Control of photon, carrier, and spin by dynamic acoustic fields

Orateur : Paulo VENTURA SANTOS (Paul-Drude Institut, Berlin, Germany)

Coherent acoustic phonons in the form of surface acoustic waves (SAWs) propagating on a surface induces a moving elastic and piezoelectric modulation of the underlying material. In semiconductor nanostructures, this dynamic modulation can create moving potential dots, which laterally confine carriers and transport them along the surface with the acoustic velocity. The first part of the talk addresses applications of the acoustic transport for single-photon generation. We show that single-photon sources operating at GHz rates can be realized by using SAW to transfer carriers between quantum wires and dots structures fabricated on a GaAs wafer. In the second part of the talk, I review recent results on the acoustic transport of spin polarized carriers in GaAs quantum well (QW) structures. The spatial confinement of the carriers within moving acoustic dots reduces spin dephasing during transport, thereby enhancing the spin lifetime and enabling transport over long distances. The spin transport lengths can be further enhanced in QWs grown along non-conventional crystallographic orientations (such as along the [110] crystallographic axis). As a result of the reduced spin-orbit interaction in these QWs, spins can be transport over tens of µm at temperatures above 100 K. Perspectives for spin transport in GaAs QWs at room temperatures will be discussed.

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