Summary
We study ground states of two-dimensional Bose-Einstein condensates with attractive interactions in a trap V(x) rotating at the velocity Omega. It is known that there exists a critical rotational velocity 0 < Omega* := Omega* (V)<=infinity and a critical number 0 < a* < infinity such that for any rotational velocity 0 <= Omega < Omega*, ground states exist if and only if the coupling constant a satisfies a < a *. For a general class of traps V(x), which may not be symmetric, we prove in this paper that up to a constant phase, there exists a unique ground state as a NE arrow a*, where Omega is an element of (0, Omega*) is fixed.