Applied physics

  • Article
    | Open Access

    The awareness of rock shape dependence in rockfall hazard assessment is growing, but experimental and field studies are scarce. This study presents a large data set of induced single block rockfall events quantifying the influence of rock shape and mass on its complex kinematic behaviour.

    • Andrin Caviezel
    • , Adrian Ringenbach
    •  & Perry Bartelt
  • Article
    | Open Access

    Though non-Hermitian physics has contributed toward the advance of research in quantum, electronic and classical systems, previous work focused on zero- or one-dimensional systems. Here, the authors report higher-order non-Hermitian skin effects in a 2D acoustic higher-order topological insulator.

    • Xiujuan Zhang
    • , Yuan Tian
    •  & Yan-Feng Chen
  • Article
    | Open Access

    Additives have been widely used for passivating defects in perovskite semiconductors, yet the role of additive and their interaction is not clear. Here, the authors reveal an additive-assisted crystal formation in FAPbI3 perovskite by tracking the chemical interaction in the precursor solution and crystallographic evolution using multi-functional additives.

    • Lin Zhu
    • , Hui Cao
    •  & Jianpu Wang
  • Article
    | Open Access

    The authors create synthetic dimensions in acoustic crystals composed of cavity arrays, strongly coupled through modulated channels. They provide evidence for 1D and 2D dynamic topological pumping, and show that the higher-order topological sound transport is robust against the geometrical imperfections.

    • Hui Chen
    • , Hongkuan Zhang
    •  & Guoliang Huang
  • Article
    | Open Access

    Common photovoltaic effect is across the interface of heterojunctions. Here, the authors find that scanning a light beam can induce a persistent in-plane photoelectric voltage along silicon-water interfaces, due to the following movement of a charge packet in the vicinity of the silicon surface.

    • Jidong Li
    • , Yuyang Long
    •  & Jun Yin
  • Article
    | Open Access

    Pulsed operation of perovskite light-emitting diodes is of particular importance in display and visible light communication, yet the ionic behaviour under this mode is not well-understood. Here, the authors reveal that the transient electroluminescence intensity increases with increasing pulse width as the result of accumulation of mobile ions at the interfaces.

    • Naresh Kumar Kumawat
    • , Wolfgang Tress
    •  & Feng Gao
  • Article
    | Open Access

    Though bound states in the continuum (BICs) in acoustic systems are attractive for acoustic resonators design, acoustic BICs typically show low Q-factor. Here, the authors report a high performance open acoustic resonator that supports symmetry-protected, Friedrich-Wintgen and mirror symmetry-induced BICs.

    • Lujun Huang
    • , Yan Kei Chiang
    •  & Andrey E. Miroshnichenko
  • Article
    | Open Access

    Mechanisms of cluster formation in networks with directed links differ from those in undirected networks. Lodi et al. propose a method to compute interdependencies among clusters of nodes in directed networks. They show that clusters can be one-way dependent, as found in social and neural networks.

    • Matteo Lodi
    • , Francesco Sorrentino
    •  & Marco Storace
  • Article
    | Open Access

    Networks describe the intricate patterns of interaction occurring within ecological systems, but they are unfortunately difficult to construct from data. Here, the authors show how Bayesian statistical techniques can separate structure from noise in networks gathered in observational studies of plant-pollinator systems.

    • Jean-Gabriel Young
    • , Fernanda S. Valdovinos
    •  & M. E. J. Newman
  • Article
    | Open Access

    Precise and dynamic manipulation of nano-objects on a large scale has been challenging. Here, the authors introduce acoustoelectronic nanotweezers, combining precision of electronic tweezers with large-field dynamic control of acoustic tweezers, demonstrating complex patterning of sub-100 nm objects.

    • Peiran Zhang
    • , Joseph Rufo
    •  & Tony Jun Huang
  • Article
    | Open Access

    Typically, sending sound from transmitter to receiver requires pre-amplification and disturbs the surrounding sound environment. Here, the authors present a metamaterial designed to enable transmission of weak sound that can be recovered even in the presence of strong noise

    • Jin Zhang
    • , Wei Rui
    •  & Johan Christensen
  • Article
    | Open Access

    Here, the authors introduce a 3D Weyl metamaterial hosting modes bound to a 1D topological lattice defect. The modes carry nonzero orbital angular momentum locked to the direction of propagation, and they experimentally demonstrate the ability to emit acoustic vortices into free space.

    • Qiang Wang
    • , Yong Ge
    •  & Y. D. Chong
  • Article
    | Open Access

    Assessing mechanics of nanoporous silicon is challenging, but important for new applications. Here, the authors use non-destructive laser-excited elastic guided waves detected contactless, to study dry and liquid-infused single-crystalline porous silicon, revealing its complex mechanics and significant deviations from bulk silicon.

