Optical study of electron-electron exchange interaction in CdTe/ZnTe quantum dots

Kazimierczuk, T.; Smoleński, T.; Kobak, J.; Goryca, M.; Pacuski, W.; Golnik, A.; Fronc, K.; Kłopotowski, Ł.; Wojnar, P.; Kossacki, P.

doi:10.1103/physrevb.87.195302

Cited by 16 publications

(13 citation statements)

References 22 publications

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“…We find 2J ee to be around 18meV, in very good agreement with the data reported in Ref. 17. Note that the ratio between the amplitudes of the absorption peaks for singlet (B (2) sp,0 ) and triplet (B sp,0 ) biexcitons is around 0.5, as observed in experiment 17 .…”

Section: B All-optical Manipulation Of Sp Biexcitonssupporting

confidence: 92%

“…17. Note that the ratio between the amplitudes of the absorption peaks for singlet (B (2) sp,0 ) and triplet (B sp,0 ) biexcitons is around 0.5, as observed in experiment 17 . In Fig.…”

Section: B All-optical Manipulation Of Sp Biexcitonssupporting

confidence: 64%

“…17) being much larger than for InAs/GaAs QDs (few meV). In the latter case one can argue 20 that if the pulse width exceeds the singlet-triplet splitting the exchange interaction effects are washed out.…”

Section: B All-optical Manipulation Of Sp Biexcitonsmentioning

confidence: 84%

“…Let us mention here that the triplet state measured in Ref. (17) appears only if the initial QD state is an excited one: there are two extra electrons in the conduction band and no holes (full valence band). In our setup the initial state is the ground state (empty conduction band and full valence band) which allows a better control over the fast initialization of the triplet state.…”

Section: B All-optical Manipulation Of Sp Biexcitonsmentioning

confidence: 89%

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Dynamics and relaxation ofspbiexcitons in disk-shaped quantum dots

2014

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We study the effects of intraband relaxation processes on optical manipulation protocols for sp biexcitons hosted by CdTe disk-shaped quantum dots. The many-body states are calculated within the configuration interaction method starting from single-particle states given by the k · p theory. The time-dependent occupations of relevant many-body states are extracted from the von NeumannLindblad equation for the density operator. We mainly investigate the generation of sp biexcitons with two pulses of different polarizations σ+ and σ−. The fast hole relaxation processes prevent a high-fidelity controlled operation on sp biexcitons and lead to the occupation of some transient states which can be optically probed. More importantly, the many-body structure of the transient states consists of two holes on the s shell and antiparallel sp triplet states for electrons. Our simulations show that these triplet states are more stable against decoherence as they can only be damaged through slow electron relaxation. The configuration mixing due to correlation effects is also discussed.

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Section: B All-optical Manipulation Of Sp Biexcitonssupporting

confidence: 92%

“…17. Note that the ratio between the amplitudes of the absorption peaks for singlet (B (2) sp,0 ) and triplet (B sp,0 ) biexcitons is around 0.5, as observed in experiment 17 . In Fig.…”

Section: B All-optical Manipulation Of Sp Biexcitonssupporting

confidence: 64%

Section: B All-optical Manipulation Of Sp Biexcitonsmentioning

confidence: 84%

Section: B All-optical Manipulation Of Sp Biexcitonsmentioning

confidence: 89%

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Dynamics and relaxation ofspbiexcitons in disk-shaped quantum dots

2014

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“…Large confinement potentials and strong Coulomb interactions, which follow from a reduced dielectric screening, lead to charge and spin configurations with larger separations between quantized energy levels as compared to their III-V counterparts [32][33][34][35]. This fact enables ultrafast quantum manipulation with broadband laser pulses.…”

Section: Introductionmentioning

confidence: 99%

Charge and spin control of ultrafast electron and hole dynamics in single CdSe/ZnSe quantum dots

et al. 2018

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We study the dynamics of photoexcited electrons and holes in single negatively charged CdSe/ZnSe quantum dots with two-color femtosecond pump-probe spectroscopy. An initial characterization of the energy level structure is performed at low temperatures and magnetic fields of up to 5 T. Emission and absorption resonances are assigned to specific transitions between few-fermion states by a theoretical model based on a configuration interaction approach. To analyze the dynamics of individual charge carriers, we initialize the quantum system into excited trion states with defined energy and spin. Subsequently, the time-dependent occupation of the trion ground state is monitored by spectrally resolved differential transmission measurements. We observe subpicosecond dynamics for a hole excited to the D shell. The energy dependence of this D-to-S shell intraband transition is investigated in quantum dots of varying size. Excitation of an electron-hole pair in the respective p shells leads to the formation of singlet and triplet spin configurations. Relaxation of the p-shell singlet is observed to occur on a time scale of a few picoseconds. Pumping of p-shell triplet transitions opens up two pathways with distinctly different scattering times. These processes are shown to be governed by the mixing of singlet and triplet states due to exchange interactions enabling simultaneous electron and hole spin flips. To isolate the relaxation channels, we align the spin of the residual electron by a magnetic field and employ laser pulses of defined helicity. This step provides ultrafast preparation of a fully inverted trion ground state of the quantum dot with near unity probability, enabling deterministic addition of a single photon to the probe pulse. Therefore our experiments represent a significant step towards using single quantum emitters with well-controled inversion to manipulate the photon statistics of ultrafast light pulses.

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