  Analyzing carefully an experimentally feasible non-entangled single qubit
quantum secret sharing protocol and its modified version [Phys. Rev. Lett. 95,
230505 (2005); ibid. 98, 028902 (2007)], it is found that both versions are
insecure against coherent attacks though the original idea is so remarkable. To
overcome this fatal flaw, here we propose a protocol with a distinct security
checking strategy, which still involves single qubit operations only, making it
possible to achieve better security of quantum secret sharing with current
technology.
