Characterization of qubit dephasing by Landau-Zener-Stückelberg-Majorana interferometry.
Controlling coherent interaction at avoided crossings and the dynamics there is at the heart of quantum information processing. A particularly intriguing dynamics is observed in the Landau-Zener regime, where periodic passages through the avoided crossing result in an interference pattern carrying information about qubit properties. In this Letter, we demonstrate a straightforward method, based on steady-state experiments, to obtain all relevant information about a qubit, including complex environmental influences. We use a two-electron charge qubit defined in a lateral double quantum dot as test system and demonstrate a long coherence time of T2 ≃ 200 ns, which is limited by electron-phonon interaction.
Center for NanoScience & Fakultät für Physik, LMU-Munich, 80539 München, Germany.
F
F
Forster
Center for NanoScience & Fakultät für Physik, LMU-Munich, 80539 München, Germany.
G
G
Petersen
Center for NanoScience & Fakultät für Physik, LMU-Munich, 80539 München, Germany.
S
S
Manus
Institut für Physik, Universität Augsburg, 86135 Augsburg, Germany.
P
P
Hänggi
Fakultät für Physik, Universität Regensburg, 93040 Regensburg, Germany.
D
D
Schuh
Fakultät für Physik, Universität Regensburg, 93040 Regensburg, Germany and Solid State Physics Laboratory, ETH Zurich, 8093 Zurich, Switzerland.
W
W
Wegscheider
Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid, Spain.
S
S
Kohler
Center for NanoScience & Fakultät für Physik, LMU-Munich, 80539 München, Germany.
S
S
Ludwig