Quantum Optics Colloquium by Adrian Bachtold
Nanotube Electro-Mechanical Resonators
Speaker: Adrian Bachtold, ICFO, The Barcelona Institute of Science and Technology, Spain
Abstract: Mechanical resonators based on carbon nanotubes feature a series of truly exceptional properties. Carbon nanotubes are the lightest resonators fabricated thus far. The mechanical vibrations are enormously sensitive to the electrons flowing through the nanotube, and vice versa. Taking advantage of this coupling, we developed a novel detection method that allows us to measure the mechanical vibrations of nanotube resonators with an unprecedented sensitivity . In this talk, I will discuss our efforts to cool the amplitude of the thermal vibrations to a few quanta . Cooling is achieved using a simple yet powerful method, which consists in applying a constant (DC) current of electrons through the suspended nanotube in a dilution fridge. I will also present results where we strongly couple mechanical vibrations to the two electron states involved in single-electron tunnelling (SET). It effectively creates a highly nonlinear potential for mechanical vibrations despite the relatively low quanta population (about 80 quanta). This enables us to demonstrate the polaronic nature of charge transport through a nanoelectromechanical device.
 S. L. de Bonis, C. Urgell, W. Yang, C. Samanta, A. Noury, J. Vergara-Cruz, Q. Dong, Y. Jin, A. Bachtold, Ultrasensitive Displacement Noise Measurement of Carbon Nanotube Mechanical Resonators, Nano Letters 18, 5324 (2018)
 C. Urgell, W. Yang, S. L. de Bonis, C. Samanta, M. J. Esplandiu, Q. Dong, Y. Jin, A. Bachtold, Cooling and Self-Oscillation in a Nanotube Electro-Mechanical Resonator, Nature Physics (2019)