of physics results from the systematic appearance of similar algebraic structures for the emergent effective Hamiltonians, even though the microscopic Hamiltonians of the corresponding parent states may differ radically from each other.

With the rapid development of topological states in crystals, the study of topological states has been extended to quasicrystals in recent years. In this review, we summarize the recent progress of topological states in quasicrystals, particularly focusing on one-dimensional (1D) and 2D systems. We first give a brief introduction to quasicrystalline structures. Then, we discuss topological phases in 1D quasicrystals where the topological nature is attributed to the synthetic dimensions associated with the quasiperiodic order of quasicrystals. We further present the generalization of various types of crystalline topological states to 2D quasicrystals, where real-space expressions of corresponding topological invariants are introduced due to the lack of translational symmetry in quasicrystals. Finally, since quasicrystals possess forbidden symmetries in crystals such as five-fold and eight-fold rotation, we provide an overview of unique quasicrystalline symmetry-protected topological states without crystalline counterpart.

Chimera states, a symmetry-breaking spatiotemporal pattern in nonlocally coupled identical dynamical units, have been identified in various systems and generalized to coupled nonidentical oscillators. It has been shown that strong heterogeneity in the frequencies of nonidentical oscillators might be harmful to chimera states. In this work, we consider a ring of nonlocally coupled bicomponent phase oscillators in which two types of oscillators are randomly distributed along the ring: some oscillators with natural frequency ω₁ and others with ω₂ . In this model, the heterogeneity in frequency is measured by frequency mismatch |ω₁−ω₂| between the oscillators in these two subpopulations. We report that the nonlocally coupled bicomponent phase oscillators allow for chimera states no matter how large the frequency mismatch is. The bicomponent oscillators are composed of two chimera states, one supported by oscillators with natural frequency ω₁ and the other by oscillators with natural frequency ω₂. The two chimera states in two subpopulations are synchronized at weak frequency mismatch, in which the coherent oscillators in them share similar mean phase velocity, and are desynchronized at large frequency mismatch, in which the coherent oscillators in different subpopulations have distinct mean phase velocities. The synchronization–desynchronization transition between chimera states in these two subpopulations is observed with the increase in the frequency mismatch. The observed phenomena are theoretically analyzed by passing to the continuum limit and using the Ott-Antonsen approach.

Heterostructure is an effective approach in modulating the physical and chemical behavior of materials. Here, the first-principles calculations were carried out to explore the structural, electronic, and carrier mobility properties of Janus MoSSe/GaN heterostructures. This heterostructure exhibits a superior high carrier mobility of 281.28 cm²·V⁻¹·s⁻¹ for electron carrier and 3951.2 cm²·V⁻¹·s⁻¹ for hole carrier. Particularly, the magnitude of the carrier mobility can be further tuned by Janus structure and stacking modes of the heterostructure. It is revealed that the equivalent mass and elastic moduli strongly affect the carrier mobility of the heterostructure, while the deformation potential contributes to the different carrier mobility for electron and hole of the heterostructure. These results suggest that the Janus MoSSe/GaN heterostructures have many potential applications for the unique carrier mobility.

L1₀-FePt distinguishes itself for its ultrahigh perpendicular magnetic anisotropy (PMA), enabling thermally stabile memory cells to scale down to 3 nm. The recently discovered “bulk” spin−orbit torques inL1₀-FePt provide an efficient and scalable way to manipulate the L1₀-FePt magnetization. However, the existence of an external field during the switching limits its practical application, and therefore field-free switching of L1₀-FePt is highly demanded. In this manuscript, by growing the L1₀-FePt film on vicinal MgO (001) substrates, we realize the field-free switching of L1₀-FePt. This method is different from previously established strategies as it does not need to add other functional layers or create asymmetry in the film structure. The dependence on the vicinal angle, film thickness, and growth temperature demonstrates a wide operation window for the field-free switching of L1₀-FePt. We confirm the physical origin of the field-free switching is due to the tilted anisotropy of L1₀-FePt induced by the vicinal surface. We also quantitatively characterize the spin-orbit torques in the L1₀-FePt films. Our results extend beyond the established strategies to realize field-free switching, and potentially could be applied to mass production.

