Optically induced spin rotations in quantum dots

Sophia E. Economou, T. L. Reinecke

Sophia E. Economou, T. L. Reinecke

A method is proposed for the optical rotation of the spin of an electron in a quantum dot using excited trion states to implement operations significantly faster than those of most existing proposals. Key ingredients are the geometric phase induced by 2pi hyperbolic secant pulses, use of coherently trapped states and use of naturally dark states. Our proposal covers a variety of quantum dots by addressing different parameter regimes. Numerical simulations with typical parameters for InAs self-assembled quantum dots, including their dissipative dynamics, give fidelities of the operations in excess of 99%.

Jan Gui‐Hyon Dreiser, Mete Atatüre, A. Badolato +1 more

Here, we present an all-optical dispersive measurement of a single spin confined in a self-assembled InAs/GaAs quantum dot (QD) (Atature etl., 2007). The time-averaged spin-state is observed via spin-dependent Faraday rotation of a spectrally detuned laser, induced by the polarization-and spin-selective trion transitions. The measurement was performed with a spin prepared by an independent laser (Atature et al., 2006) and in the case of a thermal state.

J. M. Villas-Bôas, Sergio E. Ulloa, Alexander O. Govorov

Timothy M. Godden, John H. Quilter, A. J. Ramsay +7 more

We demonstrate coherent optical control of a single hole spin confined to an InAs/GaAs quantum dot. A superposition of hole-spin states is created by fast (10-100 ps) dissociation of a spin-polarized electron-hole pair. Full control of the hole spin is achieved by combining coherent rotations about two axes: Larmor precession of the hole spin about an external Voigt geometry magnetic field, and rotation about the optical axis due to the geometric phase shift induced by a picosecond laser pulse resonant with the hole-trion transition.

Gabriela M. Slavcheva, Ortwin G. Hess