Letter | Published:

Measurement of non-monotonic Casimir forces between silicon nanostructures

Nature Photonics volume 11, pages 97101 (2017) | Download Citation

Abstract

Casimir forces are of fundamental interest because they originate from quantum fluctuations of the electromagnetic field1. Apart from controlling this force via the optical properties of materials2,3,4,5,6,7,8,9,10,11, a number of novel geometries have been proposed to generate repulsive and/or non-monotonic Casimir forces between bodies separated by vacuum gaps12,13,14. 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 actuators15, 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.

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Acknowledgements

H.B.C., L.T. and M.W. are supported by HKUST 16300414 from the Research Grants Council of Hong Kong SAR. C.Y.N. and C.T.C. are supported by AoE/P-02/12 from the Research Grants Council of Hong Kong SAR. M.N. and A.W.R. are supported by the National Science Foundation (grant no. DMR-1454836).

Author information

Affiliations

  1. Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China

    • L. Tang
    • , M. Wang
    • , C. Y. Ng
    • , C. T. Chan
    •  & H. B. Chan
  2. Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA

    • M. Nikolic
    •  & A. W. Rodriguez

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Contributions

L.T. and M.W. fabricated the devices and conducted the measurements. C.Y.N., M.N., A.W.R. and C.T.C. performed the theoretical calculations. H.B.C. conceived and supervised the experiment. All authors discussed the results and contributed to the writing.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to H. B. Chan.

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DOI

https://doi.org/10.1038/nphoton.2016.254

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