The dynamics of excitation energy transfer within the B850 ring of light harvesting complex 2 from Rhodobacter sphaeroides and between neighboring B850 rings is investigated by means of dissipative quantum mechanics. The assumption of Boltzmann populated donor states for the calculation of intercomplex excitation transfer rates by generalized Forster theory is shown to give accurate results sin...

We study the slow-light performance in the presence of exciton-exciton interaction in films of linear molecular aggregates at the nanometer scale. In particular, we consider a four-level model to describe the creation/annihilation of two-exciton states that are relevant for high-intensity fields. Numerical simulations show delays comparable to those obtained for longer propagation distances in ...

We studied the temperature and excitation intensity dependence of exciton luminescence in individual single-walled carbon nanotubes (SWNTs) using single nanotube photoluminescence (PL) spectroscopy. The linear temperature dependence of the PL linewidth in a single SWNT implies that the exciton dephasing is dominated by the interaction between the exciton and the phonon mode with very low energy...

We have studied the quasi-two-dimensional exciton in ZnSe/ZnxMg12xSySe12y ~x50.85, y50.21! single quantum wells ~SQWs! by photoluminescence and photoluminescence excitation spectroscopy. Self-consistent calculations of the peak energies for a series of SQWs give the conduction band discontinuity DEc50.40DEg and the binding energy of the n51 heavy-hole exciton Eb~hh1!522.1 meV for an 8 nm well w...

2014 We report the spectral and time characteristics of the fluorescence of CsMnF3. The weak intrinsic fluorescence in nominally pure samples is analysed with time resolved techniques showing the energy transfer processes from exciton to fluorescing traps. By applying either a uniaxial stress along the Mn2-Mn1 direction or a high magnetic field in the basal plane we are able to monitor the effi...

With the exciton lifetime much extended in semiconductor quantum-well structures, the exciton transport and Bose-Einstein condensation have become a focus of research in recent years. We reveal a momentum-space gauge field in the exciton center-of-mass dynamics due to Berry phase effects. We predict a spin-dependent transport of the excitons analogous to the anomalous Hall and Nernst effects fo...

We study theoretically the ultrafast nonlinear optical response of quantum well excitons in a perpendicular magnetic field. We show that for magnetoex-citons confined to the lowest Landau levels, the third-order four-wave-mixing (FWM) polarization is dominated by the exciton-exciton interaction effects. For repulsive interactions, we identify two regimes in the time-evolution of the optical pol...

The variational results for the free energy of an interacting exciton phonon system are used to derive expressions for the scattering rate and diffusion constant of an exciton in such a system. These expressions are applicable to both wide and narrow band cases, and includes the possibility of an abrupt transition from wide band (free) exciton to narrow band (localized) exciton. Some comments a...

We studied exciton structures and the Aharonov-Bohm effect in a single carbon nanotube using micro-photoluminescence (PL) spectroscopy under a magnetic field at low temperatures. A single sharp PL peak from the bright exciton state of a single carbon nanotube was observed under zero magnetic field, and the additional PL of dark exciton state appeared below the bright exciton peak under high mag...

Unlike conventional photon lasing, in which the threshold is limited by the population inversion of the electron-hole plasma, the exciton lasing generated by exciton-exciton scattering and the polariton lasing generated by dynamical condensates have received considerable attention in recent years because of the sub-Mott density and low-threshold operation. This paper presents a novel approach t...