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Unitary braid matrices: bridge between topological and quantum entanglements. (English) Zbl 1264.81238

Summary: Braiding operators corresponding to the third Reidemeister move in the theory of knots and links are realized in terms of parametrized unitary matrices for all dimensions. Two distinct classes are considered. Their (nonlocal) unitary actions on separable pure product states of three identical subsystems (i.e., the spin projections of three particles) are explicitly evaluated for all dimensions. This, for our classes, is shown to generate entangled superposition of four terms in the base space. The 3-body and 2-body entanglements (in three 2-body subsystems), the 3 tangles, and 2 tangles are explicitly evaluated for each class. For our matrices, these are parametrized. Varying parameters they can be made to sweep over the domain (0, 1). Thus, braiding operators corresponding to over- and undercrossings of three braids and, on closing ends, to topologically entangled Borromean rings are shown, in another context, to generate quantum entanglements. For higher dimensions, starting with different initial triplets one can entangle by turns, each state with all the rest. A specific coupling of three angular momenta is briefly discussed to throw more light on three body entanglements.

MSC:

81R05 Finite-dimensional groups and algebras motivated by physics and their representations
81P40 Quantum coherence, entanglement, quantum correlations
57M27 Invariants of knots and \(3\)-manifolds (MSC2010)
20F36 Braid groups; Artin groups