Entanglement in Algebraic Quantum Mechanics: Majorana fermion systems
  Many-body entanglement is studied within the algebraic approach to quantum physics in systems made of Majorana fermions. In this framework, the notion of separability stems from partitions of the algebra of observables and properties of the associated correlation functions, rather than on particle tensor products. This allows obtaining a complete characterization of non-separable Majorana fermion states. These results may find direct applications in quantum metrology: using Majorana systems, sub-shot noise accuracy in parameter estimations can be achieved without preliminary, resource consuming, state entanglement operations. 
F. Benatti and R. Floreanini
quant-ph cond-mat.other hep-th math-ph math.MP