Phys. Rev. Lett. 121, 123606 (2018)

Placing a 2D material in front of a partially reflecting broadband mirror can dramatically enhance the nonlinear interaction between individual photons, according to a US team of researchers. In a theoretical study, Dominik Wild and co-workers, from Harvard University and the University of Connecticut, discovered that a transition metal dichalcogenide (TMD) monolayer acts as a perfect reflector even though it is thinner than a wavelength. However, when the distance between the TMD monolayer and the mirror is close to half-integer multiples of the exciton resonance wavelength, perfect transmission is achieved. The phenomenon is similar to blockade-type effects that occur in quantum-well cavities, where the presence of a single polariton blocks subsequent photons from entering the cavity.