60 citations · 138 across the 20 of their papers we have counts for
5 papers · 1 filter
Entangled states close to the maximally mixed state
Roland Hildebrand
We give improved upper bounds on the radius of the largest ball of separable states of an m-qubit system around the maximally mixed state. The ratio between the upper bound and the…
Concurrence of Lorentz-positive maps
Roland Hildebrand
Let L_n be the n-dimensional Lorentz cone. A linear map M from R^m to R^n is called Lorentz-positive if M[L_m] is contained in L_n. We extend the notion of concurrence, which was i…
Separable balls around the maximally mixed state for a 3-qubit system
Roland Hildebrand
We obtain a new lower bound on the radius of the largest ball of separable unnormalized states around the identity matrix for a 3-qubit system. This also enables us to improve the…
Cones of ball-ball separable elements
Roland Hildebrand
Let B_1,B_2 be balls in finite-dimensional real vector spaces E_1,E_2, centered around unit length vectors v_1,v_2 and not containing zero. An element in the tensor product space E…
PPT from spectra
Roland Hildebrand
In this contribution we solve the following problem. Let H_{nm} be a Hilbert space of dimension nm, and let A be a positive semidefinite self-adjoint linear operator on H_{nm}. Und…