7 papers
Quantum estimation, channel orders, and private capacity
Christoph Hirche
Recent examples have shown that zero private capacity need not imply antidegradability and that two channels with zero private capacity can nevertheless transmit private informatio…
The exact strong converse exponent for private communication over quantum channels
Hao-Chung Cheng, Christoph Hirche, Marco Tomamichel
We determine the exact strong converse exponent for secret-key transmission and generation over general finite-dimensional quantum wiretap channels, measuring reliability and secre…
Conditional contraction coefficients and their applications to quantum networks
Christoph Hirche, Ian George, Theshani Nuradha +1
Contraction coefficients quantify the loss of distinguishability induced by a channel and provide a strong form of the data-processing inequality. While standard contraction coeffi…
Information Contraction under -Differentially Private Mechanisms
Theshani Nuradha, Ian George, Christoph Hirche
The distinguishability quantified by information measures after being processed by a private mechanism has been a useful tool in studying various statistical and operational tasks…
Non-Linear Strong Data-Processing for Quantum Hockey-Stick Divergences
Theshani Nuradha, Ian George, Christoph Hirche
Data-processing is a desired property of classical and quantum divergences and information measures. In information theory, the contraction coefficient measures how much the distin…
Quantum Doeblin Coefficients: Interpretations and Applications
Ian George, Christoph Hirche, Theshani Nuradha +1
In classical information theory, the Doeblin coefficient of a classical channel provides an efficiently computable upper bound on the total-variation contraction coefficient of the…
Quantum Doeblin coefficients: A simple upper bound on contraction coefficients
Christoph Hirche
Contraction coefficients give a quantitative strengthening of the data processing inequality. As such, they have many natural applications whenever closer analysis of information p…