We derive Margolus-Levitin and Mandelstamm-Tamm type bound on the quantum speed limit time for the creation and decay of quantum correlations by an amount in a quantum system evolving under the influence of its ambient environment. The minimum distance of a non-classical state from an appropriate set of classical states is a legitimate measure of the quantumness of the state. We consider entanglement and quantum discord measures of quantum correlations, quantified using the Bures distance-based measure. To demonstrate the impact of quantum noise on this speed limit time for quantum correlations, we estimate the quantum speed limit time for the creation and decay of quantum correlations for a two-qubit system under modified OUN dephasing and collective two-qubit decoherence channels.
Quantum-classical transitions have long attracted much attention. We study such transitions in quantum spin-(
j,1/2) systems at thermal equilibrium. Unlike previous work [Phys. Rev. A 73, 064302 (2006)], we find that the threshold temperature of quantum entanglement decreases with increasing spin
j and completely disappears in the limit $j\ensuremath{\rightarrow}\ensuremath{\infty}$. In the ground state of systems with highly symmetric interactions, the discord-type quantum correlations can exist even for arbitrarily large spin. Such correlations turn out to be unstable and are destroyed by small perturbations that violate the symmetry of the Hamiltonian. The stable quantum correlations gradually degrade as the spin
j grows and eventually vanish when the classical limit is reached.
We begin with the basic notions of limited shareability of quantum correlations, the so-called monogamous nature of quantum states and outline how this feature is manifested through a monogamy inequality. Not all measures of quantum correlations are suitable for bringing out the restricted shareability of correlations in a quantum state. While measures of bipartite correlations such as concurrence, quantum discord do not satisfy monogamy inequality for all categories of correlated quantum states, their second powers are found to do. There has also been a proposition that all multiparty quantum states can be made monogamous by considering positive integral powers of any quantum correlation measure (Ann. Phys. 348, 297 (2014)). We focus on this proposition and analyze whether satisfying monogamy inequality in terms of higher powers of a correlation measure implies limited shareability of correlations.