Electrostatic calibration method for large-amplitude dynamic Casimir force measurements

Abstract

Electrostatic calibration is important in Casimir force measurements. It is necessary for the estimation of the unknown system parameters such as the absolute separation distance and the identification of the electrostatic force model. Correct estimates of the unknown parameters and the electrostatic force model are crucial for interpreting the Casimir force data. In this paper, we present an electrostatic calibration method with higher sensitivity and robustness. It is based on large-amplitude dynamic force measurements. It is proven in theory that the unknown system parameters can be obtained accurately and the electrostatic force model can be identified by our method. The effectiveness and robustness of our method are tested on synthetic data with added noise when the Casimir force measurement is conducted between a sphere and a flat surface.

Combined atomic force microscopy and voltage pulse technique to accurately measure electrostatic force

“…43) 4.4 V p -dependent dissipation curves Measuring V Ã cpd ðzÞ is important not only to obtain F ele but also to check the homogeneity of the tip-sample system. For example, Casimir force measurement is usually carried out by measuring the force between a large sphere and a metal plate, 4,[32][33][34] where the interaction areas of the two objects are large compared with those of the tip-sample system such as in our experiment. Under this condition, electrostatic contributions by the body part of the tip in our experiment are strongly enhanced, and thus, the existence of fractional patch potentials becomes a serious problem in the precise extraction of the Casimir force.…”

“…Under this condition, electrostatic contributions by the body part of the tip in our experiment are strongly enhanced, and thus, the existence of fractional patch potentials becomes a serious problem in the precise extraction of the Casimir force. 33,34) Therefore, the measurement requires the preparation of a clean surface and sphere and clarification of whether there are undesirable patch potentials. A clear V Ã cpd ðzÞ difference depending on the tip conditions [Figs.…”

“…8,11,12,14,15) Another important challenge for AFM is to extract particular long-range forces from the measured forces. 1) For instance, accurate extraction of electrostatic force (F ele ), which is dominant among the long-range forces in most cases, is crucial in separating the origins of force=currentinduced atom manipulations, [16][17][18] measuring the contact potential difference by Kelvin probe force microscopy (KPFM), [19][20][21][22][23][24][25][26][27][28] and extracting other tiny forces such as Casimir forces, [29][30][31][32][33][34][35][36] noncontact friction, [37][38][39] and non-Newtonian gravitational forces. 40) Since these studies need F ele to be detected with high sensitivity and stability, FM-AFM is usually used in the measurements.…”