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Toward computability of trace distance discord

Ciccarello, F.; Tufarelli, T.; Giovannetti, V.

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Authors

F. Ciccarello

V. Giovannetti



Abstract

It is known that a reliable geometric quantifier of discord-like correlations can be built by employing the so-called trace distance, which is used to measure how far the state under investigation is from the closest 'classical-quantum' state. To date, the explicit calculation of this indicator for two qubits has only been accomplished for states where the reduced density matrix of the measured party is maximally mixed, a class that includes Bell-diagonal states. Here, we first reduce the required optimization for a general two-qubit state to the minimization of an explicit two-variable function. Using this framework, we show that the minimum can be analytically worked out in a number of relevant cases, including quantum-classical and X states. This provides an explicit and compact expression for the trace distance discord of an arbitrary state belonging to either of these important classes of density matrices.

Journal Article Type Article
Acceptance Date Dec 9, 2013
Online Publication Date Jan 21, 2014
Publication Date Jan 21, 2014
Deposit Date Mar 13, 2018
Publicly Available Date Dec 3, 2018
Journal New Journal of Physics
Electronic ISSN 1367-2630
Publisher IOP Publishing
Peer Reviewed Peer Reviewed
Volume 16
Article Number 013038
DOI https://doi.org/10.1088/1367-2630/16/1/013038
Public URL https://nottingham-repository.worktribe.com/output/1113857
Publisher URL http://iopscience.iop.org/article/10.1088/1367-2630/16/1/013038/meta

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