Zonghuiyi Jiang, Fangyuan Chen, Zepu Kou, Jun Yin, Xiaofei Liu, Wanlin Guo

The Journal of Physical Chemistry B  , 128, 1, 350–357,  2024.

Abstract: Casimir torque between parallel plates, a macroscopic quantum electrodynamics effect, is known to be induced by dielectric anisotropy and related to the rotational degree of freedom. We here reveal a different type of Casimir torque generated on a Au plate suspended in a quantum trap without recourse to materials anisotropy. As the Au plate deflects from the equilibrium plane with a nonzero flipping angle, the regions departing from and approaching the Teflon-coated Au substrate are subjected to attractive and repulsive Casimir forces, respectively, resulting in a restoring torque about the axis of flipping. For a quantum trap with an equilibrium separation of ∼10 nm, the stiffness per unit area of the Casimir flipping torque can be an order of magnitude larger than those of previously reported dielectric anisotropy-induced rotational torques at the same separation. The large Casimir flipping torque provides the possibility of designing a mechanical oscillator completely dominated by quantum and thermal fluctuations.

Keywords: Coating materials; Equilibrium; Gold; Insulators; Stiffness

Link: https://pubs.acs.org/doi/abs/10.1021/acs.jpcb.3c06922