Seminar "Coherence-Correlations-Complexity", Dept. of Theoretical Physics, Wrocław University of Technology
Sala 320a bud. A-1, Politechnika Wrocławska
The decay of quantum correlations in quantum dot spin qubits for magnetic field measurement
dr Katarzyna Roszak
Katedra Fizyki Teoretycznej Wydziału PPT Politechniki Wrocławskiej
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.
