Measurement of non-monotonic Casimir forces between silicon nanostructures

• Published in: Nature photonics Vol. 11; no. 2; pp. 97 - 101
• Main Authors: Tang, L., Wang, M., Ng, C. Y., Nikolic, M., Chan, C. T., Rodriguez, A. W., Chan, H. B.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.02.2017; Nature Publishing Group
• Subjects: 142/126; 147/135; 639/624/400; 639/925/927/1021; Actuators; Alignment; Applied and Technical Physics; Design; Displacement; Electrodes; Electromagnetic fields; Fluctuation; Geometry; letter; Nanostructure; Optical properties; Photonics; Physics; Platforms; Quantum Physics; Silicon; Hong Kong China; China
• ISSN: 1749-4885; 1749-4893
• DOI: 10.1038/nphoton.2016.254

Previous demonstrations of the elusive Casimir force between interfaces exhibit monotonic dependence on surface displacement. Now a non-monotonic dependence of the force has been shown experimentally by exploting nanostructured surfaces. Casimir forces are of fundamental interest because they originate from quantum fluctuations of the electromagnetic field 1 . Apart from controlling this force via the optical properties of materials 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , a number of novel geometries have been proposed to generate repulsive and/or non-monotonic Casimir forces between bodies separated by vacuum gaps 12 , 13 , 14 . Experimental realization of these geometries, however, is hindered by the difficulties in alignment when the bodies are brought into close proximity. Here, using an on-chip platform with integrated force sensors and actuators 15 , we circumvent the alignment problem and measure the Casimir force between two surfaces with nanoscale protrusions. We demonstrate that the force depends non-monotonically on the displacement. At some displacements, the Casimir force leads to an effective stiffening of the nanomechanical spring. Our findings pave the way for exploiting the Casimir force in nanomechanical systems using structures of complex and non-conventional shapes.