laboratoire pierre aigrain
électronique et photonique quantiques
laboratoire pierre aigrain

Séminaire 31 mai 2010

Preden ROULLEAU<br class='autobr' />Solid State Physics Laboratory, ETH Zurich, 8093 Zurich, Switzerland
Phonons in an InAs nanowire double quantum dot

We have investigated the coupling between phonon modes and electronic states in an InAs nanowire double quantum dot (DQD) which is crucial for the understanding of decoherence mechanisms in InAs nanowires. InAs DQDs are a promising system to realize spin manipulation experiments. The large electronic g* - factor could allow to manipulate the spin with an external magnetic field, whereas strong spin-orbit interactions would enable to realize a purely electrical control of the spin state. However, spin manipulation require to understand decoherence mechanisms and phonon-electron coupling is one of them.
Fig.1(a) shows a scanning electron micrograph image of the measured sample. The nanowire is first deposited on a two-dimensional electron gas (2DEG) ; in a second step trenches in the 2DEG forming the QPCs and the constrictions in the NW forming the DQD are defined in a single step wet etching process [1]. Finally top gates are deposited in the trenches, which enable us to tune the tunnel barriers of the DQD. This technology combines the advantage of a self-aligned charge detector in the 2DEG just below the dots and additional tunability with top gates.
We study the interplay between confined phonons and electrons measuring the electronic transport through the DQD. Both dots are tuned in order to be in the resonant tunneling regime between the two dots and additional transport resonances , due to the phonon environment, are observed (see in Fig.1(b)) [2].
We will show that magnetic field and temperature measurements of the electronic transport through the DQD enable us to discuss the nature of this electron-phonon coupling.

[1] I. Shorubalko et al., Nano Lett. 8, 382 (2008)
[2] C. Weber et al., Phys. Rev. Lett. 104, 036801 (2010)