Taking the temperature of hot electrons: As electronic chips become smaller, efficient heat dissipation becomes a greater challenge. Electrons in such devices quickly accelerate over small distances, becoming “hot”—that is, out of equilibrium with the rest of the system. Weng et al. designed a thermometry probe that measures the effective temperature of hot electrons with a spatial resolution of about 50 nanometers. The method is based on the optical measurement of current noise and provides a glimpse into where heat is naturally dissipated in a working device. Science , this issue p. 775

A triple-band perfect plasmonic metamaterial absorber based on a metal/insulator/metal (MIM) structure is designed. A new freedom through tuning the thicknesses of each ring structures is introduced to realize a quasi-three-dimensional perfect absorber at three extinction wavelengths by using the finite difference time domain method. The physical machine is explained by the time domain field analyses and the coupled mode theory. The characteristics of the absorber make our proposed strategy applicable for the design of more general multiband and broadband perfect absorbers. In addition, these perfect absorbing metamaterials are found to exhibit excellent performance in refractive index sensing.

Broken symmetries play a fundamental role in superconductivity and influence many of its properties in a profound way. Understanding these symmetry breaking states is essential to elucidate the various exotic quantum behaviors in non-trivial superconductors. Here, we report an experimental observation of spontaneous rotational symmetry breaking of superconductivity at the heterointerface of amorphous (a)-YAlO₃/KTaO₃(111) with a superconducting transition temperature of 1.86 K. Both the magnetoresistance and superconducting critical field in an in-plane field manifest striking twofold symmetric oscillations deep inside the superconducting state, whereas the anisotropy vanishes in the normal state, demonstrating that it is an intrinsic property of the superconducting phase. We attribute this behavior to the mixed-parity superconducting state, which is an admixture of s-wave and p-wave pairing components induced by strong spin-orbit coupling inherent to inversion symmetry breaking at the heterointerface of a-YAlO₃/KTaO₃. Our work suggests an unconventional nature of the underlying pairing interaction in the KTaO₃ heterointerface superconductors, and brings a new broad of perspective on understanding non-trivial superconducting properties at the artificial heterointerfaces.

Recent works in metamaterials and transformation optics have demonstrated exotic properties in a number of open systems, including perfect absorption/transmission, electromagnetically induced transparency, cloaking or invisibility, etc. Meanwhile, non-Hermitian physics framework has been developed to describe the properties of open systems, however, most works related to this focus on the eigenstate properties with less attention paid to the reflection characteristics in complex frequency plane, despite the usefulness of zero-reflection (ZR) for applications. Here we demonstrate that the indirectly coupled two-magnon system not only exhibits non-Hermitian eigenmode hybridization, but also ZR states in complex frequency plane. The observed perfect-ZR (PZR) state, i.e., ZR with pure real frequency, is manifested as infinitely narrow reflection dips (~67 dB) with infinite group delay discontinuity. This reflection singularity of PZR distinguishes from the resonant eigenstates but can be adjusted on or off resonance with the eigenstates. Accordingly, the absorption and transmission can be flexibly tuned from nearly full absorption (NFA) to nearly full transmission (NFT) regions.

Uncooled infrared detection based on vanadium dioxide (VO ₂ ) radiometer is highly demanded in temperature monitoring and security protection. The key to its breakthrough is to fabricate bolometer arrays with great absorbance and excellent thermal insulation using a straightforward procedure. Here, we show a tubular bolometer by one-step rolling VO ₂ nanomembranes with enhanced infrared detection. The tubular geometry enhances the thermal insulation, light absorption, and temperature sensitivity of freestanding VO ₂ nanomembranes. This tubular VO ₂ bolometer exhibits a detectivity of ~2 × 10 ⁸ cm Hz ^1/2 W ⁻¹ in the ultrabroad infrared spectrum, a response time of ~2.0 ms, and a calculated noise-equivalent temperature difference of 64.5 mK. Furthermore, our device presents a workable structural paradigm for polarization-sensitive and omnidirectional light coupling bolometers. The demonstrated overall characteristics suggest that tubular bolometers have the potential to narrow performance and cost gap between photon detectors and thermal detectors with low cost and broad applications.