{"paper":{"title":"Fidelity spectrum and phase transitions of quantum systems","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["cond-mat.supr-con"],"primary_cat":"quant-ph","authors_text":"N. Paunkovic, P. D. Sacramento, V. R. Vieira","submitted_at":"2011-07-29T11:09:27Z","abstract_excerpt":"Quantum fidelity between two density matrices, $F(\\rho_1,\\rho_2)$ is usually defined as the trace of the operator ${\\cal F}=\\sqrt{\\sqrt{\\rho_1} \\rho_2 \\sqrt{\\rho_1}}$. We study the logarithmic spectrum of this operator, which we denote by {\\it fidelity spectrum}, in the cases of the $XX$ spin chain in a magnetic field, a magnetic impurity inserted in a conventional superconductor and a bulk superconductor at finite temperature. When the density matrices are equal, $\\rho_1=\\rho_2$, the fidelity spectrum reduces to the entanglement spectrum. We find that the fidelity spectrum can be a useful too"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1107.5931","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}