Realization of symmetric sharing of entanglement in semiconductor   microcrystallites coupled by a cavity field
  The entanglement of excitonic states in a system of $N$ spatially separated semiconductor microcrystallites is investigated. The interaction among the different microcrystallites is mediated by a single-mode cavity field. It is found that the symmetric sharing of the entanglement (measured by the concurrence) between any pair of the excitonic state with $N$ qubits defined by the number states (vacuum and a single-exciton states) or the coherent states (odd and even coherent states) can be prepared by the cavity field for this system. 
Yu-xi Liu, Adam Miranowicz, Masato Koashi, and Nobuyuki Imoto