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Phonon-Assisted Population Inversion of a Single InGaAs / GaAs Quantum Dot by Pulsed Laser Excitation

2015; American Physical Society; Volume: 114; Issue: 13 Linguagem: Inglês

10.1103/physrevlett.114.137401

1092-0145

J. H. Quilter, Alistair J. Brash, Feng Liu, M. Glässl, A. M. Barth, V. M. Axt, A. J. Ramsay, M. S. Skolnick, A. M. Fox,

Spectroscopy and Quantum Chemical Studies

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.