title: Optical properties of Dirac electrons in a parabolic well.
abstract: A single electron transitor may be fabricated using qunatum dots. A good model for the confinement potential of a quantum dot is a parabolic well. Here we consider such a parabolic dot made of graphene. Recently, we found counter intuitively that resonant quasi-boundstates of both positive and negative energies exist in the energy spectrum. The presence of resonant quasi-boundstates of negative energies is a unique property of massless Dirac fermions. As magnetic field B gets smaller the energy width of these states become broader and for sufficiently weak value of B resonant quasi-bound states disappear into a quasi-continuum. In the limit of small B resonant and nonresonant states transform into discrete anomalous states with a narrow probability density peak inside the well and another broad peak under the potential barrier. In this paper we compute the optical strength between resonant quasi-bound states as a function of B, and investigate how the signature of resonant quasi-bound states of Dirac electrons may appear in optical measurements.
authors.affiliation: Physics Department, College of Science, Korea University, Seoul 136-713, Korea.
authors.forename: S C
authors.initials: SC
authors.lastname: Kim
authors.forename: J W
authors.initials: JW
authors.lastname: Lee
authors.forename: S-R Eric
authors.initials: SR
authors.lastname: Yang