Nonreciprocal Coulomb drag in electron bilayers

We propose a mechanism and develop a theory for nonreciprocal Coulomb drag resistance. This effect arises in electron double-layer systems in the presence of an in-plane magnetic field in noncentrosymmetric conductors or in bilayers with spontaneously broken time-reversal symmetry and without Galilean invariance. We demonstrate the significance of this effect by examining the hydrodynamic regime of the electron liquid. The nonreciprocal component of the transresistance is shown to sensitively depend on the intrinsic conductivity, viscosity of the fluid, and the emergent nonreciprocity parameter.