Researchers have outlined current developments in developing moiré photonics and optoelectronics. Moiré superlattices are artificial quantum materials created by vertically stacking two or more two-dimensional (2D) layered materials with a little lattice mismatch and/or a slight rotational twist. They present a potential landscape with a length scale much wider than the crystal periodicity of the individual 2D layers. They offer a fresh approach to designing band structures and, in turn, a wide range of unusual quantum phenomena.
For instance, the formation of flat bands and a rich phase diagram of strongly correlated and topological states, such as superconductivity, orbital magnetism, Wigner crystal states, Chern insulator states, and quantum simulators, are possible when the moiré potential landscape folds the electronic band structure into a mini-Brillouin zone.
Light couples with moiré superlattices create previously unimaginable opportunities for observing numerous emerging photonic and optoelectronic phenomena for the first time. As an illustration, moiré superlattices provide a powerful method for creating excitonic quasiparticles in both real and momentum spaces, giving rise to moiré excitons that resemble quantum dots and those that are Bragg-umklapp moiré excitons, respectively.
A wide range of fascinating photonic and optoelectronic properties, including but not limited to moiré excitons/polaritons, resonantly hybridized excitons, reconstructed collective excitations, strong mid-/far-infrared photoresponses, terahertz single-photon detection, and symmetry-breaking optoelectronics, have been observed in moiré superlattices over the past few years with unprecedented speed.
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