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The time it takes for a particle to tunnel through a potential barrier, and even the interpretation of this phenomenon, have long drawn debate. By performing an attosecond angular streaking experiment in connection with ab initio calculations, researchers have concluded that tunnelling is instantaneous for atomic hydrogen.
Emerging data reveal that amyloid fibrils possess intrinsic photonic activity, showing luminescence over a wide range of the electromagnetic spectrum from the ultraviolet to the near-infrared.
The combined technique of dual-comb multi-heterodyne detection and Fourier-transform analysis allows simultaneous acquisition and monitoring of the phase pattern of a generic frequency comb demonstrating the high degree of coherence of the emission of two quantum cascade laser frequency combs.
By using a single-quantum-well active region with a unique well–cladding design to suppress non-radiative recombination and enhance radiative recombination, light-emitting diodes with close to unity internal quantum efficiency at a low current density of <10−4 A cm−2 are demonstrated.
A method to control the polarization of a Compton gamma-ray beam is developed. By using a free-electron laser oscillator with two helical undulator magnets of opposite helicities, Compton gamma-ray beams with a polarizability of 0.97 are generated.
Perovskite-like materials enable different X-ray detection performance along different crystal directions. A low detection limit of 55 nGyair s−1 is demonstrated.
The polarization structure around polarization singularities can exhibit arbitrary fractional rotations when tracing around the singularity, due to an underlying topology of a torus knot imprinted by the chosen ratio of frequencies contained in the light beam.
A two-step sequential broadband nanofocusing technique offers an external efficiency of ~50% over nearly all the visible range on a fibre-coupled plasmonic nanowire probe. Its integration with a scanning tunnelling microscope realizes lens-free tip-enhanced Raman spectroscopy with 1 nm spatial resolution.
Femtosecond laser pulses can generate self-organized nonlinear gratings in nanophotonic waveguides, providing both quasi-phase-matching and group-velocity matching for second-harmonic generation, and enabling simultaneous χ2 and χ3 nonlinear processes for laser-frequency-comb stabilization.