    • Marc Thelen
    • , Nicolas Bochud
    •  & Patrick Huber
  • Article
    | Open Access

    This work presents a mechanical metamaterial with 1D array of bistable arches where nonreciprocity and reversibility can be independently programmed. The effects of asymmetry both at the structural and element level on propagation of transition waves are examined.

    • Gabriele Librandi
    • , Eleonora Tubaldi
    •  & Katia Bertoldi
  • Article
    | Open Access

    Here, the authors introduce beyond-nearest-neighbour interactions as a mechanism for molding the flow of waves in acoustic metamaterials. They find that for strong third-nearest-neighbour interactions, this mechanism allows for engineering roton-like acoustical dispersion relations under ambient conditions.

    • Yi Chen
    • , Muamer Kadic
    •  & Martin Wegener
  • Article
    | Open Access

    Inverse design is a recent development in photonics, where by locally controlling the refractive index in a matrix, nearly any information processing functionality can be achieved. Here, Wang et al. present a scheme for inverse design for spin-waves, magnons, which have a variety of unique advantages, such as short wavelength, and large non-linearity.

    • Qi Wang
    • , Andrii V. Chumak
    •  & Philipp Pirro
  • Article
    | Open Access

    Exploiting Willis coupling in acoustic metamaterials with designed geometrical asymmetries opens up new opportunities related to sound control and manipulation. Here, the authors report a dual form of Willis coupling in geometrically symmetric acoustic scatterers.

    • Li Quan
    • , Simon Yves
    •  & Andrea Alù
  • Article
    | Open Access

    Losses, due to their non-Hermitian nature, are generally disregarded or even considered harmful when looking for non-trivial topological phases. Here, the authors experimentally demonstrate that higher-order topology can emerge as a result of introducing losses in an acoustic crystal.

    • He Gao
    • , Haoran Xue
    •  & Baile Zhang
  • Article
    | Open Access

    Integrated photonics are promising to scale up quantum optics. Here the authors combine low-power microelectromechanical control and superconducting single-photon detectors on the same chip and demonstrate routing, high-dynamic-range detection, and power stabilization.

    • Samuel Gyger
    • , Julien Zichi
    •  & Carlos Errando-Herranz
  • Article
    | Open Access

    Conventional optical readout limits the sensitivity of solid state spin sensors due to photon shot noise and poor contrast. Here, the authors demonstrate room-temperature microwave detection of an ensemble of NV centers embedded in a microwave cavity, which offers high-fidelity readout without time overhead.

    • Erik R. Eisenach
    • , John F. Barry
    •  & Danielle A. Braje
  • Article
    | Open Access

    Nanofluidic channels offer the possibility to process small molecules or colloids, but transport control meets serious challenges. Seo et al. use evaporation-driven advective flow to establish a versatile manipulation scheme of the fluid carrier, disposing of external connectors.

    • Sangjin Seo
    • , Dogyeong Ha
    •  & Taesung Kim
  • Article
    | Open Access

    Human-like robotic sensing aims at extracting and processing complicated environmental information via multisensory integration and interaction. Tan et al. report an artificial spiking multisensory neural network that integrates five primary senses and mimics the crossmodal perception of biological brains.

    • Hongwei Tan
    • , Yifan Zhou
    •  & Sebastiaan van Dijken
  • Article
    | Open Access

    Here, a strong nonlinearity of the gate-induced tunnel junction in bilayer graphene is used for efficient terahertz detection. The improved signal-to-noise ratio, as compared to conventional detectors, offers the application of steep-switching transistors in terahertz technology.

    • I. Gayduchenko
    • , S. G. Xu
    •  & D. A. Bandurin
  • Article
    | Open Access

    The authors present a passive meta-neural-network for real-time recognition of objects by analysis of acoustic scattering. It consists of unit cells termed meta-neurons, mimicking an analogous neural network for classical waves, and is shown to recognise handwritten digits and misaligned orbital-angular-momentum vortices.

    • Jingkai Weng
    • , Yujiang Ding
    •  & Jianchun Cheng
  • Article
    | Open Access

    Thermal metamaterials are able to produce unconventional physical properties. Here, the authors demonstrate a thermal metamaterial with conductivity that can be continuously tuned over a very large range.

    • Guoqiang Xu
    • , Kaichen Dong
    •  & Cheng-Wei Qiu
  • Article
    | Open Access

    Antiferromagnets (AFMs) are prospective for future spintronic devices, owing to their speed and insensitivity to perturbations. Using a combination of electronic and magnetic dichroism measurements, the authors demonstrate reversible current-induced switching of the Néel vector in AFM PtMn.

