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Radiation-suppressed superconducting quantum bit in a planar geometry

2013; American Institute of Physics; Volume: 102; Issue: 7 Linguagem: Inglês

10.1063/1.4792698

1520-8842

Martin Sandberg, Michael Vissers, Thomas Ohki, Jiansong Gao, José Aumentado, Martin Weides, David P. Pappas,

Quantum Computing Algorithms and Architecture

We present a superconducting qubit design that is fabricated in a 2D geometry over a superconducting ground plane to enhance the lifetime. The qubit is coupled to a microstrip resonator for readout. The circuit is fabricated on a silicon substrate using low loss, stoichiometric titanium nitride for capacitor pads and small, shadow-evaporated aluminum/aluminum-oxide junctions. We observe qubit relaxation and coherence times ($T_1$ and $T_2$) of 11.7 $\pm$ 0.2 $μ$s and 8.7 $\pm$ 0.3 $μ$s, respectively. Calculations show that the proximity of the superconducting plane suppresses the otherwise high radiation loss of the qubit. A significant increase in $T_1$ is projected for a reduced qubit-to-superconducting plane separation.