Dynamic properties of carbon nanotube based hybrid quantum circuits

Schonenberger Christian, Minkyung Jung, V. Ranjan +6 more

Matthias Mergenthaler, Ani Nersisyan, Andrew Patterson +6 more

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 $10$--$200\phantom{\rule{0.2em}{0ex}}\mathrm{ns}$.

Koji Ishibashi, Satoshi Moriyama, Tomoko Fuse +2 more

Landry Bretheau

Edward A. Laird

Hybrid circuit quantum electrodynamics (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 realise the junction by contacting a carbon nanotube with a superconducting Pd/Al bi-layer, 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 -200 ns.

Ben H. Schneider

Carbon nanotubes are unique candidates to study quantum mechanical properties of a nanomechanical resonator. However to access this quantum regime, present detectors are not yet sensitive enough. In this thesis we couple a carbon nanotube CNT mechanical resonator to a superconducting circuit which is a root towards such sensitivity.