“…The multi‐dimensional equation often appears in the context of semi‐conductor modeling, and can be viewed as the evolution of the density of electrons with vanishing temperature of the simplified quantum drift‐diffusion model [1, 12]: Here is the temperature, the Planck constant, and the potential felt by the electrons, which splits into the classical electric potential and the Bohm potential, describing quantum effects. The equation can also be found in quantum hydrodynamics as the high friction limit of some quantum hydrodynamic equations, see References [14, 15, 21].…”