Year: 2025
Type: article
Abstract: We introduce a new framework for quantum channel discrimination in an adversarial setting, where the tester plays against an adversary. We show that in asymmetric hypothesis testing, the optimal type-II error exponent is precisely characterized by a new notion of quantum channel divergence (termed the minimum output channel divergence). This serves as a direct analog of the quantum Stein's lemma in this new framework, and complements previous studies on "best-case" channel discrimination, thereby providing a complete understanding of the ultimate limits of quantum channel discrimination. Notably, the optimal error exponent can be achieved by simple nonadaptive adversarial strategies, and despite the need for regularization it remains efficiently computable and satisfies the strong converse property in general. Furthermore, we show that entropy accumulation, a powerful tool in quantum cryptography, can be reframed as an adversarial channel discrimination problem, establishing a new connection between quantum information theory and quantum cryptography.
Source: Physical Review Letters
DOI: 10.1103/mtbj-grbk
Authors: Kun Fang, Hamza Fawzi, Omar Fawzi
Language: English
Subfield: Artificial Intelligence
Field: Computer Science
Domain: Physical Sciences
Open Access status: green
Funders: Chinese University of Hong Kong, Shenzhen, European Commission, Agence Nationale de la Recherche, National Natural Science Foundation of China, Guangdong Science and Technology Department, Shenzhen Fundamental Research Program, Horizon 2020 Framework Programme, European Research Council, Shenzhen Science and Technology Innovation Program
Awards: G1190173965, G1272605949, G1583853050, G1940717241, G2330084786, G5271502856, Verification of quantum technologies, systems and applications, G5388051471, G5508686167, QuantERA II ERA-NET Cofund in Quantum Technologies, Distribution Quantique de clés avec des boites noires, G7362582964, G7461596751, Quantum Secure Networks Partnership
OpenAlex ID: W4417223359