dorsal/arxiv
View SchemaQuantum entanglement without eigenvalue spectra:multipartite case
| Authors | Hao Chen |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/0109056 |
| URL | https://arxiv.org/abs/quant-ph/0109056 |
Abstract
We introduce algebriac sets in the products of complex projective spaces for multipartite mixed states, which are independent of their eigenvalues and only measure the "position" of their eigenvectors, as their non-local invariants (ie. remaining invariant after local untary transformations). These invariants are naturally arised from the physical consideration of checking multipartite mixed states by measuring them with multipartite separable pure states. The algebraic sets have to be the sum of linear subspaces if the multipartite mixed state is separable, and thus we give a new separability criterion of multipartite mixed states. A continuous family of 4-party mixed states, whose members are separable for any 2:2 cut and entangled for any 1:3 cut (thus bound entanglement if 4 parties are isolated), is constructed and studied from our invariants and separability criterion. Examples of LOCC-incomparable entangled tripartite pure states are given to show it is hopeless to characterize the entanglement properties of tripartite pure states by only using the eigenvalue speactra of their partial traces. We also prove that at least $n^2+n-1$ terms of separable pure states, which are "orthogonal" in some sence, are needed to write a generic pure state in $H_A^{n^2} \otimes H_B^{n^2} \otimes H_C^{n^2}$ as a linear combination of them.
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"abstract": "We introduce algebriac sets in the products of complex projective spaces for\nmultipartite mixed states, which are independent of their eigenvalues and only\nmeasure the \"position\" of their eigenvectors, as their non-local invariants\n(ie. remaining invariant after local untary transformations). These invariants\nare naturally arised from the physical consideration of checking multipartite\nmixed states by measuring them with multipartite separable pure states. The\nalgebraic sets have to be the sum of linear subspaces if the multipartite mixed\nstate is separable, and thus we give a new separability criterion of\nmultipartite mixed states. A continuous family of 4-party mixed states, whose\nmembers are separable for any 2:2 cut and entangled for any 1:3 cut (thus bound\nentanglement if 4 parties are isolated), is constructed and studied from our\ninvariants and separability criterion. Examples of LOCC-incomparable entangled\ntripartite pure states are given to show it is hopeless to characterize the\nentanglement properties of tripartite pure states by only using the eigenvalue\nspeactra of their partial traces. We also prove that at least $n^2+n-1$ terms\nof separable pure states, which are \"orthogonal\" in some sence, are needed to\nwrite a generic pure state in $H_A^{n^2} \\otimes H_B^{n^2} \\otimes H_C^{n^2}$\nas a linear combination of them.",
"arxiv_id": "quant-ph/0109056",
"authors": [
"Hao Chen"
],
"categories": [
"quant-ph"
],
"title": "Quantum entanglement without eigenvalue spectra:multipartite case",
"url": "https://arxiv.org/abs/quant-ph/0109056"
},
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