The High Energy Photon Source (HEPS) is the first fourth-generation synchrotron radiation light source project in Asia, with an electron energy of 6 GeV, a circumference of 1360 m and a natural emittance of a few tens of picometers. As a green-field light source, the HEPS construction started in 2019 and is scheduled to be completed in 2025. Now civil construction, component fabrication and tunnel installation have been complected, and multipole milestones have been achieved in commissioning of the accelerator and beamlines. In this review paper, the design as well as the commissioning progress of the HEPS accelerator and beamlines are reported, where the challenges faced and corresponding measures during the design and commissioning are introduced.

Abstract We employ cluster extension of dynamical mean-field theory (CDMFT) to systematically investigate the impact of double counting corrections on the correlated electronic structure of La 3 Ni 2 O 7 under ambient pressure. By adjusting double-counting parameters, while maintaining a fixed Fermi surface, we observe a pronounced orbital-selective density of states change: the $$d_{z^2}$$ d z 2 orbital undergoes significant variation near the Fermi level with increasing $$E_{dc}^z$$ E dc z , while the $$d_{x^2-y^2}$$ d x 2 - y 2 orbital remains essentially unchanged throughout the entire range. Analysis of renormalization factor show the monotonic dependence with double counting in both $$d_{z^2}$$ d z 2 and $$d_{x^2-y^2}$$ d x 2 - y 2 orbital, and it also identifies an optimal double counting window in $$d_{z^2}$$ d z 2 orbital aligns with experimental values. We also find the interlayer Matsubara self energy exhibits non-monotonic dependence on $$E_{dc}^z$$ E dc z , deviating from theoretical predictions. This anomaly is attributed to the metallization of oxygen-bridged pathways, which disrupts the prerequisite for charge transfer via apical oxygen. Our results establish $$E_{dc}$$ E dc as a critical control parameter for correlated electronic structure in La 3 Ni 2 O 7 and provide a computational framework for resolving orbital-dependent correlation effects in layered materials.

Abstract Indirect-drive double-shell implosions have been performed at 100 kJ laser facility in China. The system of differential equations for the unablated mass, the average implosion velocity, and the ablation front radius of an outer shell within an indirect-drive double-shell capsule during acceleraction and deceleraction phases has been proposed from conservation principles of hydrodynamics. In addition, corrected rocket model for the inner shell has been built; the radius and velocity of the outer surface of the inner shell, as well as the radius and velocity of the inner shell mass center, are solved and give simple expressions. These relations provide the maximum implosion velocity and remaining unablated mass in terms of the initial capsule and the radiation temperature. These results are compared with numerical simulations, and good agreements have been observed.

Abstract By using both diagrammatic theory and Chevy ansatz approach, we derive an exact set of equations, which determines the spectral function of Fermi polarons with multiple particle-hole excitations at nonzero temperature. In the diagrammatic theory, we find out the complete series of Feynman diagrams for the multi-particle vertex functions, when the unregularized contact interaction strength becomes infinitesimal, a typical situation occurring in two- or three-dimensional free space. The latter Chevy ansatz approach is more widely applicable, allowing a nonzero interaction strength. We clarify the equivalence of the two approaches for an infinitesimal interaction strength and show that the variational coefficients in the Chevy ansatz are precisely the on-shell multi-particle vertex functions divided by an excitation energy. Truncated to a particular order of particle-hole excitations, the set of equations can be used to approximately calculate the finite-temperature polaron spectral function, once the numerical singularities in the equations are appropriately treated. As a concrete example, we calculate the finite-temperature spectral function of Fermi polarons in one-dimensional lattices, taking into account all the two-particle-hole excitations. We show that the inclusion of two-particle-hole excitations quantitatively improve the predictions on the polaron spectral function. Our results provide a useful way to solve the challenge problem of accurately predicting the finite-temperature spectral function of Fermi polarons in three-dimensional free space. In addition, our clarification of the complete set of Feynman diagrams for the multi-particle polaron vertex functions may inspire the development of more accurate diagrammatic theories of population-imbalanced strongly interacting Fermi gases, beyond the conventional many-body T-matrix approximation.

