dorsal/arxiv
View SchemaCones of ball-ball separable elements
| Authors | Roland Hildebrand |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/0503194 |
| URL | https://arxiv.org/abs/quant-ph/0503194 |
| DOI | 10.1103/PhysRevA.75.062330 |
Abstract
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_1 \otimes E_2 is called B_1 \otimes B_2-separable if it is contained in the convex conic hull of elements of the form w_1 \otimes w_2, where w_1 \in B_1, w_2 \in B_2. We study the cone formed by the separable elements in E_1 \otimes E_2. We determine the largest faces of this cone via a description of the extreme rays of the dual cone, i.e. the cone of the corresponding positive linear maps. We compute the radius of the largest ball centered around v_1 \otimes v_2 that consists of separable elements. As an application we obtain lower bounds on the radius of the largest ball of separable unnormalized states around the identity matrix for a multi-qubit system. These bounds are approximately 12% better than the best previously known. Our results are extendible to the case where B_1,B_2 are solid ellipsoids.
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"abstract": "Let B_1,B_2 be balls in finite-dimensional real vector spaces E_1,E_2,\ncentered around unit length vectors v_1,v_2 and not containing zero. An element\nin the tensor product space E_1 \\otimes E_2 is called B_1 \\otimes B_2-separable\nif it is contained in the convex conic hull of elements of the form w_1 \\otimes\nw_2, where w_1 \\in B_1, w_2 \\in B_2. We study the cone formed by the separable\nelements in E_1 \\otimes E_2. We determine the largest faces of this cone via a\ndescription of the extreme rays of the dual cone, i.e. the cone of the\ncorresponding positive linear maps. We compute the radius of the largest ball\ncentered around v_1 \\otimes v_2 that consists of separable elements. As an\napplication we obtain lower bounds on the radius of the largest ball of\nseparable unnormalized states around the identity matrix for a multi-qubit\nsystem. These bounds are approximately 12% better than the best previously\nknown. Our results are extendible to the case where B_1,B_2 are solid\nellipsoids.",
"arxiv_id": "quant-ph/0503194",
"authors": [
"Roland Hildebrand"
],
"categories": [
"quant-ph"
],
"doi": "10.1103/PhysRevA.75.062330",
"title": "Cones of ball-ball separable elements",
"url": "https://arxiv.org/abs/quant-ph/0503194"
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