    • Samik DuttaGupta
    • , A. Kurenkov
    •  & H. Ohno
  • Article
    | Open Access

    Typically, phonon trapping is performed using mechanically suspended structures which have many limitations. Here the authors study a phononic structure that supports mechanical bound states in the continuum (BICs) at microwave frequencies with topological features.

    • Hao Tong
    • , Shengyan Liu
    •  & Kejie Fang
  • Article
    | Open Access

    The robust production of droplets by microfluidic T-junctions is a well-established technique. Um et al. demonstrate how the mutual interaction between droplets can be used to achieve additional control including the simultaneous release of droplets caused by synchronization phenomena.

    • Eujin Um
    • , Minjun Kim
    •  & Joonwoo Jeong
  • Article
    | Open Access

    Spin angular momenta play a crucial role in topological phases of matter, in acoustic waves they have been demonstrated recently. Here, the authors present a symmetry-breaking metasurface waveguide that assists backscattering suppression of acoustic waves, because of tight spin-momentum coupling.

    • Yang Long
    • , Danmei Zhang
    •  & Jie Ren
  • Article
    | Open Access

    The development of vertical organic transistors with controllable threshold voltage is highly desirable for integrated circuit-based displays and sensors. Here, the authors report vertical organic permeable dual-based transistors with independently tunable on-currents and threshold voltages.

    • Erjuan Guo
    • , Zhongbin Wu
    •  & Hans Kleemann
  • Article
    | Open Access

    Király et al. propose a method combining micro-CT and MRI imaging to precisely localize electrodes and optic fibers in the mouse brain in vivo. This allows assessing the success of targeting after surgery, depth adjustment of movable probes and identifying systematic errors in the surgical process.

    • Bálint Király
    • , Diána Balázsfi
    •  & Balázs Hangya
  • Article
    | Open Access

    The authors introduce a dynamic spatial ultrasound modulator, based on digitally generated patterns of microbubbles controlled by a complementary metal–oxide–semiconductor (CMOS) chip. They achieve reshaping of incident plane waves into complex acoustic images and demonstrate dynamic parallel assembly of microparticles.

    • Zhichao Ma
    • , Kai Melde
    •  & Peer Fischer
  • Article
    | Open Access

    Acoustical tweezers can exert forces several orders of magnitude greater than optical tweezers but the absence of spatial selectivity and their limited resolution has prevented their use for many applications in microbiology. Here the authors perform spatially selective contactless manipulation and positioning of human cells.

    • Michael Baudoin
    • , Jean-Louis Thomas
    •  & Alexis Vlandas
  • Article
    | Open Access

    Although knots in complex optical fields have been realized experimentally, the realization of acoustic vortex knots is still problematic. Here, the authors have demonstrated the creation of acoustic vortex knots by embedding the knot function into a propagating acoustic field using a metasurface hologram.

    • Hongkuan Zhang
    • , Weixuan Zhang
    •  & Xiangdong Zhang
  • Article
    | Open Access

    Being able to manipulate the temporal evolution and spatial distribution of diffusive quantities would provide exciting possibilities for applications. Here, the authors show that one can achieve large spatial asymmetric diffusion characteristics inside a metamaterial whose material parameters are space- and time-modulated.

    • Miguel Camacho
    • , Brian Edwards
    •  & Nader Engheta
  • Article
    | Open Access

    Here, the authors experimentally demonstrate abilities of a mechanical Willis meta-layer, in beams and plates, for independently engineering transmission and reflection coefficients of flexural waves in both amplitude and phase and nonreciprocal wave propagation.

    • Yangyang Chen
    • , Xiaopeng Li
    •  & Guoliang Huang
  • Article
    | Open Access

    Here, by constructing a heterostructure with sonic crystals, a topological waveguide is realized by the authors. The waveguide states feature gapless dispersion, momentum-valley locking, immunity against defects, and a high capacity for energy transport.

    • Mudi Wang
    • , Wenyi Zhou
    •  & Zhengyou Liu
  • Article
    | Open Access

    Synthetic hair-like structures (cilia) controlled by an external field have been developed, especially for microfluidic applications. Here, Gu et al. make soft artificial cilia carpets with programmable magnetization patterns and utilize them to achieve pumping and locomotion in a soft robotic model.

    • Hongri Gu
    • , Quentin Boehler
    •  & Bradley J. Nelson
  • Article
    | Open Access

    Here, the authors present a light-responsive elastic metamaterial whose transmission spectrum can be tuned by light stimuli. More specifically, we demonstrate that an appropriate laser illumination is effective in reversibly widening an existing frequency band gap, doubling its initial value.

    • Antonio S. Gliozzi
    • , Marco Miniaci
    •  & Emiliano Descrovi

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