6533b86dfe1ef96bd12caa7d
RESEARCH PRODUCT
Toward computability of trace distance discord
Francesco CiccarelloTommaso TufarelliVittorio Giovannettisubject
Discrete mathematicsDYNAMICSBell-diagonal statesquantum statesQuantum Physicse trace distance discordComputabilityPhysicsGeneral Physics and AstronomyFOS: Physical sciencesClass (philosophy)Function (mathematics)State (functional analysis)Expression (computer science)Measure (mathematics)X-STATESX-STATES; QUANTUM; ENTANGLEMENT; DYNAMICSQubitquantum information quantum correlationsTrace distanceQuantum Physics (quant-ph)QUANTUMENTANGLEMENTtrace distanceMathematicsdescription
It is known that a reliable geometric quantifier of discord-like correlations can be built by employing the so-called trace distance. This is used to measure how far the state under investigation is from the closest "classical-quantum" one. To date, the explicit calculation of this indicator for two qubits was accomplished only for states such that 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 next 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.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2014-01-21 |