Multidimensional nanoscopic chiroptics

Nanoscopic chiroptics studies the spin-dependent asymmetric light-matter interactions at the nanoscale, where the asymmetry can stem from the intrinsic properties of materials, structures or light. This Perspective establishes an overarching framework for nanoscopic chiroptics across the spatial, moment and integrated spatial-momentum dimensions, and discusses applications enabled by this approach. Nanoscopic chiroptics studies the spin-dependent asymmetric light-matter interactions at the nanoscale, where the asymmetry can stem from the intrinsic properties of materials, structures, light or combinations thereof. With the emergence of low-dimensional materials platforms, such as metasurfaces, transition metal dichalcogenides and perovskites, nanoscopic chiroptics has been extended from the far field to the near field, and further developed from the spatial dimension, to the momentum dimension and the integrated spatial-momentum dimension. This expansion of nanoscopic chiroptics across dimensions has uncovered new physical mechanisms and manifestations of chiral effects. It also led to applications such as valleytronics, chiral sensing and chiral photochemistry. This Perspective focuses on the progress in nanoscopic chiroptics through the lens of the associated dimensionalities, discussing the opportunities in integrated optics, photochemistry, quantum optics and biochemical synthesis and analysis.