12 research outputs found
Theory of combined exciton-cyclotron resonance in a two-dimensional electron gas: The strong magnetic field regime
I develop a theory of combined exciton-cyclotron resonance (ExCR) in a
low-density two-dimensional electron gas in high magnetic fields. In the
presence of excess electrons an incident photon creates an exciton and
simultaneously excites one electron to higher-lying Landau levels. I derive
exact ExCR selection rules that follow from the existing dynamical symmetries,
magnetic translations and rotations about the magnetic field axis. The nature
of the final states in the ExCR is elucidated. The relation between ExCR and
shake-up processes is discussed. The double-peak ExCR structure for transitions
to the first electron Landau level is predicted.Comment: 5 pages, 3 figures, replaced with the published versio
Charged hydrogenic problem in a magnetic field: Non-commutative translations, unitary transformations, and coherent states
An operator formalism is developed for a description of charged electron-hole
complexes in magnetic fields. A novel unitary transformation of the Hamiltonian
that allows one to partially separate the center-of-mass and internal motions
is proposed. We study the operator algebra that leads to the appearance of new
effective particles, electrons and holes with modified interparticle
interactions, and their coherent states in magnetic fields. The developed
formalism is used for studying a two-dimensional negatively charged
magnetoexciton . It is shown that Fano-resonances are present in the
spectra of internal transitions, indicating the existence of
three-particle quasi-bound states embedded in the continuum of higher Landau
levels.Comment: 9 pages + 2 figures, accepted in PRB, a couple of typos correcte
Shake-up Processes in a Low-Density Two-Dimensional Electron Gas: Spin-Dependent Transitions to Higher Hole Landau Levels
A theory of shake-up processes in photoabsorption of an interacting
low-density two-dimensional electron gas (2DEG) in strong magnetic fields is
presented. In these processes, an incident photon creates an electron-hole pair
and, because of Coulomb interactions, simultaneously excites one particle to
higher Landau levels (LL's). In this work, the spectra of correlated charged
spin-singlet and spin-triplet electron-hole states in the first hole LL and
optical transitions to these states (i.e., shake-ups to the first hole LL) are
studied. Our results indicate, in particular, the presence of optically-active
three-particle quasi-discrete states in the exciton continuum that may give
rise to surprisingly sharp Fano resonances in strong magnetic fields. The
relation between shake-ups in photoabsorption of the 2DEG and in the 2D hole
gas (2DHG), and shake-ups of isolated negative X^- and positive X^+ trions are
discussed.Comment: 8 pages, 8 figures. References updated, one figure added (Fig. 6).
Accepted in Phys. Rev.
δ-TRIMAX: Extracting Triclusters and Analysing Coregulation in Time Series Gene Expression Data
The influence of environmental factors, the pollen : ovule ratio and seed bank persistence on molecular evolutionary rates in plants
Consumo alimentar de adolescentes matriculados em um colégio particular de Teresina, Piauí, Brasil
“Come Then Ye Classic Thieves of Each Degree”: The Social Context of the Persepolis Diaspora in the Early Nineteenth Century
The diaspora of fragments from the stone structures on the Persepolis terrace in Iran began in earnest in the early nineteenth century. Members of the embassy of Sir Gore Ouseley made the best-known collections in 1811. This paper sets these removals in the context of a broader series of British physical interventions and transactions between 1800 and 1828. Fragments moved within a gift economy operating between detachments of East India Company officers who were deployed in Qajar-ruled Persia in order to control the Persian Gulf and the overland route to Europe. Archival research has enabled the reconstruction of object biographies for three fragments in London and Edinburgh, and for several other fragments whose present location is not known to me. The case study contributes to our knowledge of the overall rate of the dispersal of carved relief from the site. Acquisitions of architectural fragments from the site accelerated significantly in the twentieth century; the patterns of removal in the nineteenth century reflect the difficult and variable prevailing conditions.</p