# Non-Positive Partial Transpose Subspaces Can be as Large as Any Entangled Subspace

Authors
Type
Published Article
Publication Date
Jun 19, 2013
Submission Date
May 01, 2013
Identifiers
DOI: 10.1103/PhysRevA.87.064302
Source
arXiv
It is known that, in an $(m \otimes n)$-dimensional quantum system, the maximum dimension of a subspace that contains only entangled states is (m-1)(n-1). We show that the exact same bound is tight if we require the stronger condition that every state with range in the subspace has non-positive partial transpose. As an immediate corollary of our result, we solve an open question that asks for the maximum number of negative eigenvalues of the partial transpose of a quantum state. In particular, we give an explicit method of construction of a bipartite state whose partial transpose has (m-1)(n-1) negative eigenvalues, which is necessarily maximal, despite recent numerical evidence that suggested such states may not exist for large m and n.