Reports on progress in physics. Physical Society (Great Britain)最新文献

Two-dimensional (2D) material (graphene, MoS₂, WSe₂, MXene,etc)/group-III nitride (GaN, AlN, and their compounds) hetero-structures have been given special attention, on account of their prospective applications in remarkable performance broadband photodetectors, light-emitting diodes, solar cells, memristors, hydrogen sensors,etc. The utilization of advantages of the above two kind materials provides a solution to the dilemma of the degradation of device performance and reliability caused by carrier mobility, contact resistance, lattice mismatch, interface, and other factors. Therefore, the summary of the recent progress of 2D material/group-III nitride hetero-structures is urgent. In this work, it elaborates on interface interaction and stimulation, growth mechanism and device physic of 2D material/group-III nitride hetero-structures. Initially, it investigates the properties of the hetero-structures, combining the theoretical calculations on interface interaction of the heterojunction with experimental study, particularly emphasizing on interface effects on the performance of hetero-materials. The structure modification (band alignments, band edge position, synergetic work function and so on) at interface contributes to the outstanding properties of these hetero-structures. Subsequently, the growth of 2D material/group-III nitride hetero-structures is introduced in detail. The problems solved by the advancing synthesis strategies and the corresponding formation mechanisms are discussed in particular. Afterwards, based on the 2D material/group-III nitride hetero-structures, extending from optoelectronics, electronics, to photocatalyst and sensors,etc, are reviewed. Finally, the prospect of 2D material/group-III nitride hetero-structures is speculated to pave the way for further promotion.

Amidst the escalating environmental concerns driven by global warming and the detrimental impacts of extreme climates, energy consumption and greenhouse gas emissions associated with refrigeration have reached unprecedented levels. Radiative cooling, as an emerging renewable cooling technology, has been positioned as a pivotal strategy in the fight against global warming. This review examines the theoretical model of radiative cooling emitters and complex practical environment. We first investigate the thermodynamic interactions between environmental factors and the cooling surface, followed by an examination of innovative modulation techniques such as asymmetric/non-reciprocal radiative heat transfer mechanisms. Additionally, we summarize the latest advancements in structural design and simulation methodologies for radiative cooling materials at the device level. We then delve into potential applications of radiative cooling materials in various scenarios including energy-efficient construction, personal thermal management, photovoltaic cooling, and dynamic PDRC materials with seasonal adaptability. In conclusion, we provide a comprehensive overview of this technology's strengths and current challenges to inspire further research and application development in radiative cooling technology with a focus on contributing towards energy conservation objectives and promoting a sustainable society.

We develop a systematic perturbative framework to engineer an arbitrary target Hamiltonian in the Floquet phase space of a periodically driven oscillator based on Floquet-Magnus expansion. The high-order errors in the engineered Floquet Hamiltonian are mitigated by adding high-order driving potentials perturbatively. We introduce a transformation method that allows us to obtain an analytical expression of the leading-order correction drive for engineering a target Hamiltonian with discrete rotational and chiral symmetries in phase space. We also provide a numerically efficient procedure to calculate high-order correction drives and apply it to engineer the target Hamiltonian with degenerate eigenstates of multi-component cat states that are important for fault-tolerant hardware-efficiency bosonic quantum computation.

Liquid-liquid crystalline phase separation (LLCPS) is the process by which an initially homogenous single-phase solution composed of a solvent-most frequently water- and a solute-typically rigid or semiflexible macromolecules, polymers, supramolecular aggregates, or filamentous colloids-demixes into two (or more) distinct phases in which one phase is depleted by the solute and features properties of isotropic solutions, whereas the other is enriched by the solute and exhibits liquid crystalline anisotropic properties. Differently from the more common liquid-liquid phase separation (LLPS) of flexible macromolecules, which is a trade-off between entropy and enthalpy, LLCPS is mostly an entropy-controlled process in which the morphology, composition and properties of the new phases depend primarily on kinetics and thermodynamic factors and, unexpectedly, on the history followed to reach a specific point in the phase diagram. This review aims to comprehensively discuss the process of LLCPS from experimental, theoretical, and simulation standpoints. We discuss the main systems and experimental approaches followed over the past decades to induce and control LLCPS, then we delve into the main theoretical and modeling approaches available to rationalize this process, and finally, we expand on how numerical simulations can significantly enrich the understanding of LLCPS. A final section touches on possible applications and the significance of LLCPS beyond pure physics, that is, in the broader context of biology, nanotechnology, and everyday life.

