Tigran V. Shahbazyan

Ultrafast Coulomb-induced dynamics of quantum well magnetoexcitons

We study theoretically the ultrafast nonlinear optical response of quantum well excitons in a perpendicular magnetic field. We show that for magnetoexcitons 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 polarization characterized by exponential and power law decay of the FWM signal. We describe these regimes by deriving an analytical solution for the memory kernel of the two-exciton wave function in a strong magnetic field. For strong exciton-exciton interactions, the decay of the FWM signal is governed by an antibound resonance with an interaction-dependent decay rate. For weak interactions, the continuum of exciton-exciton scattering states leads to a long tail of the time-integrated FWM signal for negative time delays, which is described by the product of a power law and a logarithmic factor. By combining this analytic solution with numerical calculations, we study the crossover between the exponential and nonexponential regimes as a function of magnetic field. For attractive exciton-exciton interactions, we show that the time evolution of the FWM signal is dominated by biexcitonic effects.

Mesoscopic cooperative emission from a disordered system

We study theoretically the cooperative light emission from a system of

Coherent ultrafast optical dynamics of the Fermi-edge singularity

N\ensuremath{\gg}1

Size-dependent correlation effects in the ultrafast optical dynamics of metal nanoparticles

classical oscillators confined within a volume with spatial scale L much smaller than the radiation wavelength

Luminescence from highly excited nanorings: Luttinger liquid description

{\ensuremath{\lambda}}_{0}=2\ensuremath{\pi}c/{\ensuremath{\omega}}_{0}.

Many-body luminescence from nanorings at high excitation level

We assume that the oscillator frequencies are randomly distributed around a central frequency

Coulomb memory effects in the ultrafast dynamics of quantum well magnetoexcitons

{\ensuremath{\omega}}_{0}

Spin correlations in nonlinear optical spectroscopy of semiconductor quantum wells

with some characteristic width

Spin dynamics in nonlinear optical spectroscopy of Fermi sea systems

\ensuremath{\Omega}\ensuremath{\ll}{\ensuremath{\omega}}_{0}.

Many-Body Spin Correlations in Nonlinear Optical Spectroscopy

In the absence of disorder, that is,