Qi-Jun Zeng

Velocity-controlled guiding of electron in graphene: Analogy of optical waveguides

Motivated by the realization of the Dirac point with tunable Fermi velocity in low-dimensional systems, we investigate the guided modes in graphene waveguides corresponding to the electron motion (or the hole motion) in a symmetric velocity barrier. We find that the fundamental mode always exists, but the higher-order mode may disappear. These discrete guided modes imply that there is a lowest cutoff frequency for an incident electron and that the incident electrons with different angles may have different minimum cutoff frequencies. These interesting features will be helpful for the investigation on an electronic fiber.

Fluctuations of a q-deformed boson gas

Within the framework of the theory of q-deformed bosons, we investigate the problem of fluctuations of a q-deformed boson system, and obtain the general result for thermodynamic fluctuations of such a system. Especially, for the system of a q-deformed boson gas, we get the expressions for the fluctuations of internal energy U and particle number N, and the correlation of the fluctuations of the two physical quantities above. Further numerical calculation shows that the fluctuations of such a q-deformed boson gas have some interesting features. We consider that this work may provide much insight into the theory of q bosons, and may also be useful for the further study of a concrete q-deformed boson gas.