{"work":{"id":"5c222685-2fde-4c0f-9c3b-30fb4d0cb721","openalex_id":null,"doi":null,"arxiv_id":"quant-ph/9604005","raw_key":null,"title":"Separability Criterion for Density Matrices","authors":null,"authors_text":"A","year":1996,"venue":"quant-ph","abstract":"A quantum system consisting of two subsystems is separable if its density matrix can be written as $\\rho=\\sum_A w_A\\,\\rho_A'\\otimes\\rho_A''$, where $\\rho_A'$ and $\\rho_A''$ are density matrices for the two subsytems. In this Letter, it is shown that a necessary condition for separability is that a matrix, obtained by partial transposition of $\\rho$, has only non-negative eigenvalues. This criterion is stronger than Bell's inequality.","external_url":"https://arxiv.org/abs/quant-ph/9604005","cited_by_count":null,"metadata_source":"pith","metadata_fetched_at":"2026-07-03T06:47:43.184867+00:00","pith_arxiv_id":"quant-ph/9604005","created_at":"2026-05-09T06:00:36.484779+00:00","updated_at":"2026-07-03T06:47:43.184867+00:00","title_quality_ok":true,"display_title":"Separability Criterion for Density Matrices","render_title":"Separability Criterion for Density Matrices"},"hub":{"state":{"work_id":"5c222685-2fde-4c0f-9c3b-30fb4d0cb721","tier":"hub","tier_reason":"10+ Pith inbound or 1,000+ external citations","pith_inbound_count":11,"external_cited_by_count":null,"distinct_field_count":4,"first_pith_cited_at":"2022-12-22T14:32:49+00:00","last_pith_cited_at":"2026-05-28T18:00:02+00:00","author_build_status":"not_needed","summary_status":"needed","contexts_status":"needed","graph_status":"needed","ask_index_status":"not_needed","reader_status":"not_needed","recognition_status":"not_needed","updated_at":"2026-06-29T09:48:39.692565+00:00","tier_text":"hub"},"tier":"hub","role_counts":[{"context_role":"background","n":4},{"context_role":"method","n":2}],"polarity_counts":[{"context_polarity":"background","n":4},{"context_polarity":"use_method","n":2}],"runs":{},"summary":{},"graph":{},"authors":[]}}