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EnglishIt 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.
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.
| Titolo: | Toward computability of trace distance discord | |
| Autori: | ||
| Editore: | IOP Publishing and Deutsche Physikalische Gesellschaft | |
| Data di pubblicazione: | 2014 | |
| Rivista: | ||
| Digital Object Identifier (DOI): | http://dx.doi.org/10.1088/1367-2630/16/1/013038 | |
| Parole Chiave: | X-STATES; QUANTUM; ENTANGLEMENT; DYNAMICS | |
| Parole chiave (inglese): | Bell-diagonal states e trace distance discord Physics quantum states trace distance | |
| Handle: | http://hdl.handle.net/11384/38620 | |
| Appare nelle tipologie: | 1.1 Articolo in rivista |
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| File | Descrizione | Tipologia | Licenza | |
|---|---|---|---|---|
| Toward-computability.pdf | full text | Altro materiale allegato |  | Open Access Visualizza/Apri |
http://hdl.handle.net/11384/38620
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