Electrons, as quantum particles, display wave-like behavior. Forming a crystalline phase of electrons requires not only cooling but also strong Coulomb (repulsive) forces to counteract their wave-like nature. When this balance is achieved, electrons can arrange into a Wigner crystal. By adjusting electron density, a phase transition between a crystalline and liquid state can occur....

The structural engineering of van der Waals (vdW) heterostructures via stacking and twisting has been recently used to create moiré superlattices, enabling engineering of the optical and electronic properties of solid-state systems reminiscent to ultracold atomic gases. Indeed, recent experiments on transition metal dichalcogenides (TMDs), a class of layered vdW semiconductors, have shown that moiré...

Conventional mirrors have fundamental thickness limitations: the skin depth for metallic mirrors, and the wavelength of light for dielectric mirrors. Recently, the Park Group has demonstrated that these limitations can be overcome with the atomically thin semiconductor molybdenum diselenide [1]. To understand how this can be achieved, one has to consider how light is reflected...