7 papers · 1 filter
Sharp Continuity of Petz and Sandwiched Rényi Conditional Entropies
Hao-Chung Cheng, Po-Chieh Liu
We determine the sharp modulus of continuity, in trace distance, of the optimized Petz and sandwiched Rényi conditional entropies for every order . If two bipartit…
Device-independent Quantum Key Distribution in the commuting operator framework
Gereon KoÃmann, René Schwonnek, Po-Chieh Liu +1
Device-independent quantum key distribution (DIQKD) is arguably the gold standard for secure quantum communication, as it aims to rely only on observed input-output statistics of a…
Multiple Quantum Hypothesis Testing: One-Shot Pairwise Bounds and Sharp Asymptotics
Hao-Chung Cheng, Po-Chieh Liu
We consider Bayesian discrimination among multiple quantum states and establish a dimension-free one-shot upper bound on the minimum probability of error in terms of the sum of pai…
Error Exponents for Quantum Packing Problems via An Operator Layer Cake Theorem
Hao-Chung Cheng, Po-Chieh Liu
In this work, we prove a one-shot random coding bound for classical-quantum channel coding, a problem conjectured by Burnashev and Holevo in 1998. By choosing the optimal input dis…
The operator layer cake theorem is equivalent to Frenkel's integral formula
Hao-Chung Cheng, Gilad Gour, Ludovico Lami +1
The operator layer cake theorem provides an integral representation for the directional derivative of the operator logarithm in terms of a family of projections [arXiv:2507.06232].…
Sharp estimates of quantum covering problems via a novel trace inequality
Hao-Chung Cheng, Li Gao, Christoph Hirche +2
In this paper, we prove a novel trace inequality involving two operators. As applications, we sharpen the one-shot achievability bound on the relative entropy error in a wealth of…