Quantum Gambling Using Three Nonorthogonal States
  We provide a quantum gambling protocol using three (symmetric) nonorthogonal states. The bias of the proposed protocol is less than that of previous ones, making it more practical. We show that the proposed scheme is secure against non-entanglement attacks. The security of the proposed scheme against entanglement attacks is shown heuristically. 
W.-Y. Hwang, K. Matsumoto