Rabi oscillation damping of two-level states in quantum dots

Mogilevtsev, D.; Nisovtsev, A.P.; Kilin, S. Ya.; Cavalcanti, S. B.; Brandi, H. S.; Oliveira, L. E.

doi:10.1016/j.physe.2007.09.057

Cited by 3 publications

(3 citation statements)

References 7 publications

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“…For the trion and donor-bound exciton heating of the electronic ensemble in the ground state is also one of the relevant mechanisms [30]. Nevertheless, it has been shown that the concrete mechanism is less important than the non-Markovian behavior of a reservoir [31,32]. Here, we assume that for our conditions the intensity-dependence of the dephasing rate is governed by excitation-induced dephasing (EID) [20,21].…”

Section: Pacs Numbersmentioning

confidence: 99%

Damping of Rabi oscillations in intensity-dependent photon echoes from exciton complexes in a CdTe/(Cd,Mg)Te single quantum well

et al. 2017

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We study Rabi oscillations detected in the coherent optical response from various exciton complexes in a 20 nm-thick CdTe/(Cd,Mg)Te quantum well using time-resolved photon echoes. In order to evaluate the role of exciton localization and inhomogeneous broadening we use selective excitation with spectrally narrow ps-pulses. We demonstrate that the transient profile of the photon echo from the localized trion (X − ) and the donor-bound exciton (D 0 X) transitions strongly depends on the strength of the first pulse. It acquires a non-Gaussian shape and experiences significant advancement for pulse areas larger than π due to non-negligible inhomogeneity-induced dephasing of the oscillators during the optical excitation. Next, we observe that an increase of the area of either the first (excitation) or the second (rephasing) pulse leads to a significant damping of the photon echo signal, which is strongest for the neutral excitons and less pronounced for the donor-bound exciton complex (D 0 X). The measurements are analyzed using a theoretical model based on the optical Bloch equations which accounts for the inhomogeneity of optical transitions in order to reproduce the complex shape of the photon echo transients. In addition, the spreading of Rabi frequencies within the ensemble due to the spatial variation of the intensity of the focused Gaussian beams and excitation-induced dephasing are required to explain the fading and damping of Rabi oscillations. By analyzing the results of the simulation for the X − and the D 0 X complexes we are able to establish a correlation between the degree of localization and the transition dipole moments determined as µ(X − )=73 D and µ(D 0 X)=58 D. PACS numbers:Introduction. Coherent control of excitonic states in semiconductor nanostructures under resonant excitation with intense optical pulses attracts a lot of attention in relation with possible applications in quantum information [1]. These ideas exploit coherent rotations of the Bloch vector in the photoexcited two-level system (TLS), which depends on the area of the exciting pulse via Rabi oscillations [2][3][4]. Since stronger localization of excitons is in favor of longer decoherence times, most of the studies of coherent control have concentrated on quantum dots (QD) [3,5,6]. However, the strong localization in QDs is accompanied by large variations in QD size, shape, and composition which consequently leads to the large inhomogeneous broadening of the optical transitions when an ensemble of emitters is used. Therefore, most Rabi oscillation studies were performed on single QDs [7-10].In semiconductor quantum well (QW) structures the inhomogeneous broadening of the optical transitions is significantly smaller as compared to QD systems, i.e. it is possible to selectively address different exciton complexes, such as free and localized excitons, localized charged excitons (trions, X − ), and donor-bound excitons (D 0 X). Therefore, QW structures can be considered as a model system for the investigation of Rabi oscillations and t...

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Section: Pacs Numbersmentioning

confidence: 99%

Damping of Rabi oscillations in intensity-dependent photon echoes from exciton complexes in a CdTe/(Cd,Mg)Te single quantum well

et al. 2017

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“…Other non-Markovian processes of Rabi oscillation damping in driven quantum dots are considered in Ref. [32]. For the sake of simplicity, we assume a point-like character of localized wavefunctions 9LS ¼ ð90Sþ 91SÞ= ffiffiffi 2 p and 9RS ¼ ð90SÀ 91SÞ= ffiffiffi 2 p in the left and the right dot in Fig.…”

Section: Qubit Evolutionmentioning

confidence: 99%

Effect of image charge on double quantum dot evolution

Filippov

Vyurkov

Fedichkin

2011

Physica E: Low-dimensional Systems and Nanostructures

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“…We will invoke the ionization energy theory (IET) to analyze how different elemental compositions in QDs and substrate will give rise to pure or inelastic dephasing processes or both. The reasons for incorporating the elemental compositions in QDs and substrate are (1) to investigate the reports that claim the matrix and/or substrate are indeed influencing both the electronic and phononic properties of the QDs [20,21,22,23,24], and (2) to develop a strategy based on the IET to distinguish the contradicting results obtained by Sanguinetti et al [2] and others: Zibik et al [5,25] and Chernikov et al [26]. For example, pure dephasing was found to be responsible in GaAs QDs on Al 0.3 Ga 0.7 As substrate [2].…”

Section: Introductionmentioning

confidence: 99%

Controlling electronic and adiabatic isolation of quantum dots from the substrate: An ionization-energy theoretic study

Arulsamy¹,

Ostrikov²

2010

Physica B: Condensed Matter

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Recent controversy on the quantum dots dephasing mechanisms (between pure and inelastic) is re-examined by isolating the quantum dots from their substrate by using the appropriate limits of the ionization energy theory and the quantum adiabatic theorem. When the phonons in the quantum dots are isolated adiabatically from the phonons in the substrate, the elastic or pure dephasing becomes the dominant mechanism. On the other hand, for the case where the phonons from the substrate are non-adiabatically coupled to the quantum dots, the inelastic dephasing process takes over. This switch-over is due to different elemental composition in quantum dots as compared to its substrate. We also provide unambiguous analyses as to understand why GaAs/AlGaAs quantum dots may only have pure dephasing while InAs/GaAs quantum dots give rise to the inelastic dephasing as the dominant mechanism. Our study accentuates the importance of the elemental composition (of both quantum dots and substrate) in evaluating the dephasing mechanisms of quantum dots.

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Rabi oscillation damping of two-level states in quantum dots

Cited by 3 publications

References 7 publications

Damping of Rabi oscillations in intensity-dependent photon echoes from exciton complexes in a CdTe/(Cd,Mg)Te single quantum well

Damping of Rabi oscillations in intensity-dependent photon echoes from exciton complexes in a CdTe/(Cd,Mg)Te single quantum well

Effect of image charge on double quantum dot evolution

Controlling electronic and adiabatic isolation of quantum dots from the substrate: An ionization-energy theoretic study

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