Fig. 1: Fabrication of nanotube gatemon qubits.
a Schematic of the hybrid cQED architecture containing a carbon nanotube Josephson junction. The nanotube is transferred onto two Nb–Au electrodes (gold) to form a Josephson junction of energy EJ that can be tuned with gate voltage Vg. Together with the shunt capacitor of energy EC it implements a gatemon qubit (orange box), which is capacitively coupled to the readout resonator (light blue). b False-colored micrograph of the nanotube gatemon. The central charge island (purple), which implements the shunt capacitor, is coupled to a λ/2 resonator and connected to the ground plane through the carbon nanotube Josephson junction. The carbon nanotube (not visible) is covered by hBN (green) and a top gate (dark blue). c Layout of the full chip with two independent hybrid cQED architectures. Device A corresponds to the bottom one, its resonator being highlighted in blue. Bonding pad on the bottom of the chip is used for top gate control.
