The decay of quantum correlations between quantum dot spin qubits and the characteristics of its magnetic field dependence

Abstract

We address the question of the role of quantum correlations beyond entanglement in context of quantum magnetometry. To this end, we study the evolution of the quantum discord, measured by the rescaled discord, of two electron-spin qubits interacting with an environment of nuclear spins via the hyperfine interaction. We have found that depending on the initial state the evolution can or cannot display indifferentiability points in its time-evolution (due to the energy conservation law), as well as non-trivial dependence on inter-qubit phase. Furthermore, we show that for initial Bell states, quantum correlations display a strong magnetic-field sensitivity which can be utilized for decoherence-driven measurements of the external magnetic field. The potential discord-based measurement is sensitive to a wider range of magnetic field values than the entanglement-based measurement. In principle, entanglement is not a necessary resource for reliable decoherence-driven measurement, while the presence of quantum correlations beyond entanglement is.

arXiv comment9 pages, 6 figures

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Cited by in corpus (7)

• Equivalence of qubit-environment entanglement and discord generation via pure dephasing interactions and the consequences thereof
• Dynamics of entanglement of two electron spins interacting with nuclear spin baths in quantum dots
• Theory of box-model hyperfine couplings and transport signatures of long-range nuclear-spin coherence in a quantum-dot spin valve
• The relation between the quantum discord and quantum teleportation: the physical interpretation of the transition point between different quantum discord decay regimes
• Qubit-environment entanglement outside of pure decoherence: hyperfine interaction
• The sudden change phenomenon of quantum discord
• Sharp transitions in low-number quantum dots Bayesian magnetometry