Tripartitetobipartite Entanglement Transformation by Stochastic Local Operations and Classical Communication and the Structure of Matrix Spaces
Abstract
We study the problem of transforming a tripartite pure state to a bipartite one using stochastic local operations and classical communication (SLOCC). It is known that the tripartitetobipartite SLOCC convertibility is characterized by the maximal Schmidt rank of the given tripartite state, i.e. the largest Schmidt rank over those bipartite states lying in the support of the reduced density operator. In this paper, we further study this problem and exhibit novel results in both multicopy and asymptotic settings. In the multicopy regime, we observe that the maximal Schmidt rank is strictly supermultiplicative, i.e. the maximal Schmidt rank of the tensor product of two tripartite pure states can be strictly larger than the product of their maximal Schmidt ranks. We then provide a full characterization of those tripartite states whose maximal Schmidt rank is strictly supermultiplicative when taking tensor product with itself. In the asymptotic setting, we focus on determining the tripartitetobipartite SLOCC entanglement transformation rate, which turns out to be equivalent to computing the asymptotic maximal Schmidt rank of the tripartite state, defined as the regularization of its maximal Schmidt rank. Despite the difficulty caused by the supermultiplicative property, we provide explicit formulas for evaluating the asymptotic maximal Schmidt ranks of two important families of tripartite pure states, by resorting to certain results of the structure of matrix spaces, including the study of matrix semiinvariants. These formulas give a sufficient and necessary condition to determine whether a given tripartite pure state can be transformed to the bipartite maximally entangled state under SLOCC, in the asymptotic setting. Applying the recent progress on the noncommutative rank problem, we can verify this condition in deterministic polynomial time.
 Publication:

arXiv eprints
 Pub Date:
 December 2016
 arXiv:
 arXiv:1612.06491
 Bibcode:
 2016arXiv161206491L
 Keywords:

 Quantum Physics
 EPrint:
 23 pages, v2 has improved presentation, numerous typos and proof corrected, and many more references. Comments are welcome!