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Axt, Vollrath Martin ; Krummheuer, B. ; Vagov, Alexei ; Kuhn, Tilmann:
Analytical results for nonlinear optical signals from quantum dots coupled to phonons.
In: Physica Status Solidi B.
Bd. 238
(2003)
Heft 3
.
- S. 581-588.
ISSN 1521-3951
DOI: https://doi.org/10.1002/pssb.200303175
Angaben zu Projekten
| Projektfinanzierung: |
European Commission within the Future and Emerging Technologies (FET) project IST-1999-11311 (Semiconductor-based Implementation of Quantum Information Devices) |
|---|
Abstract
The impact of pure dephasing processes on the optically induced nonlinear dynamics of quantum dots is analyzed. Concentrating on small dots pure dephasing can be studied analytically in the limit of ultrafast excitation. General conclusions from the analysis of the closed form formulas include the prediction that four-wave-mixing (FWM) spectra of single dots change from asymmetric to symmetric lineshapes with increasing pulse delay. Furthermore, in contrast to phenomenological dephasing models the delay dependence of the time integrated FWM amplitude |PFWM| generated by a strongly inhomogeneously broadened ensemble deviates from the real time dependence of |Plin|2, where Plin is the linear polarization emitted by a single dot. Numerical results are presented for FWM signals from dots coupled to bulk acoustic phonons. Surprisingly, the initial decay time of the signal depends non-monotonously on the temperature. In addition, it is shown that for certain material parameters the coupling to the smooth continuum of acoustic phonons may result in pronounced oscillations.