Radiative cascades from charged semiconductor quantum dots

Abstract

We measured two-photon radiative cascades due to sequential recombination of quantum-dot confined electron-hole pairs in the presence of an additional spectator charge carrier. We use temporally resolved polarization sensitive intensity correlation measurements to fully characterize these radiative cascades. We identified direct, all optical cascades involving spin-blockaded intermediate states, and indirect cascades, in which nonradiative relaxation precedes the second radiative recombination. Our measurements provide spin dephasing rates of confined single carriers.

Excitation spectroscopy of single quantum dots at tunable positive, neutral, and negative charge states

“…These biexcitonic transitions were identified previously by time-resolved intensity correlation measurements. 21 Additional lines are identified as transitions related to a two-hole charged QD (X +2 ). These transitions present exactly the same resonances in their PLE spectra (not shown here), and thus we attribute them to emission lines that occur from the same initial state.…”

“…Based on previous studies, we unambiguously identify this spectral line as the optical transition from the ground state positive trion (X +1 ), (1e 1 )(1h 2 ) → (1h 1 ) to a single ground level heavy hole state. 21 In the initial state, the two holes form a singlet of spin 0 in their ground level. The total spin of this state is therefore given by the spin-half state of the singleelectron.…”

Exciton and multiexciton optical properties of single InAs/GaAs site-controlled quantum dots

“…9 In charged biexcitons several decay pathways are observed, some of them involving different intermediate states in the cascade and presenting a high degree of polarization correlations. 10 The use of hot trions enables the control of the spatial extent of carrier wavefunctions and the spin manipulation via optical pumping resonant to the P-Shell. 11,12 From these findings, it is concluded that the detailed knowledge of the QD electronic structure is required for the generation and management of multiparticle exciton species with interesting emission properties for quantum information technologies.…”

Exchange interaction-driven dynamic nuclear polarization in Mn-doped InGaAs/GaAs quantum dots

“…7(c). Note that under a fixed polarization detection (σ − here) there is a correlation between the h 1 ⇑ or ⇓ spin and the T +3 or T 0 triplet state 36 , which explains the position in positive or negative field of the corresponding X-pattern. Finally, the electron-hole exchange which also contributes to the triplet splitting ∆ T , determines with the electron-A 0 exchange, the electron spin splitting ∆ between the bright (| ± 1, T +3 , ↓ ) and dark (| ± 1, T +3 , ↑ ) configurations of X + as represented in Fig.…”