As two-dimensional (2D) semiconductor devices demand ever higher performance and tunable photo-energy responses, the ability to probe and control exciton-trion interconversion has attracted much attention. However, conventional optical studies predominantly rely on far-field schemes, which suffer from inherent limitations, such as low spatial resolution and weak photoluminescence signals, restricting practical applications. To address these challenges, plasmonic structures have been employed to enhance local electromagnetic fields, facilitating more efficient exciton-trion interconversion in 2D transition metal dichalcogenides. Furthermore, tip-enhanced approaches have expanded the frontiers of excitontrion study by enabling nanoscale spatial resolution and various modulation capabilities, under active cavity configuration. This review article addresses the critical challenge of probing and controlling exciton-trion interconversion. It provides a comprehensive overview of current techniques, spanning far field spectroscopy, plasmonic enhancement, and tip based methodologies, including both foundational strategies and emerging advanced modulation schemes. By summarizing recent developments in this field, this work aims to outline future directions for harnessing photonic quasi particles to advance next-generation optoelectronic and quantum technologies.

To satisfy the needs of modern intelligent society for power supplies with long-endurance ability, Li-rich Mn-based layered oxides (LRMOs) are receiving much attention because of their ultrahigh capacity. However, their real-world implementation is hindered by the serious voltage decay, which results in a continuous decrease in energy density. The understanding on voltage decay still remains a mystery due to the complicated hybrid cationic-anionic redox and the serious surface-interface reactions in LRMOs. Moreover, some of the mechanisms are occasionally contradictory, indicating that the origin of voltage decay is still unclear. As a result, none of the innovative strategies proposed on the basis of mechanisms has effectively alleviated the problem of voltage decay, and voltage decay becomes a long-term distress of LRMOs. Therefore, it is particularly crucial to sort out the mutual relation of various mechanisms, which helps to go back to the source of voltage decay. In this review, we summarize the current mechanisms of voltage decay as structural evolution and oxygen chemistry, and attempt to trace the origin of voltage decay for LRMOs. In addition, we discuss how current researches address the issue with generalized guidance in designing appropriate strategies based on mechanisms.

Polaron, a typical quasi-particle that describes a single impurity dressed with surrounding environment, serves as an ideal platform for bridging few- and many-body physics. In particular, different few-body correlations can compete with each other and lead to many intriguing phenomena. In this work, we review the recent progresses made in understanding few-body correlation effects in attractive Fermi polarons of ultracold gases. By adopting a unified variational ansatz that incorporates different few-body correlations in a single framework, we will discuss their competing effects in Fermi polarons when the impurity and majority fermions have the same or different masses. For the equal-mass case, we review the nature of polaron-molecule transition that is driven by two-body correlations, and especially highlight the finite momentum character and huge degeneracy of molecule states. For the mass-imbalanced case, we focus on the smooth crossover between polaron and various dressed clusters that originate from high-order correlations. These competing few-body correlations reviewed in Fermi polarons suggest a variety of exotic new phases in the corresponding many-body system of Fermi-Fermi mixtures.

Graphitic carbon nitride (g-CN), as a potential photoelectrode for photoelectrochemical water splitting, has garnered significant research attention owing to its favorable attributes, including a suitable bandgap, abundant elemental composition, excellent thermal stability, and non-toxicity. However, the limited efficiency of visible light absorption and poor electrical conductivity of pure g-CN result in low photocurrent density and photocatalytic activity, falling short of meeting the requirements for commercial applications. In contrast, graphitic carbon materials possess high conductivity and stability, appearing to be an excellent candidate for enhancing the photocatalytic performance of g-CN while maintaining its stability. Recently, nitrogen vacancies, surface junction, carbon crystallite introduction, and carbon atom doping methods have been employed to prepare carbon-modified g-CN. The introduced π-electron conjugated system by sp2-hybridized carbon atoms indeed extends the visible light absorption and photocurrent of g-CN, resulting in improved photocatalytic performance. In this review, we highlight recent advancements in the development of carbon-modified g-CN and offer insights into the future prospects of g-CN-based films.