Two-dimensional Janus van der Waals (vdW) heterojunctions, referring to the junction containing at least one Janus material, are found to exhibit tuneable electronic structures, wide light adsorption spectra, controllable contact resistance, and sufficient redox potential due to the intrinsic polarization and unique interlayer coupling. These novel structures and properties are promising for the potential applications in electronics and energy conversion devices. To provide a comprehensive picture about the research progress and guide the following investigations, here we summarize their fundamental properties of different types of two-dimensional Janus vdW heterostructures including electronic structure, interface contact and optical properties, and discuss the potential applications in electronics and energy conversion devices. The further challenges and possible research directions of the novel heterojunctions are discussed at the end of this review.

We extend the idea of laser cooling with adiabatic passage to multi-level type-II transitions. We find the cooling force can be significantly enhanced when a proper magnetic field is applied. That is because the magnetic field decomposes the multi-level system into several two-level sub-systems, hence the stimulated absorption and stimulated emission can occur in order, allowing for the multiple photon momentum transfer. We show that this scheme also works on the laser-coolable molecules with a better cooling effect compared to the conventional Doppler cooling. A reduced dependence on spontaneous emission based on our scheme is observed as well. Our results suggest this scheme is very feasible for laser cooling of polar molecules.

Based on structure prediction method, the machine learning method is used instead of the density functional theory (DFT) method to predict the material properties, thereby accelerating the material search process. In this paper, we established a data set of carbon materials by high-throughput calculation with available carbon structures obtained from the Samara Carbon Allotrope Database. We then trained a machine learning (ML) model that specifically predicts the elastic modulus (bulk modulus, shear modulus, and the Young’s modulus) and confirmed that the accuracy is better than that of AFLOW–ML in predicting the elastic modulus of a carbon allotrope. We further combined our ML model with the CALYPSO code to search for new carbon structures with a high Young’s modulus. A new carbon allotrope not included in the Samara Carbon Allotrope Database, named Cmcm–C24, which exhibits a hardness greater than 80 GPa, was firstly revealed. The Cmcm–C24 phase was identified as a semiconductor with a direct bandgap. The structural stability, elastic modulus, and electronic properties of the new carbon allotrope were systematically studied, and the obtained results demonstrate the feasibility of ML methods accelerating the material search process.

Topological metals (TMs) are a kind of special metallic materials, which feature nontrivial band crossings near the Fermi energy, giving rise to peculiar quasiparticle excitations. TMs can be classified based on the characteristics of these band crossings. For example, according to the dimensionality of the crossing, TMs can be classified into nodal-point, nodal-line, and nodal-surface metals. Another important property is the type of dispersion. According to degree of the tilt of the local dispersion around the crossing, we have type-I and type-II dispersions. This leads to significant distinctions in the physical properties of the materials, owing to their contrasting Fermi surface topologies. In this article, we briefly review the recent advances in this research direction, focusing on the concepts, the physical properties, and the material realizations of the type-II nodal-point and nodal-line TMs.

We review our recent works on the quantum transport, mainly in topological semimetals and also in topological insulators, organized according to the strength of the magnetic field. At weak magnetic fields, we explain the negative magnetoresistance in topological semimetals and topological insulators by using the semiclassical equations of motion with the nontrivial Berry curvature. We show that the negative magnetoresistance can exist without the chiral anomaly. At strong magnetic fields, we establish theories for the quantum oscillations in topological Weyl, Dirac, and nodal-line semimetals. We propose a new mechanism of 3D quantum Hall effect, via the “wormhole” tunneling through the Weyl orbit formed by the Fermi arcs and Weyl nodes in topological semimetals. In the quantum limit at extremely strong magnetic fields, we find that an unexpected Hall resistance reversal can be understood in terms of the Weyl fermion annihilation. Additionally, in parallel magnetic fields, longitudinal resistance dips in the quantum limit can serve as signatures for topological insulators.

Laser-induced breakdown spectroscopy (LIBS) has been widely studied due to its unique advantages such as remote sensing, real-time multi-elemental detection and none-to-little damage. With the efforts of researchers around the world, LIBS has been developed by leaps and bounds. Moreover, in recent years, more and more Chinese LIBS researchers have put tremendous energy in promoting LIBS applications. It is worth mentioning that the application of LIBS in a specific field has its special application background and technical difficulties, therefore it may develop in different stages. A review summarizing the current development status of LIBS in various fields would be helpful for the development of LIBS technology as well as its applications especially for Chinese LIBS community since most of the researchers in this field work in application. In the present work, we summarized the research status and latest progress of main research groups in coal, metallurgy, and water, etc. Based on the current research status, the challenges and opportunities of LIBS were evaluated, and suggestions were made to further promote LIBS applications.