An automatic computer method for deriving the intensities, widths, and positions from experimental x-ray diffraction and energy spectroscopy data is outlined. Complex overlapping clusters of peaks can be resolved and the data are corrected for aberrations.

Realization of electromagnetic energy confinement beyond the diffraction limit is crucial for high-performance on-chip devices. Herein we construct an array of nonradiative anapoles that originate from the destructive far-field interference of electric and toroidal dipole modes to achieve ultracompact and high-efficiency electromagnetic energy transfer without the coupler. We experimentally investigate the proposed metachain at mid-infrared frequencies and give the first near-field experimental evidence of anapole-based energy transfer, in which the spatial profile of the anapole mode is also unambiguously identified on the nanoscale. We further demonstrate that the metachain is intrinsically lossless and scalable at infrared wavelengths, realizing a 90°bending loss down to 0.32 dB at the optical communication wavelength. The present scheme bridges the gap between the energy confinement and the transfer of anapoles and opens a new gate for more compactly integrated photonic and energy devices, which can operate in a broad spectral range.

The capability of quality-of-service (QoS) provisioning is of particular importance for multi-hop wireless networks when the real-time applications boost in current days. The scheduling and delivery of data packets in a deficient method may probably cause network congestion, which will in turn decrease the capability of QoS provisioning in the network. To this end, we propose a joint QoS provisioning and congestion control scheme for multi-hop wireless network in this paper based on our previous works of Differentiated Queueing Service (DQS) and Semi-TCP, which provide per-packet granular QoS and carry out efficient hop-by-hop congestion control, respectively. While DQS and Semi-TCP are studied separately, we investigate the arising issues in the joint scheme and propose possible solutions accordingly, including a fast estimation of the latest departure time, a method to handle overdue packets, and an adaptive ACK scheme, as well as the design of a shared database cross-layer architecture for the implementation in the protocol stack. Simulation results show that our proposal improves the network performance in terms of goodput, delivery ratio, and end-to-end delay significantly, particularly in the scenario of mobile users. Our discussion and simulation results both indicate that the proposed joint scheme is flexible and adaptive to the dynamic multi-hop wireless network environment.

Engineering light-matter interaction using cold atomic arrays is one of the central topics in modern optics. Here we have demonstrated the capability of two-dimensional asymmetric cold atomic arrays as microscopic metasurfaces for controlling polarization states of light. The designed linear polarizer can lead to an extinction ratio over 20dB as well as a high transmittance over 0.8 for the permitted polarization at zero detuning. For detuned driving light, changing lattice constants can also achieve high performance linear polarizers. We have also accomplished a circular polarizer by manipulating the phases of transmitted light. A theoretical analysis based on Bloch theorem shows the underlying mechanism for this performance is actually attributed to cooperative effects in periodic lattices. Finally, we discuss in detail the effects of system size, lattice imperfection and nonzero driving light linewidth in practical implementation. The present study paves a way to design extremely miniaturized metasurfaces using cold atoms and other two-level systems, showing great potential in quantum information and quantum metrology sciences as well as the fundamental physics of light-matter interaction.