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Light-matter interactions are generally dominated by electric fields and electric-dipole transitions. This study, however, quantifies magnetic contributions to light emission and so exploits the strong natural magnetic-dipole transitions in lanthanide ions to measure optical-frequency magnetic fields.

Marrying the single-molecule detection ability of surface-enhanced Raman scattering with the extreme time resolution of ultrafast coherent spectroscopy enables the vibrations of a single molecule to be observed.

Here, the authors investigate the intrinsic ultrafast transport dynamics in mono- and multi-layered MoSe₂ by studying suspended crystals that do not suffer from detrimental substrate effects. They identify four sequential transport regimes, including a phase of negative diffusion and slow exciton propagation.

Frequency-resolved transient excited-state absorption of a single molecule is measured at room temperature. The dynamic Stokes shift and vibrational cooling are directly measured with 25 fs temporal resolution and a spectral detection bandwidth of hundreds of meV.

Single-molecule techniques and femtosecond pulse shaping are now combined to investigate quantum coherence in biomolecules. The creation and manipulation of such coherence enables a basic single-qubit operation with terrylene diimide at room temperature.

Confinement of light in subnanometre gaps encounters a fundamental limit in the quantum tunnelling regime.

Diffraction places a fundamental limit on the smallest scales at which light can be controlled. A nanoscale silver array not only circumvents the barrier, but steers different-coloured light to different places.

Changing the polarization of tightly focused light could be important for future high-resolution imaging and data-storage applications. Researchers have now shown that a simple lens can do the task without the need for polarizers.

Subwavelength holes in metal films are well known to offer extraordinary-light-transmission properties. Now a group of scientists in France have exploited such nanoholes to sort photons by colour.

A plasmonic nanoantenna enables a thousand fold-enhanced fluorescence brightness allowing single-molecule analysis to be carried out in a zeptolitre volume at physiological concentrations.

Over the past few decades, two techniques in particular have opened up new avenues for probing molecular processes: ultrafast spectroscopy and single-molecule detection. The two approaches have now been combined, enabling not only the observation but also the manipulation of vibrational wave-packet interference at ambient conditions. The technique could help to unravel details of molecular function and dynamics in systems as diverse as light-harvesting complexes, photoactive proteins and conjugated polymers.

Nanoantennas provide improvements in detection and fluorescence of nanoscale objects, which are usually limited to electric dipole radiation. By exploiting coupling to nanowire antennas, Curto et al. show controlled multipolar emission of a quantum dot, offering a novel multipolar photon source.

Quantum processes may have an important role in photosynthetic light-harvesting complexes, but their low fluorescence efficiency impedes studies. By coupling them to gold nanoantennas, Wientjes et al.show over 500 times enhancement of fluorescence from single molecules of light-harvesting complex 2.

In single-molecule spectroscopy typically only emission spectra are recorded. Here, the authors develop a technique to record single-molecule excitation spectra under ambient conditions, which is robust against blinking and bleaching, and reveals a large distribution of spectra across the molecule ensemble.

Holography of incoherent emission from SERS probes allows multiplexed single-particle localization in three dimensions in one shot using a wide-field microscope.

Antennas are used to direct the propagation of radio waves. However, this directionality is not so easy to achieve at optical frequencies. Optical antennas that can direct the emission from single fluorescent molecules represent an intriguing route to single-photon sources.

Optical excitation of graphene can generate a photovoltage in less than 50 femtoseconds, and can result in efficient electron heating.

Spatiotemporal thermoelectric microscopy enables the observation of electronic heat flow in graphene in diffusive and hydrodynamic regimes at room temperature, as well as a controlled transition from a Fermi liquid to Dirac fluid.