Stefan Ludwig, Fakultät für Physik, Ludwig-Maximilians-Universität, Munich

Jeudi 20 Fevrier 2014, 14h
Amphi Holweck, Esc C, 1ème etage

Electron-Phonon Interaction in Nanostructures :
Detector Backaction, Phonon Interference and Single Phonon Detection

Stefan Ludwig
Fakultät für Physik, Ludwig-Maximilians-Universität

Electron-phonon interaction can strongly influence the dynamics of mesoscopic quantum circuits ; in nanostructures it can be further enhanced by size effects. A prominent example is detector backaction where phonons emitted from a non-equilibrium detector destroy the coherence of solid-state qubits. Taking a more optimistic perspective, it seems thinkable to actually use phonons for information processing in electron-phonon hybrid-systems.

In this talk I will present few experiments performed in the two-dimensional electron system of a GaAs/AlGaAs heterostructure which demonstrate the significance and potential of electron-phonon interaction for future technologies in semiconductor based nanoelectronics. After considering the electron-phonon interaction of a single hot electron in two dimensions [1] we will discuss phonon-mediated backaction from a quantum-point-contact charge detector onto a double quantum dot qubit [2,3]. We will explore quantum interference in phonon absorption in the double quantum dot and discuss its implications for detector backaction [3]. Finally, I will explain the possibility to use double quantum dots as single phonon detectors or emitters, the starting point of phononic information processing ?

Only if time permits I will briefly introduce a recent experiment which probes the electron-phonon interaction in a double quantum dot using Landau-Zener interferometry [4].

references :

[1] Phonon-mediated non-equilibrium interaction between nanoscale devices ;
G.J. Schinner et al. : Phys. Rev. Lett. 102, 186801 (2009).

[2] Phonon-mediated vs. Coulombic Back-Action in Quantum Dot circuits ;
D. Harbusch et al. : Phys. Rev. Lett. 104, 196801 (2010).

[3] Quantum interference and phonon-mediated back-action in lateral quantum-dot circuits ; G. Granger et al. : Nature Phys. 8, 522–527 (2012).

[4] Characterization of Qubit Dephasing by Landau-Zener Interferometry ;
F. Forster et al. : arXiv:1309.5907.

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