Regensburg 2016 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 5: Transport: Quantum Coherence and Quantum Information Systems - Experiment
(Joint session of HL, MA and TT organized by TT)
TT 5.2: Talk
Monday, March 7, 2016, 10:00–10:15, H22
Concentric transmon qubit featuring fast tunability and an anisotropic magnetic dipole moment — •Jochen Braumüller1, Martin Sandberg2, Michael R. Vissers2, Andre Schneider1, Steffen Schlör1, Lukas Grünhaupt1, Hannes Rotzinger1, Michael Marthaler1, Alexander Lukashenko1, Amadeus Dieter1, Alexey V. Ustinov1,3, Martin Weides1,4, and David P. Pappas2 — 1Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany — 2National Institute of Standards and Technology, Boulder, Colorado 80305, USA — 3National University of Science and Technology MISIS, Moscow 119049, Russia — 4Johannes Gutenberg University, Mainz, 55128 Mainz, Germany
We present a planar qubit design based on a superconducting circuit that we call concentric transmon. While employing a straightforward fabrication process using Al evaporation and lift-off lithography, we observe qubit lifetimes and coherence times in the order of 10 µ s. We systematically characterize loss channels such as incoherent dielectric loss, Purcell decay and radiative losses. The implementation of a gradiometric SQUID loop allows for a fast tuning of the qubit transition frequency and therefore for full tomographic control of the quantum circuit. Due to the large loop size, the presented qubit architecture features a strongly increased magnetic dipole moment as compared to conventional transmon designs. This renders the concentric transmon a promising candidate to establish a site-selective passive direct Ẑ coupling between neighboring qubits, being a pending quest in the field of quantum simulation.