The fill factor (FF) is a critical parameter for solar cell efficiency, but its analytical description is challenging due to the interplay between recombination and charge extraction processes. A significant factor contributing toFFlosses, beyond recombination, that has not received much attention is the influence of charge transport. In most state-of-the-art organic solar cells, the primary limitations of theFFdo not just arise from non-radiative recombination, but also from low conductivity of the organic semiconductors. A closer look reveals that even in the highest efficiency cells, performance losses due to transport resistance are significant. This finding highlights the need for refined models to predict theFFaccurately. Here, we extend the analytical model for transport resistance to a more general case by incorporating energetic disorder. We introduce a straightforward set of equations to predict theFFof a solar cell, enabling the differentiation of losses attributed to recombination and transport resistance. Our analytical model is validated with a large set of experimental current-voltage and light intensity-dependent open-circuit voltage data for a wide range of temperatures. Based on our findings, we provide valuable insights into strategies for mitigatingFFlosses, guiding the development of more efficient solar cell designs and optimisation strategies.

We review recent progress regarding the double scaled Sachdev-Ye-Kitaev model and otherp-local quantum mechanical random Hamiltonians. These models exhibit an expansion using chord diagrams, which can be solved by combinatorial methods. We describe exact results in these models, including their spectrum, correlation functions, and Lyapunov exponent. In a certain limit, these techniques manifest the relation to the Schwarzian quantum mechanics, a theory of quantum gravity inAdS₂. More generally, the theory is controlled by a rigid algebraic structure of a quantum group, suggesting a theory of quantum gravity on non-commutativeq-deformedAdS₂. We conclude with discussion of related universality classes, and survey some of the current research directions.

The smoothed particle hydrodynamics (SPH) method is expanding and is being applied to more and more fields, particularly in engineering. The majority of current SPH developments deal with free-surface and multiphase flows, especially for situations where geometrically complex interface configurations are involved. The present review article covers the last 25 years of development of the method to simulate such flows, discussing the related specific features of the method. A path is drawn to link the milestone articles on the topic, and the main related theoretical and numerical issues are investigated. In particular, several SPH schemes have been derived over the years, based on different assumptions. The main ones are presented and discussed in this review underlining the different contexts and the ways in which they were derived, resulting in similarities and differences. In addition, a summary is provided of the recent corrections proposed to increase the accuracy, stability and robustness of SPH schemes in the context of free-surface and multiphase flows. Future perspectives of development are identified, placing the method within the panorama of Computational Fluid Dynamics.

Irradiation of condensed matter with ionizing radiation generally causes direct photoionization as well as secondary processes that often dominate the ionization dynamics. Here, large helium (He) nanodroplets with radius≳40nm doped with lithium (Li) atoms are irradiated with extreme ultraviolet (XUV) photons of energyhν⩾44.4 eV and indirect ionization of the Li dopants is observed in addition to direct photoionization of the He droplets. Specifically, Li ions are efficiently produced by an interatomic Coulombic decay (ICD) process involving metastable He∗atoms and He2∗excimers which are populated by elastic and inelastic scattering of photoelectrons in the nanodroplets as well as by electron-ion recombination. This type of indirect ICD, observed in large He nanodroplets in nearly the entire XUV range, turns out to be more efficient than Li dopant ionization by ICD following direct resonant photoexcitation athν=21.6eV and by charge-transfer ionization. Indirect ICD processes induced by scattering of photoelectrons likely play an important role in other condensed phase systems exposed to ionizing radiation as well, including biological matter.

A search for light long-lived particles (LLPs) decaying to displaced jets is presented, using a data sample of proton-proton collisions at a center-of-mass energy of 13.6 TeV, corresponding to an integrated luminosity of 34.7 fb^-1, collected with the CMS detector at the CERN LHC in 2022. Novel trigger, reconstruction, and machine-learning techniques were developed for and employed in this search. After all selections, the observations are consistent with the background predictions. Limits are presented on the branching fraction of the Higgs boson to LLPs that subsequently decay to quark pairs or tau lepton pairs. An improvement by up to a factor of 10 is achieved over previous limits for models with LLP masses smaller than 60 GeV and proper decay lengths smaller than 1 m. The first constraints are placed on the fraternal twin Higgs (FTH) and folded supersymmetry (FSUSY) models, where the lower bounds on the top quark partner mass reach up to 350 GeV for the FTH model and 250 GeV for the FSUSY model.