Exciton lifetime in InAs/GaAs quantum dot molecules

Abstract

The exciton lifetimes $T_1$ in arrays of InAs/GaAs vertically coupled quantum dot pairs have been measured by time-resolved photoluminescence. A considerable reduction of $T_1$ by up to a factor of $\sim$ 2 has been observed as compared to a quantum dots reference, reflecting the inter-dot coherence. Increase of the molecular coupling strength leads to a systematic decrease of $T_1$ with decreasing barrier width, as for wide barriers a fraction of structures shows reduced coupling while for narrow barriers all molecules appear to be well coupled. The coherent excitons in the molecules gain the oscillator strength of the excitons in the two separate quantum dots halving the exciton lifetime. This superradiance effect contributes to the previously observed increase of the homogeneous exciton linewidth, but is weaker than the reduction of $T_2$. This shows that as compared to the quantum dots reference pure dephasing becomes increasingly important for the molecules.

References in corpus (4)

• Spontaneous Emission Spectrum in Double Quantum Dot Devices
• Direct Observation of Controlled Coupling in an Individual Quantum Dot Molecule
• Dephasing in Quantum Dots: Quadratic Coupling to Acoustic Phonons
• Photoluminescence of a single InAs quantum dot molecule under applied electric field

Cited by in corpus (16)

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• Robust states in semiconductor quantum dot molecules
• Excitonic exchange effects on the radiative decay time of monoexcitons and biexcitons in quantum dots
• Direct observation of acoustic phonon mediated relaxation between coupled exciton states in a single quantum dot molecule
• Quantum interference and control of the optical response in quantum dot molecules
• Collective modes of quantum dot ensembles in microcavities
• Coherent control of indirect excitonic qubits in optically driven quantum dot molecules
• Vacuum-induced coherence in quantum dot systems
• Phonon effects on the radiative recombination of excitons in double quantum dots
• Optically controlled phase gate for two spin qubits in coupled quantum dots
• Effects of interatomic interaction on cooperative relaxation of two-level atoms
• Dephasing of InAs quantum dot p-shell excitons using two-dimensional coherent spectroscopy
• Excitonic entanglement of protected states in quantum dot molecules
• Theory of Polaron Resonance in Quantum Dots and Quantum-Dot Molecules
• Spectral broadening of optical transitions at tunneling resonances in InAs/GaAs coupled quantum dot pairs