Entanglement of electronic subbands and coherent superposition of spin states in a Rashba nanoloop

• Published in: The European physical journal. B, Condensed matter physics Vol. 83; no. 4; pp. 457 - 463
• Main Authors: Safaiee, R., Golshan, M. M.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.10.2011; EDP Sciences; Springer
• Subjects: Analysis; Complex Systems; Condensed Matter Physics; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic structure of nanoscale materials : clusters, nanoparticles, nanotubes, and nanocrystals; Exact sciences and technology; Fluid- and Aerodynamics; Magnetic fields; Physics; Physics and Astronomy; Regular Article; Solid State Physics; Coherent Superposition; Density Operator; Time Evolution Operator; Electronic Spin State; Spin State; Time dependence; Rashba effect; Electronic structure; Hamiltonians; High field; Magnetic field effects; Spin-orbit interactions; Oscillations; Entangled states; Numerical method; Subband
• ISSN: 1434-6028; 1434-6036
• DOI: 10.1140/epjb/e2011-20142-x

The present work is concerned with an analysis of the entanglement between the electronic coherent superpositions of spin states and subbands in a quasi-one-dimensional Rashba nanoloop acted upon by a strong perpendicular magnetic field. We explicitly include the confining potential and the Rashba spin-orbit coupling into the Hamiltonian and then proceed to calculate the von Neumann entropy, a measure of entanglement, as a function of time. An analysis of the von Neumann entropy demonstrates that, as expected, the dynamics of entanglement strongly depends upon the initial state and electronic subband excitations. When the initial state is a pure one formed by a subband excitation and the z-component of spin states, the entanglement exhibits periodic oscillations with local minima (dips). On the other hand, when the initial state is formed by the subband states and a coherent superposition of spin states, the entanglement still periodically oscillates, exhibiting stronger correlations, along with elimination of the dips. Moreover, in the long run, the entanglement for the latter case undergoes the phenomenon of collapse-revivals. This behaviour is absent for the first case of the initial states. We also show that the degree of entanglement strongly depends upon the electronic subband excitations in both cases.