Quantum rectifiers from harmonic mixing

We investigate dissipative quantum transport in extended periodic systems that are subjected to electric harmonic mixing fields E-hm(t) = E-1 cos(Omega t) + E-2 cos(2 Omega t+phi) Although such a drive possesses no net bias on average, the interplay of quantum dissipation and nonlinear response causes a finite directed current. We thus discover the paradigm of a dissipative quantum rectifier. The quantum current exhibits multiple reversals when driven in the nonadiabatic regime. As a function of temperature the quantum current displays a bell-shaped characteristic -constituting the benchmark for quantum stochastic resonance. Moreover, harmonic mixing also serves as a novel tool to selectively control quantum diffusion.