Quantum discord of SU(2) invariant states

TL;DR

This paper analytically computes the quantum discord for SU(2) invariant states involving spin-$j$ and spin-1/2 subsystems, revealing high discord levels even in separable states, with potential implications for quantum computation.

Contribution

It provides the first analytical calculation of quantum discord for SU(2) invariant states and compares it with entanglement, highlighting the persistence of discord in separable states.

Findings

Quantum discord is significantly higher than in similar symmetric states.

Quantum discord remains large even when states are nearly separable.

Results suggest potential applications in quantum computation using discord.

Abstract

We have analytically calculated the quantum discord for a system composed of spin-$j$ and spin-1/2 subsystems possessing SU(2) symmetry. We have compared our results with the quantum discord of states having similar symmetries and seen that in our case amount of quantum discord is much higher. Moreover, using the well known entanglement properties of these states, we have also compared their quantum discord with entanglement. Although the system under consideration is separable nearly all throughout of its parameter space as $j$ increases, we have seen that discord content remains significantly large. Investigation of quantum discord in SU(2) invariant states may find application in quantum computation protocols that utilize quantum discord as a resource since they arise in many real physical systems.