5 research outputs found
Optically Levitated Nanodumbbell Torsion Balance and GHz Nanomechanical Rotor
Levitated optomechanics has great potentials in precision measurements,
thermodynamics, macroscopic quantum mechanics and quantum sensing. Here we
synthesize and optically levitate silica nanodumbbells in high vacuum. With a
linearly polarized laser, we observe the torsional vibration of an optically
levitated nanodumbbell in vacuum. The linearly-polarized optical tweezer
provides a restoring torque to confine the orientation of the nanodumbbell, in
analog to the torsion wire which provides restoring torque for suspended lead
spheres in the Cavendish torsion balance. Our calculation shows its torque
detection sensitivity can exceed that of the current state-of-the-art torsion
balance by several orders. The levitated nanodumbbell torsion balance provides
rare opportunities to observe the Casimir torque and probe the quantum nature
of gravity as proposed recently. With a circularly-polarized laser, we drive a
170-nm-diameter nanodumbbell to rotate beyond 1~GHz, which is the fastest
nanomechanical rotor realized to date. Our calculations show that smaller
silica nanodumbbells can sustain rotation frequency beyond 10 GHz. Such
ultrafast rotation may be used to study material properties and probe vacuum
friction