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(Color online) Temporal evolution of the population of the QD electron (solid line) and hole (dotted line) ground state being partially inverted by differently chirped (, , and ) 8π pulses at a temperature of 77 K. The results are compared with a two-level system (dashed line) for which energy renormalization is considered, but carrier scattering and dephasing due to LO phonons is neglected. The latter clearly reduces the inversion in the QD system for small chirp rates.
(Color online) Excitation scheme with QDs and p-shell interband transitions (solid lines) and carrier frequency of three different chirped excitation pulse. At the temporal maximum of the pulse envelope (dashed dotted line) the pulses are in resonance with the s-shell transition. Different chirp rates correspond to Fig. 1 (long dashed , short dashed , dotted ). For the largest chirp rate, also the p-transition is excited.
(Color online) Resulting inversion versus pulse frequency at peak intensity for a two-level system (dashed line) and QD ground state (solid line) (pulse area = 6π, ). The dashed-dotted line shows the QD ground state without carrier scattering but with dephasing due to carrier-LO-phonon interaction. A high degree of inversion is possible with a single pulse for QDs with very different transition energies.
(Color online) Inversion of the QD ground state as a result of a resonant (solid line) or chirped (dotted and dashed lines) 200fs pulse versus its unrenormalized pulse area: While there is an oscillatory dependency for the resonant pulse, the inversion caused by a chirped pulse depends only slightly on its pulse area. With increasing chirp rate (long dashed , short dashed , dotted ) the influence of the dephasing is reduced and therefore the inversion is increased.
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