Quantum and classical correlations in Bell three and four qubits,   related to Hilbert-Schmidt decomposition
  The present work studies quantum and classical correlations in three qubits and four qubits general Bell states, produced by operating with braid operators on the computational basis of states. The analogies between the general three qubits and four qubits Bell states and that of two qubits Bell states are discussed. The general Bell states are shown to be maximal entangled, i.e., with quantum correlations which are lost by tracing these states over one qubit, remaining only with classical correlations, as shown by HS decomposition. 
Yacob Ben-Aryeh
quant-ph cs.IT math.IT