Total, classical and quantum uncertainties generated by channels

Yizhou Liu ; Shunlong Luo ; Yuan Sun

Teoretičeskaâ i matematičeskaâ fizika, Tome 213 (2022) no. 2, pp. 347-369

Résumé

States and channels are fundamental and instrumental ingredients of quantum mechanics. Their interplay not only encodes information about states but also reflects uncertainties of channels. In order to quantify intrinsic uncertainties generated by channels, we exploit the action of a channel on an orthonormal basis in the space of observables from three different perspectives. The first concerns the uncertainty generated by a channel via noncommutativity between the Kraus operators of the channel and an orthonormal basis of observables, which can be interpreted as a kind of quantifier of the total uncertainty generated by a channel. The second concerns the uncertainty in terms of the Tsallis-$2$ entropy of the Jamiołkowski–Choi state associated with the channel via the channel–state duality, which can be interpreted as a quantifier of the classical uncertainty generated by a channel. The third concerns the uncertainty of a channel as the deviation from the identity channel in terms of the Hilbert–Schmidt distance, which can be interpreted as a kind of quantifier of the quantum uncertainty generated by a channel. We reveal basic properties of these quantifiers of uncertainties and establish a relation between them. We identify channels producing the minimal/maximal uncertainties for these three quantifiers. Finally, we explicitly evaluate these uncertainty quantifiers for various important channels, use them to gain insights into the channels from an information-theoretic perspective, and comparatively study the quantifiers.

Détail

Keywords: channel, total uncertainty, classical uncertainty, quantum uncertainty, Wigner–Yanase skew information, disturbance.