Near-field spectra of quantum well excitons with non-Markovian phonon scattering

Abstract

The excitonic absorption spectrum for a disordered quantum well in presence of exciton-acoustic phonon interaction is treated beyond the Markov approximation. Realistic disorder exciton states are taken from a microscopic simulation, and the deformation potential interaction is implemented. The exciton Green's function is solved with a self energy in second order Born approximation. The calculated spectra differ from a superposition of Lorentzian lineshapes by enhanced inter-peak absorption. This is a manifestation of pure dephasing which should be possible to measure in near-field experiments.

Dephasing of excitons and multiexcitons in undoped andp-doped InAs/GaAs quantum dots-in-a-well

“…20,32,33 The phonon band increases its weight with decreasing size of the QD exciton 20 and is typically insignificant in exciton weakly confined by the lateral disorder in quantum wells. 34,35 The measured acoustic-phonon assisted decay time 17 T ph = ͱ ln 2 / ph , after which the phonon-assisted FWM ͓the term exp͑− 2 ph 2 ͒ in Eq. ͑1͔͒ has halved, is shown in Fig.…”

Enhancement of microcavity polariton relaxation under confinement

“…The matrix elements t ͑j,n͒,͑j Ј ,n Ј ͒ q involve the excitonic wave functions and are given by 22 t ͑j,n͒,͑jЈ,nЈ͒…”

“…A is the phonon quantization area, u s is the sound velocity, Accounting for the phonon coupling within the Markovian approximation, and for the finite lifetime, the rate equations for the populations N j,n = ͗p j,n † p j,n ͘ in the different polariton states ͑j , n͒ are 13,22 …”

Echo peak-shift spectroscopy of non-Markovian exciton dynamics in quantum wells

“…Migration of localized QW excitons has been studied a great deal, both experimentally 10,17,21-23 and theoretically. 15,24 At low temperatures, the migration of localized excitons has been shown to be dominated by acoustic-phonon-assisted exciton migration, [21][22][23] as predicted by theory, 24 with migration times of 10-100 ps. Here, a simple spectral diffusion model is used to describe this exciton migration.…”

“…12 There are many theoretical predictions of memory effects in bulk semiconductor and QW exciton systems, primarily due to non-Markovian interactions with acoustic and optical phonons. [13][14][15] Memory effects in bulk GaAs due to LO-phonon interactions are illustrated by the observation of oscillations in the time-integrated FWM signal. 16 In QWs, memory effects in the exciton-acoustic phonon interaction are inferred from FWM experiments, 17,18 but these experiments do not directly characterize the correlation function.…”