QUANTUM ENTANGLEMENT AND MULTIPARTITE SYMMETRIC STATES

Ved Prakash Gupta, Prabha Mandayam, Viakalathur Shankar Sunder

Mohammed Daoud A, El Bouâzzaoui Choubabi

We investigate the generation of multipartite entangled SU (k+1) coherent states using a quantum network involving a sequence of k beam splitters. We particularly investigate the entanglement in multipartite SU(2) coherent states (k = 1). We employ the concurrence as measure of the degree of bipartite entanglement.

Fabio Benatti

Andreas Osterloh, Jens Siewert

We present a method to construct entanglement measures for pure states of multipartite qubit systems. The key element of our approach is an antilinear operator that we call comb in reference to the hairy-ball theorem. For qubits (i.e. spin 1/2) the combs are automatically invariant under SL (2, ℂ). This implies that the filters obtained from the combs are entanglement monotones by construction. We give alternative formulae for the concurrence and the 3-tangle as expectation values of certain antilinear operators. As an application we discuss inequivalent types of genuine four-, five- and six-qubit entanglement.

Miłosz R. Michalski

Marek Kuś