  We investigate theoretically the electron states in HgTe quantum dots (QDs)
with inverted band structures. In sharp contrast to conventional semiconductor
quantum dots, the quantum states in the gap of HgTe quantum dot with an
inverted band structure are fully spin-polarized, and show ring-like density
distributions near the boundary of the QD and spin-angular momentum locking.
The persistent charge currents and magnetic moments, i.e., the Aharonov-Bohm
effect, can be observed in such QD structure and oscillate with increasing
magnetic fields. This feature offers us a practical way to detect these exotic
ring-like edge states using the SQUID technique.
