Abstract

An exciton in a quantum dot (QD) strongly couples to light, allowing the ultrafast manipulation of the quantum states on the order of femtoseconds [1]. Since a QD exciton can be regarded as a two-level system, the excitonic state can be manipulated coherently via Rabi oscillations depending on the electric field of the excitation pulse and the resonant frequency of the QD exciton. However, uniformly manipulating the exciton ensemble in a large number of QDs using ultrashort pulses is quite difficult due to the inhomogeneous distributions of the excitonic resonant frequency and the laser intensity for each QD. Adiabatic rapid passage (ARP) has been demonstrated to overcome this problem because it provides a quantum manipulation technique robust over the inhomogeneities [2, 3] by using chirped pulses (CP) instead of using Fourier transform-limited pulses (TLP). While ARP has been studied extensively in two-level systems with inhomogeneous linewidths up to GHz, it has not been rarely applied to two-level systems with THz inhomogeneous linewidths such as QDs. In this work, we experimentally demonstrate the ultrafast coherent transfer of the exciton population via ARP in two kinds of QD samples; 150-layer stacked InAs QDs and 50-layer stacked InAs QDs embedded in a resonator (Fig. 1 (a)).

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