Bipartite separability of one parameter families of states using   conditional quantum relative Tsallis entropy
  In any bipartition of a quantum state, it is proved that the negative values of the conditional version of sandwiched Tsallis relative entropy necessarily implies quantum entanglement. For any N, the separability ranges in the $1:N-1$ partition of symmetric one parameter families of noisy $N$-qubit W, GHZ, states are determined using the conditional quantum relative Tsallis entropy approach. The 1:N-1 separability range matches exactly with the range obtained through positive partial transpose criterion, for all N. The advantages of using non-commuting version of $q$-conditional relative Tsallis entropy is brought out through this and other one-parameter families of states. 
Anantha S Nayak, Sudha, A. K. Rajagopal and A. R. Usha Devi
quant-ph