Circuit Quantum Electrodynamics with Carbon-Nanotube-Based Superconducting Quantum Circuits

Mergenthaler, M. and Nersisyan, A. and Patterson, A. and Esposito, M. and Baumgartner, A. and Schönenberger, C. and Briggs, G.A.D. and Laird, E.A. and Leek, P.J. (2021) Circuit Quantum Electrodynamics with Carbon-Nanotube-Based Superconducting Quantum Circuits. Physical Review Applied, 15 (6): 064050. ISSN 2331-7019

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Abstract

Hybrid circuit QED involves the study of coherent quantum physics in solid-state systems via their interactions with superconducting microwave circuits. Here we present a crucial step in the implementation of a hybrid superconducting qubit that employs a carbon nanotube as a Josephson junction. We realize the junction by contacting a carbon nanotube with a superconducting Pd/Al bilayer, and implement voltage tunability of the quantum circuit's frequency using a local electrostatic gate. We demonstrate a strong dispersive coupling to a coplanar waveguide resonator by investigating the gate-tunable resonator frequency. We extract qubit parameters from spectroscopy using dispersive readout and find qubit relaxation and coherence times in the range of 10-200ns.