Newsfeeds

Reports on Progress in Physics - latest papers

Latest articles for Reports on Progress in Physics

IOPscience

  • Abrikosov clusters in chiral liquid crystal droplets
    Self-organizing triangular lattices of topological vortices have been observed in type-II superconductors, Bose–Einstein condensates, and chiral magnets under external forcing. Liquid crystals exhibit vortex self-organization in dissipative media. In this study, we experimentally investigate the formation of vortex clusters, analogous to Abrikosov lattices, in temperature-driven chiral liquid crystal droplets. Based on a Ginzburg–Landau-like equation, we derive the interaction laws underlying the formation of these Abrikosov clusters of chiral domains. The origin of these is elucidated due to the competition between the repulsive interaction and the spatial effect of the confinement within the droplet. Our results advance the theoretical understanding of localized vortex self-organization in liquid crystals and open up possibilities for controlling the clustering of these topological defects.

  • The rigid unit mode model: review of ideas and applications
    We review a set of ideas concerning the flexibility of network materials, broadly defined as structures in which atoms form small polyhedral units that are connected at corners. One clear example is represented by the family of silica polymorphs, with structures composed of corner-linked SiO4 tetrahedra. The rigid unit mode (RUM) is defined as any normal mode in which the structural polyhedra can translate and/or rotate without distortion, and since forces associated with changing the size and shape of the polyhedra are much stronger than those associated with rotations of two polyhedra around a shared vertex, the RUMs might be expected to have low frequencies compared to all other phonon modes. In this paper we discuss the flexibility of network structures, and how RUMs can arise in such structures, both in principle and in a number of specific examples of real systems. We also discuss applications of the RUM model, particularly for our understanding of phenomena such as displacive phase transitions and negative thermal expansion in network materials.

  • Interatomic and intermolecular decay processes in quantum fluid clusters
    In this comprehensive review, we explore interatomic and intermolecular correlated electronic decay phenomena observed in superfluid helium nanodroplets subjected to extreme ultraviolet radiation. Helium nanodroplets, known for their distinctive electronic and quantum fluid properties, provide an ideal environment for examining a variety of non-local electronic decay processes involving the transfer of energy, charge, or both between neighboring sites and resulting in ionization and the emission of low-kinetic energy electrons. Key processes include interatomic or intermolecular Coulombic decay and its variants, such as electron transfer-mediated decay. Insights gained from studying these light-matter interactions in helium nanodroplets enhance our understanding of the effects of ionizing radiation on other condensed-phase systems, including biological matter. We also emphasize the advanced experimental and computational techniques that make it possible to resolve electronic decay processes with high spectral and temporal precision. Utilizing ultrashort pulses from free-electron lasers, the temporal evolution of these processes can be followed, significantly advancing our comprehension of the dynamics within quantum fluid clusters and non-local electronic interactions in nanoscale systems.

  • Superscattering of light: fundamentals and applications
    Superscattering, theoretically predicted in 2010 and experimentally observed in 2019, is an exotic scattering phenomenon of light from subwavelength nanostructures. In principle, superscattering allows for an arbitrarily large total scattering cross section, due to the degenerate resonance of eigenmodes or channels. Consequently, the total scattering cross section of a superscatterer can be significantly enhanced, far exceeding the so-called single-channel limit. Superscattering offers a unique avenue for enhancing light–matter interactions and can enable numerous practical applications, ranging from sensing, light trapping, bioimaging, and communications to optoelectronics. This paper provides a comprehensive review of the recent progress and developments in the superscattering of light, with a specific focus on elucidating its theoretical origins, experimental observations, and manipulations. Moreover, we offer an outlook on future research directions in superscattering, including potential realizations of directional superscattering, scattering-free plasmonic superscattering, enhancement of free-electron radiation and the Purcell effect via superscatterers, inelastic superscattering, and superscattering of non-electromagnetic waves.

  • Key issues review: useful autonomous quantum machines
    Controlled quantum machines have matured significantly. A natural next step is to increasingly grant them autonomy, freeing them from time-dependent external control. For example, autonomy could pare down the classical control wires that heat and decohere quantum circuits; and an autonomous quantum refrigerator recently reset a superconducting qubit to near its ground state, as is necessary before a computation. Which fundamental conditions are necessary for realizing useful autonomous quantum machines? Inspired by recent quantum thermodynamics and chemistry, we posit conditions analogous to DiVincenzo’s criteria for quantum computing. Furthermore, we illustrate the criteria with multiple autonomous quantum machines (refrigerators, circuits, clocks, etc) and multiple candidate platforms (neutral atoms, molecules, superconducting qubits, etc). Our criteria are intended to foment and guide the development of useful autonomous quantum machines.