Herbert Vinck-Posada

Characterization of dynamical regimes and entanglement sudden death in a microcavity quantum dot system

The relation between the dynamical regimes (weak and strong coupling) and entanglement for a dissipative quantum dot microcavity system is studied. In the framework of a phenomenological temperature model an analysis in both temporal (population dynamics) and frequency domain (photoluminescence) is carried out in order to identify the associated dynamical behavior. The Wigner function and concurrence are employed to quantify the entanglement in each regime. We find that sudden death of entanglement is a typical characteristic of the strong coupling regime.

Photon emission as a source of coherent behavior of polaritons.

We show that the combined effect of photon emission and Coulomb interactions may drive an exciton-polariton system towards a dynamical coherent state, even without phonon thermalization or any other relaxation mechanism. Exact diagonalization results for a finite system (a multilevel quantum dot interacting with the lowest-energy photon mode of a microcavity) are presented in support of this statement.

Polariton lasing in a multilevel quantum dot strongly coupled to a single photon mode

We present an approximate analytic expression for the photoluminescence spectral function of a model polariton system, which describes a quantum dot, with a finite number of fermionic levels, strongly interacting with the lowest photon mode of a pillar microcavity. Energy eigenvalues and wave functions of the electron-hole-photon system are obtained by numerically diagonalizing the Hamiltonian. Pumping and photon losses through the cavity mirrors are described with a master equation, which is solved in order to determine the stationary density matrix. The photon first-order correlation function, from which the spectral function is found, is computed with the help of the quantum regression theorem. The spectral function qualitatively describes the polariton lasing regime in the model, corresponding to pumping rates two orders of magnitude lower than those needed for ordinary (photon) lasing. The second-order coherence functions for the photon and the electron-hole subsystems are computed as functions of the pumping rate.

Classical modelling of the fourth-order spatial coherence state of scalar wave-fields

The fourth-order spatial coherence state of wave-fields is described in the framework of the classical wave picture, by means on the four-order spatial coherence wavelets. This strategy suggests that the fourth-order spatial coherence state of light can be modelled in terms of three layers of point sources in order to increase the performance of numerical algorithms. The model is illustrated by applying it to the Hanbury-Brown & Twiss effect.

Micropillar resonator in a magnetic field: Zero and finite temperature cases

Abstract In this work, we present a theoretical study of a quantum dot–microcavity system which includes a constant magnetic field in the growth direction of the micropillar. First, we study the zero temperature case by means of a self-consistent procedure with a trial function composed of a coherent photon field and a BCS function for the electron–hole pairs. The dependence of the ground state energy on the magnetic field and the number of polaritons is found. We show that the magnetic field can be used as a control parameter for the photon number, and we make explicit the scaling of the total energy with the number of polaritons. Next, we study this problem at finite temperatures and obtain the scaling of the critical temperature with the number of polaritons.

Wigner function and decoherence in a microcavity-Qdot system

The relation between the master equation and the Wigner function to characterize the dissipative system dynamics (evolution, mixedness and decoherence) between a three-level quantum-dot system coupled with two light modes in a semiconductor microcavity is analyzed. In particular, it is shown that the dephasing processes increase the decoherence driving the system from the strong coupling to the weak coupling regime.