Coulomb drag between parallel ballistic quantum wires

The Coulomb drag between parallel, ballistic quantum wires is studied theoretically in the presence of a perpendicular magnetic field B. The transresistance $R_D$ shows peaks as a function of the Fermi level and splitting energy between the one-dimensional subbands of the wires. The sharpest peaks appear when the Fermi level crosses the subband extrema so that the Fermi momenta are small. Two other kinds of peaks appear when either intra- or inter-subband transitions of electrons have maximum probability; the intra-subband transitions correspond to a small splitting energy. $R_D$ depends on the field B in a nonmonotonic fashion: it decreases with B, as a result of the suppression of backscattering, and increases sharply when the Fermi level approaches the subband bottoms and the suppression is outbalanced by the increase of the Coulomb matrix elements and of the density of states.