Adrian Bachtold

What is the difference between a mechanical resonator made from a nanotube and a guitar string?  

ICFO – The Institute of Photonic Sciences, Spain

When a carbon nanotube is suspended and clamped at the ends, the nanotube vibrates in way similar to a guitar string. However, one difference is the mass, since the diameter of nanotubes is about 1 nm. Another difference is that the quality factor Q becomes extremely large at cryogenic temperature, up to 5 million. This large Q-factor reflects the high crystallinity of nanotubes and their lack of dangling bonds at the surface. Because of this combination of low mass and high quality factor, the motion is enormously sensitive to the environment - the mechanical eigenstates of the nanotube are extremely fragile and easily perturbed by the measurement. But, if nanotube resonators can be properly harnessed, they become incomparable sensors of mass and force. From a fundamental point of view, nanotube resonators are very interesting to study the physics of noise.