Zero-phonon line shape in single InAs/GaAs quantum dots
Résumé
In this paper, I will discuss the extrinsic dephasing mechanism of spectral diffusion that dominates the decoherence in semiconductor quantum dots at cryogenic temperature. I will first present the existence of two fluctuation regimes: the slow modulation one where the zero-phonon line in the quantum dot optical spectrum directly reflects the statistical distribution of the quantum dot emission energy, and the fast modulation one, also called motional narrowing regime, where the zero-phonon line is a Lorentzian with a width smaller than the standard deviation of the quantum dot energy. I will then emphasize the unconventional phenomenology of motional narrowing in standard semiconductor quantum dots at low incident power and temperature, that makes the quantum dot emission line a sensitive probe of the extrinsic reservoir fluctuation dynamics [1,2]. I will further show that the text book phenomenology of motional narrowing in nuclear magnetic resonance is recovered in quantum dots embedded in field-effect heterostructure. In that case, the electrical control of the mesoscopic environment of the quantum dot leads to conventional motional narrowing where the motion consists in carrier tunneling out of the defects around the quantum dot [3]. References [1] A. Berthelot, I. Favero, G. Cassabois, C. Voisin, C. Delalande, Ph. Roussignol, R. Ferreira, and J. M. Gérard, Nature Phys. 2, 759 (2006). [2] I. Favero, A. Berthelot, G. Cassabois, C. Voisin, C. Delalande, Ph. Roussignol, R. Ferreira, and J. M. Gérard, Phys. Rev. B 75, 073308 (2007). [3] A. Berthelot, G. Cassabois, C. Voisin, C. Delalande, R. Ferreira, Ph. Roussignol, J. Skiba-Szymanska, R. Kolodka, A. I. Tartakovskii, M. Hopkinson, and M. S. Skolnick, NewJ. Phys. 11, 093032 (2009).