We study a Josephson junction with an embedded high-frequency and high-quality mechanical resonator, made from a suspended carbon nanotube. Good transparency of the superconductor–nanotube interface allows for the observation of supercurrent through the suspended nanotube, owing to the Josephson effect. The magnitude of the supercurrent is dependent on the charge on the nanotube and can be periodically modulated by a gate electrode, similar to previously reported experiments in unsuspended carbon nanotube Josephson junctions.
In such a device we find a 1GHz mechanical resonance frequency and a Q factor of 500000. In the regime where the AC Josephson current and charge oscillations induced by the nanotube motion are resonant, we observe a signal of the mechanical resonator that can be contributed to the interplay of Josephson dynamics and mechanical dynamics. Our work is motivated by the search for a new and sensitive vibration detector, ultimately to measure the ground state motion of the nanotube resonator.

C.J.H. Keijzers, C. Padurariu, S.M. Frolov, G.A. Steele, Y.V. Nazarov, L.P. Kouwenhoven