Proposal on Detecting Rotational Quantum Vacuum Friction

Quantum friction predicts that two neutral bodies with a relative motion will experience a friction force due to quantum vacuum fluctuations. However, quantum vacuum friction has never been observed experimentally due to its small amplitude. In this chapter, we propose to detect the rotational vacuum friction torque by a levitated nanorotor near a surface. We will first introduce our ultrasensitive torque sensor with an unprecedented torque sensitivity. After that, we will present the calculation of rotational quantum vacuum friction on a rotating silica sphere near a silica surface. Compared to the torque sensitivity, our system will be able to detect the rotational vacuum friction torque. Besides, we also investigate on the rotational vacuum friction torque for a barium strontium titanate (BST) system. The rotational vacuum friction torque can be enhanced by several orders at a rotating frequency around GHz because of the resonant photon tunneling. Parts of the contents in this chapter have been published in Ahn et al. (Nat Nanotechnol 15(2):89–93, 2020) and Xu et al. (Nanophotonics 10(1):537–543, 2021).