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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: Vortrag

Montag, 7. März 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. Ustinov^1,3, Martin Weides^1,4, 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.