Dark-bright exciton coupling in asymmetric quantum dots

Abstract

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Electrical control of optically pumped electron spin in a single GaAs/AlAs quantum dot fabricated by nanohole infilling

“…The optical activity of the dark spin configuration exciton results from the low C s symmetry of the QD confinement potential [9,28,29]. This symmetry breaking is taken into account in the effective Hamiltonian by adding new contributions toĤ eeh in Eq.…”

“…This symmetry breaking is taken into account in the effective Hamiltonian by adding new contributions toĤ eeh in Eq. (1) [9,28] as…”

Emission properties and temporal coherence of the dark exciton confined in a GaAs/AlxGa1−xAs quantum dot

“…This requires a strong reduction of the symmetry to C s symmetry, for which the twofold rotational invariance is lost, while only a single mirror symmetry containing the growth axis remains [16]. The dark-bright mixing Hamiltonian can be rewritten as [17,18]…”

“…where | ± 1 = |s e z = ∓1/2; 3/2, ±3/2 and | ± 2 = |s e z = ±1/2; 3/2, ±3/2 . In the framework of the effective-mass approximation and only taking into account Coulomb correlations for the lower-energy single-particle states, we have previously shown that the amplitudes of the dark-bright exciton mixing terms 11 and 12 are proportional to the magnitude of the VBM parameter γ [17]. We have also studied the effect of the dark-bright exciton coupling on excited multicharged excitonic complexes whose dark spin configurations have shown a detectable level of absorption [19].…”

“…In InAs/GaAs QDs and CdTe/ZnTe QDs, biaxial strain and shear strain dominate significantly to the magnitude of the VBM parameters β and γ , respectively [12,17]. In the case of strain-free QDs, several mechanisms have been proposed to explain the VBM observed with no single mechanism dominating the magnitude of the VBM.…”