Coherent control of a semiconductor qubit in the strong coupling regime: Impact of energy and phase relaxation mechanisms

Alexandre Enderlin (1) , Marco Ravaro (1) , Valia Voliotis (1) , Roger Grousson (1) , Xue-Lun Wang

1 INSP - Institut des Nanosciences de Paris

We report on coherent control of the fundamental exciton state in a single quantum dot by means of two phase-locked picosecond laser pulses. By analyzing the experiments performed in the Rabi regime and comparing them to numerical simulations, we show that we can address the exciton coherence and get an insight into the involved dephasing processes. The total decoherence time T(2) (170 ps) is comparable to the effective exciton lifetime T(1) (200 ps), although not reaching the upper theoretical limit of 2T(1). We conclude that energy relaxation and pure dephasing processes due to virtual scattering with phonons both contribute on an equal footing to the loss of coherence in this kind of monolayer-step-induced GaAs quantum dots.

Mots clés: excitons; gallium arsenide; high-speed optical techniques; III-V semiconductors; phonon-exciton interactions; quantum computing; semiconductor quantum dots

Domaines: Matière Condensée [cond-mat]

Alexandre Enderlin, Marco Ravaro, Valia Voliotis, Roger Grousson, Xue-Lun Wang. Coherent control of a semiconductor qubit in the strong coupling regime: Impact of energy and phase relaxation mechanisms. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2009, 80 (8), ⟨10.1103/PhysRevB.80.085301⟩. ⟨hal-01229252⟩