Coulomb drag between ballistic one-dimensional electron systems

Abstract

The presence of pronounced electronic correlations in one-dimensional systems\nstrongly enhances Coulomb coupling and is expected to result in distinctive\nfeatures in the Coulomb drag between them that are absent in the drag between\ntwo-dimensional systems. We review recent Fermi and Luttinger liquid theories\nof Coulomb drag between ballistic one-dimensional electron systems, and give a\nbrief summary of the experimental work reported so far on one-dimensional drag.\nBoth the Fermi liquid (FL) and the Luttinger liquid (LL) theory predict a\nmaximum of the drag resistance R_D when the one-dimensional subbands of the two\nquantum wires are aligned and the Fermi wave vector k_F is small, and also an\nexponential decay of R_D with increasing inter-wire separation, both features\nconfirmed by experimental observations. A crucial difference between the two\ntheoretical models emerges in the temperature dependence of the drag effect.\nWhereas the FL theory predicts a linear temperature dependence, the LL theory\npromises a rich and varied dependence on temperature depending on the relative\nmagnitudes of the energy and length scales of the systems. At higher\ntemperatures, the drag should show a power-law dependence on temperature, $R_D\n\\~ T^x$, experimentally confirmed in a narrow temperature range, where x is\ndetermined by the Luttinger liquid parameters. The spin degree of freedom plays\nan important role in the LL theory in predicting the features of the drag\neffect and is crucial for the interpretation of experimental results.\n