Coupled electron and hole quantum wires

We have investigated the effect of many-body correlations on properties of coupled electron-hole quantum wires using a Singwi-Tosi-Land-Sjölander approach. At $r_s=4\mathrm{}$ the acoustic collective mode traverses the single-electron excitation region as a narrow resonance peak and reemerges in the undamped region on the high-$q$ side of the excitation region. The acoustic collective mode, but not the optic mode, is sensitive to the separation between the wires. For $r_s>2.5\mathrm{}$ the effective interaction acting between the electrons which is mediated by the heavier holes becomes attractive when the separation between the wires drops to a critical value. For $0.8<~r_s<~2.5$ we detect a charge-density-wave ground state for small wire separations.