CPM Seminar

Carbon nanotube resonators coupled to charge and flux

Gary Steele

Delft University of Technology

We study the motion of carbon nanotube resonators coupled to single electron charges, and to magnetic flux. Using a single electron transistor embedded in the nanotube to read out the motion of the high quality factor resonator (Q ~ 150,000), we observe the static force exerted on the nanotube by a single electron, and frequency dips from a ‘single-electron spring’. Using a suspended carbon nanotube SQUID, we couple magnetic flux to the nanotube motion. We find a record-high critical current of 24 nA and supercurrents that persist to magnetic fields greater than 3 T. The magnetic flux in the SQUID is tuned by a DC gate voltage, allowing us to couple to displacements of the nanotube with a strength of 0.4 mΦ₀/pm. Incorporating these new nanomechanical SQUIDs into superconducting resonator and qubit circuits will enable the readout and control of nanotube mechanical motion a the single phonon level.