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Conference on Lasers and Electro-Optics

Experimental Evidence of Single-Phonon Mediated Inter-Level Excitonic Transitions in a Semiconductor Quantum Dot

Edward B. Flagg, John W. Robertson, Sebastien Founta, Wenquan Ma, Min Shao, Gregory J. Salamo, Chih-Kang Ken Shih

Published Jan 1, 2009• 1 citation
Publisher

Abstract

Resonance fluorescence of a single InGaAs/GaAs quantum dot enables us to show direct evidence of population up-conversion to an excited state in a quantum dot, which we attribute to single-acoustic-phonon processes at low temperature.
DOI
10.1364/iqec.2009.ithe6

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We demonstrate a new method to realize the population inversion of a single InGaAs/GaAs quantum dot excited by a laser pulse tuned within the neutral exciton phonon sideband. In contrast to the conventional method of inverting a two-level system by performing coherent Rabi oscillation, the inversion is achieved by rapid thermalization of the optically dressed states via incoherent phonon-assisted relaxation. A maximum exciton population of 0.67±0.06 is measured for a laser tuned 0.83 meV to higher energy. Furthermore, the phonon sideband is mapped using a two-color pump-probe technique, with its spectral form and magnitude in very good agreement with the result of path-integral calculations.
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We demonstrate a new method to realize the population inversion of a single InGaAs=GaAs quantum dot excited by a laser pulse tuned within the neutral exciton phonon sideband.In contrast to the conventional method of inverting a two-level system by performing coherent Rabi oscillation, the inversion is achieved by rapid thermalization of the optically dressed states via incoherent phonon-assisted relaxation.A maximum exciton population of 0.67 Æ 0.06 is measured for a laser tuned 0.83 meV to higher energy.Furthermore, the phonon sideband is mapped using a two-color pump-probe technique, with its spectral form and magnitude in very good agreement with the result of path-integral calculations.
We demonstrate an approach to realize the population inversion of a single InGaAs/GaAs quantum dot, which is driven by a laser pulse tuned within the neutral exciton phonon sideband. The inversion is achieved by rapid thermalization of the optically dressed states via phonon-assisted relaxation. A maximum exciton population of 0.67 ±\pm± 0.06 is measured for a laser tuned 0.83 meV to higher energy and the phonon sideband is mapped using a two-color pump-probe technique. Our experiments reveal that, in accordance with theory, the phonon-bath provides additional functionality for an optically driven quantum dot qubit.