75 research outputs found
Anderson localization of one-dimensional hybrid particles
We solve the Anderson localization problem on a two-leg ladder by the
Fokker-Planck equation approach. The solution is exact in the weak disorder
limit at a fixed inter-chain coupling. The study is motivated by progress in
investigating the hybrid particles such as cavity polaritons. This application
corresponds to parametrically different intra-chain hopping integrals (a "fast"
chain coupled to a "slow" chain). We show that the canonical
Dorokhov-Mello-Pereyra-Kumar (DMPK) equation is insufficient for this problem.
Indeed, the angular variables describing the eigenvectors of the transmission
matrix enter into an extended DMPK equation in a non-trivial way, being
entangled with the two transmission eigenvalues. This extended DMPK equation is
solved analytically and the two Lyapunov exponents are obtained as functions of
the parameters of the disordered ladder. The main result of the paper is that
near the resonance energy, where the dispersion curves of the two decoupled and
disorder-free chains intersect, the localization properties of the ladder are
dominated by those of the slow chain. Away from the resonance they are
dominated by the fast chain: a local excitation on the slow chain may travel a
distance of the order of the localization length of the fast chain.Comment: 31 pages, 13 figure
Kinetics of exciton photoluminescence in type-II semiconductor superlattices
The exciton decay rate at a rough interface in type-II semiconductor
superlattices is investigated. It is shown that the possibility of
recombination of indirect excitons at a plane interface essentially affects
kinetics of the exciton photoluminescence at a rough interface. This happens
because of strong correlation between the exciton recombination at the plane
interface and at the roughness. Expressions that relate the parameters of the
luminescence kinetics with statistical characteristics of the rough interface
are obtained. The mean height and length of roughnesses in GaAs/AlAs
superlattices are estimated from the experimental data.Comment: 3 PostScript figure
Inhomogeneous Broadening of Exciton Lines in Magneto-Optical Reflection from CdTe/CdMgTe Quantum Wells
An approach is proposed to determine parameters of homogeneous and
inhomogeneous broadening for reflection lines of quasi-two-dimensional excitons
in semiconductor quantum well structures. A phenomenological model is developed
taking into account fluctuations of the exciton energy which are expected to
cause inhomogeneous broadening of exciton reflectivity lines. This concept is
applied to magneto-optical studies of CdTe/(Cd,Mg)Te single quantum well
heterostructures containing a two-dimensional electron gas. By the analysis of
excitonic reflection spectra in magnetic fields the parameters of homogeneous
and inhomogeneous broadening of the exciton as well as their temperature
dependencies were obtained.Comment: 13 pages, 4 figure
Propagation of circularly polarized waves in one-dimensional bragg structures (magnetophotonic crystals)
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