Berlin 2012 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 8: Transport: Quantum Coherence and Quantum Information Systems 1 (jointly with TT, MA)
HL 8.3: Talk
Monday, March 26, 2012, 10:00–10:15, BH 243
Gradiometric persistent current flux qubit with tunable tunnel coupling — •Manuel Johannes Schwarz1,2, Jan Goetz1,2, Zhaohai Jiang1,2, Frank Deppe1,2, Achim Marx1, and Rudolf Gross1,2 — 1Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Garching — 2Physik Department, TU München, Garching
The persistent current flux qubit is a Josephson junction based superconducting circuit exhibiting strong anharmonicity and excellent coherence time of more than 10 µ s. However, quantum coherence deteriorates drastically away from an optimal operation point. Moreover, a controlled adjustment of the transition frequency at the optimal point requires excellent stability of the fabrication process. Here, we present the spectroscopic analysis of a gradiometric flux qubit, where the minimal transition frequency, the qubit gap, can be tuned in situ while staying at the point of optimal coherence. We show a tunability of the qubit gap from a few hundreds of megahertz to several gigahertz, making the system suitable for future experiments with coupled qubit-resonator systems.
This work is supported by the DFG via SFB 631 and by the German Excellence Initiative via NIM.