  We calculate potentials between a proton and a $\Xi^0$ (hyperon with
strangeness -2) through the equal-time Bethe-Salpeter wave function, employing
quenched lattice QCD simulations with the plaquette gauge action and the Wilson
quark action on (4.5 fm)^4 lattice at the lattice spacing $a \simeq 0.14$ fm.
The ud quark mass in our study corresponds to $m_{\pi}\simeq 0.37$ and 0.51
GeV, while the s quark mass corresponds to the physical value of $m_K$. The
central $p \Xi^0$ potential has a strong (weak) repulsive core in the $^1S_0$
($^3S_1$) channel for $r \lsim 0.6$ fm, while the potential has attractive well
at the medium and long distances (0.6 fm $\lsim r \lsim 1.2$ fm) in both
channels. The sign of the $p \Xi^0$ scattering length and its quark mass
dependence indicate a net attraction in both channels at low energies.
