Decoherence and maintenance of an entangled state in three-spin system coupled to ferromagnetic electrodes

• Published in: Physica. B, Condensed matter Condensed matter, 2022-12, Vol.646, p.414297, Article 414297
• Main Authors: Kim, Chang-Il, Kim, Nam-Chol, Yun, Chol-Song, Kang, Chol-Jin
• Format: Article
• Language: English
• Subjects: Born-Markov master equation; Decoherence of entangled state; Ferromagnetic electrodes; Three-spin system
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2022.414297

We study the model of three-spin system by using Born-Markov master equation for density matrix. Three-spin system consists of a spin-1/2 quantum dot and two spin-1 magnetic particles arranged in triangular geometry and a quantum dot is also tunnel-coupled to ferromagnetic electrodes, respectively. In this case, we are interested in decoherence of entangled state of the system. Decoherence occurs due to tunneling of electrons through coupling to ferromagnetic electrodes. Therefore, an entangled state undergoes decoherence dependent on the spin polarization as well as magnetization orientations of electrodes. We have established master-equation formalism for the density matrix of three-spin system and calculated spin-spin correlation function between two magnetic particles corresponding to entangled state. The results show that with the increase of spin polarization, spin-spin correlation function for parallel configuration of electrodes’ magnetizations decays more rapidly, while spin-spin correlation function for antiparallel configuration decays more slowly.