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

¹ Institute for Theoretical Physics and Astrophysics, University of Gdańsk - 80-952 Gdańsk, Poland
² National Quantum Information Centre of Gdańsk - 81-824 Sopot, Poland
³ Institute of Physics, Wrocław University of Technology - 50-370 Wrocław, Poland
⁴ Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University 12116 Prague, Czech Republic
⁵ Faculty of Applied Physics and Mathematics, Gdańsk University of Technology - 80-952 Gdańsk, Poland

Received: 27 June 2014
Accepted: 27 August 2014

Abstract

We address the question of the role of quantum correlations beyond entanglement in the context of quantum magnetometry. We study the evolution of the rescaled variant of the geometric quantum discord of two electron-spin qubits interacting with an environment of nuclear spins via the hyperfine interaction. We have found that quantum correlations display a strong magnetic-field sensitivity which can be utilized for decoherence-driven measurements of the external magnetic field. The discord-based measurement is sensitive to a wider range of magnetic-field values than the entanglement-based measurement, including very small fields which are inaccessible via entanglement.