{"title":"Effect of unital and non-unital channels on faithfulness of two-qubit entanglement","authors":"Longjiang Liu, Lingchao Li","doi":"10.1007/s11128-024-04619-z","DOIUrl":null,"url":null,"abstract":"<div><p>States whose entanglement can be detected by a fidelity-based entanglement witness are faithful. In this paper, we introduce a new necessary and sufficient condition for identifying faithful states. This condition is based on the trace norm. With the help of this condition, we investigate the effect of local channels on the faithfulness of two-qubit entangled states. The result shows that all the unital channels cannot enhance the faithfulness of entangled states. Some non-unital channels can improve the faithfulness of a restricted set of entangled states and even change an unfaithful entangled state to a faithful one. However, the faithfulness of all the states with maximally mixed marginals can only decrease when subjected to local channels.</p></div>","PeriodicalId":746,"journal":{"name":"Quantum Information Processing","volume":"24 1","pages":""},"PeriodicalIF":2.2000,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Quantum Information Processing","FirstCategoryId":"101","ListUrlMain":"https://link.springer.com/article/10.1007/s11128-024-04619-z","RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"PHYSICS, MATHEMATICAL","Score":null,"Total":0}
引用次数: 0
Abstract
States whose entanglement can be detected by a fidelity-based entanglement witness are faithful. In this paper, we introduce a new necessary and sufficient condition for identifying faithful states. This condition is based on the trace norm. With the help of this condition, we investigate the effect of local channels on the faithfulness of two-qubit entangled states. The result shows that all the unital channels cannot enhance the faithfulness of entangled states. Some non-unital channels can improve the faithfulness of a restricted set of entangled states and even change an unfaithful entangled state to a faithful one. However, the faithfulness of all the states with maximally mixed marginals can only decrease when subjected to local channels.
期刊介绍：
Quantum Information Processing is a high-impact, international journal publishing cutting-edge experimental and theoretical research in all areas of Quantum Information Science. Topics of interest include quantum cryptography and communications, entanglement and discord, quantum algorithms, quantum error correction and fault tolerance, quantum computer science, quantum imaging and sensing, and experimental platforms for quantum information. Quantum Information Processing supports and inspires research by providing a comprehensive peer review process, and broadcasting high quality results in a range of formats. These include original papers, letters, broadly focused perspectives, comprehensive review articles, book reviews, and special topical issues. The journal is particularly interested in papers detailing and demonstrating quantum information protocols for cryptography, communications, computation, and sensing.
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