2000/01/31 by Anthony Sudbery
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.1088/0305-4470/34/3/323
published as J.Phys.A 34 (2001), 643-652 · LateX, 13 pages. Minor typoes corrected. Published version
arxiv created 2001/01/20 · arxiv updated 2009/12/01
We study invariants of three-qubit states under local unitary transformations, i.e. functions on the space of entanglement types, which is known to have dimension 6. We show that there is no set of six independent polynomial invariants of degree less than or equal to 6, and find such a set with maximum degree 8. We describe an intrinsic definition of a canonical state on each orbit, and discuss the (non-polynomial) invariants associated with it.