Regensburg 2013 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
HL: Fachverband Halbleiterphysik
HL 11: Quantum information systems: mostly quantum dots
HL 11.5: Vortrag
Montag, 11. März 2013, 13:00–13:15, H16
A Landau-Zener-Stückelberg charge qubit — •Florian Forster1, Gunnar Petersen1, Dieter Schuh2, Werner Wegscheider3, Sigmund Kohler4, and Stefan Ludwig1 — 1CeNS, Universität München — 2Universität Regensburg — 3ETH Zürich — 4Inst. Ciencia Materiales, CSIC, Madrid
Quantum dots in the few electron regime in GaAs/AlGaAs heterostructures are a powerful system for observing fundamental quantum effects. For instance, it is possible to prepare arbitrary charge superposition states of a double quantum dot (DQD) by driving it through avoided crossings. Multiple Landau-Zener transitions can give rise to quantum interference in time, in analogy to the interference in space in Mach-Zehnder interferometers. Here, we perform Landau-Zener-Stückelberg (LZS) interferometry [1] by periodically driving a DQD between two-electron singlet states. We analyze the decoherence of this strongly driven charge qubit as a function of temperature and external noise. Our goal is to use LZS interferometry as a tool to probe the solid state environment interacting with the qubit. To reach this goal we compare our experimental data with numerical calculations based on the Floquet transport theory [2] augmented by dissipative terms. This approach allows an accurate determination of qubit coherence times and its bath properties. Our fundamental studies lay the basis for possible applications in quantum information based on qubits at the interface between adiabatic and non-adiabatic quantum dynamics.
[1] S. N. Shevchenko et. al., Phys. Rep. 492, 1-30 (2010)
[2] S. Kohler et al., Phys. Rep. 406, 397 (2005)