Engineering valley quantum interference in anisotropic van der Waals heterostructures
In this paper, we present a novel route to manipulate the spontaneous valley coherence in two-dimensional valleytronic materials interfaced with other layered materials hosting anisotropic polaritonic modes. We propose two implementations---one, using anisotropic plasmons in phosphorene and another with hyperbolic phonon polaritons in $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{MoO}}_{3}$. In particular, we show the electrostatic tunability of the spontaneous valley coherence achieving robust valley coherence values in the near-infrared wavelengths at room temperature. The tunability of this valley coherence shown in these heterostructures would enable the realization of active valleytronic quantum circuitry.