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Voltage Control of the Spin Dynamics of an Exciton in a Semiconductor Quantum Dot

2005; American Physical Society; Volume: 94; Issue: 19 Linguagem: Inglês

10.1103/physrevlett.94.197402

1092-0145

Jason M. Smith, Paul A. Dalgarno, Richard J. Warburton, Alexander O. Govorov, K. Karraï, Brian D. Gerardot, P. M. Petroff,

Advancements in Semiconductor Devices and Circuit Design

We report the observation of a spin-flip process in a quantum dot whereby a dark exciton with total angular momentum $L=2$ becomes a bright exciton with $L=1$. The spin-flip process is revealed in the decay dynamics following nongeminate excitation. We are able to control the spin-flip rate by more than an order of magnitude simply with a dc voltage. The spin-flip mechanism involves a spin exchange with the Fermi sea in the back contact of our device and corresponds to the high temperature Kondo regime. We use the Anderson Hamiltonian to calculate a spin-flip rate, and we find excellent agreement with the experimental results.