Thermal free entanglement of π-electronic spin and Landau-sublattice states in Rashba monolayer graphene

Abstract

Free entanglement-the milestone of any quantum information processing scheme-among the π-electronic spin and its spatial states in graphene, as a function of temperature, is the main concern of the present report. It is assumed that a perpendicular magnetic field generates the Landau levels so that a coupling with the pseudo-spin (sublattice) states is enacted. Moreover, the pseudo-Rashba spin-orbit interaction (SOI), responsible for the coupling of spin and sublattice states, is also taken into account. From the structure of the total Hamiltonian, we introduce a Casimir operator which, in due turn, assists the development of a simple but ecient algorithm for our numerical computation. We then proceed by constructing the thermal density operator, its partially transposed one and, thereby, compute the negativity, the proper measure of free hybrid entanglement, at any temperature. Our results show that the negativity is nonvanishing at absolute zero temperature due to the fact that the ground state is an entangled one. Moreover, our results indicate that the negativity, at certain temperatures, exhibits maxima. The temperatures at which the entanglement (free) is maximal strongly depend on the magnetic field and pseudo-Rashba spin-orbit strength; decreasing the magnetic field and/or increasing the pseudo-Rashba parameter (PRP) enhances the maximal entanglement monotonically. As the temperature increases, however, it is shown that the negativity decreases asymptotically to zero. As a result, there exists distillable entanglement amid the π-electronic spin and its spatial states in graphene at any finite temperature.

Graphene Decorated with Silver Nanoparticles as a Low-Temperature Methane Gas Sensor

“…The former may be generated by decorating graphene sheets with elements of specific characteristics. Although it is not of concern in the present report, we may mention that the internal ones are formed mostly by the well-known Rashba spin–orbit interaction. − In graphene, moreover, the ratio of area to volume (due to negligible thickness) is very high and thus the probability of getting in contact with gas molecules becomes large. ,, It has also been well established that electric signals in graphene are almost noise-free (because of almost perfect crystalline structure) ,, so that signal-to-noise ratio in current measurements is high. We also note that at low temperatures, the gas sensing mechanism of graphene is in fact a physical adsorption type, ,, making it a reversible and repeatable sensing device.…”

Characteristics of the Temporal Behavior of Entanglement between Photonic Binomial Distributions and a Two-Level Atom in a Damping Cavity

“…This demeanor is physically due to the fact that an increase in the temperature gives rise to the excitation of more atom-photon states with almost equal probabilities. In the limit of extremely high temperatures, they become exactly equal and the system approaches a fully mixed state, with no entanglement [32]. For illustration of the finer detail of entanglement between atoms and binomial photonic states in a lossy cavity, we present Figs.…”