Tavis-Cummings model and collective multi-qubit entanglement in trapped   ions
  We present a method of generating collective multi-qubit entanglement via global addressing of an ion chain following the guidelines of the Tavis-Cummings model, where several qubits are coupled to a collective motional mode. We show that a wide family of Dicke states and irradiant states can be generated by single global laser pulses, unitarily or helped with suitable postselection techniques. 
A. Retzker, E. Solano, B. Reznik