Ground state structure and conductivity of quantum wires of infinite length and finite width

We have studied the ground state structure of quantum strips within the local spin-density approximation, for a range of electronic densities between $\sim$ 5$\times {10}^4$ and 2$\times {10}^6$ cm${}^{-1}$ and several strengths of the lateral confining potential. The results have been used to address the conductance $G$ of quantum strips. At low density, when only one subband is occupied, the system is fully polarized and $G$ takes a value which is close to 0.7(2e${}^2\mathrm{/}h$), decreasing with increasing electron density in agreement with experiments. At higher densities the system becomes paramagnetic and $G$ takes a value near (2e${}^2\mathrm{/}h$), showing a similar decreasing behaviour with increasing electron density. In both cases, the physical parameter that determines the value of the conductance is the ratio $K\mathrm{/}{K}_0$ of the compressibility of the system over the free one.