Quantum transport in $\nu=2/3$ spin-singlet quantum Hall edges

Tunneling conductance $G(T)$ through a constricted point contact is studied for the $\nu=2/3$ spin-singlet edges. Including spin-flip tunneling, Zeeman splitting and random magnetic impurities, we discuss the various crossovers of $G(T)$ as a function of the temperature $T$. The behavior of $G(T)$ is found to be quite different for spin-singlet and spin-polarized cases, and hence $G(T)$ is expected to serve as an experimental probe for the polarized-unpolarized transition at $\nu=2/3$.