Chan group

Casimir forces in micromechanical systems



In 1948, H. B. G. Casimir predicted that two electrically neutral conducting plates attract each other. Such attraction is quantum mechanical in nature and arises due to the confinement of the quantum zero point fluctuations of the electromagnetic field. This interaction between surfaces, known as the Casimir force, increases rapidly with decrease in their separation. A number of experiments in the late 1990's produced convincing confirmation of Casimir's prediction, achieving agreement of a few percent. In 2001, Prof. Chan and his collaborators at Bell Labs demonstrated that the motion of a micromechanical torsional can be created solely based on this quantum electrodynamical effect. Furthermore, the Casimir force was found to have a profound influence on the oscillatory behavior of the device, leading to bistability and hysteresis in the frequency response. These experiments established the importance of quantum electrodynamical effects in micro- and nano-mechanical devices. It has also been pointed out that the Casimir force could also have a negative impact on the fabrication and operation of micro- and nano-mechanical devices. For instance, the Casimir force can in part be responsible for initiating two surfaces to move into contact and result in undesirable stiction.

Since the Casimir force arises from the boundary conditions on the quantum fluctuations, it opens the possibility of tailoring and manipulating it through the optical properties and/or the shape of the interacting objects. The focus of our group is to investigate the geometry dependence of the Casimir force. We are particularly interested in geometries where the Casimir force cannot be obtained from the pairwise addition of van der Waals forces. In 2008, we demonstrated the non-trivial boundary dependence of the Casimir force on a silicon surface with a array of deep trenches. Deviations up to 20% from the pairwise additive approximation and proximity force approximation was observed. We continue to explore the Casimir force in a number of unconventional geometries.


Strong geometry dependence of the Casimir force between interpenetrated rectangular gratings

M. Wang, L. Tang, C. Y. Ng, R. Messina, B. Guizal, J. A. Crosse, M. Antezza, C. T. Chan and H. B. Chan

Nature Communications 12, 600 (2021). pdf


Giant Casimir Torque between Rotated Gratings and the θ=0 Anomaly

M. Antezza, H. B. Chan, B. Guizal, V. N. Marachevsky, R. Messina and M. Wang

Physical Review Letters 124, 013903 (2020). pdf


Measurement of non-monotonic Casimir forces between silicon nanostructures

L. Tang, M. Wang, C. Y. Ng, M. Nikolic, C. T. Chan, A. W. Rodriguez and H. B. Chan

Nature Photonics 11, 97 (2017). pdf


Casimir forces on a silicon micromechanical chip

J. Zou, Z. Marcet, A. W. Rodriguez, M. T. H. Reid, A. P. McCauley, I. I. Kravchenko, T. Lu, Y. Bao, S. G. Johnson and H. B. Chan

Nature Communications 4, 1845 (2013). pdf


Thermal Casimir force between nanostructured surfaces

R. Guérout, J. Lussange, H. B. Chan, A. Lambrecht and Serge Reynaud

Physical Review A  87, 052514 (2013). pdf


Casimir force on a surface with shallow nanoscale corrugations: geometry and finite conductivity effects

Y. Bao, R. Guérout, J. Lussange, A. Lambrecht, R. A. Cirelli, F. Klemens, W. M. Mansfield, C. S. Pai and H. B. Chan,

Physical Review Letters  105, 250402 (2010). pdf


Demonstrating the strong geometry dependence of the Casimir force on a surface with deep, nanoscale corrugations

H. B. Chan, Y. Bao, J. Zou, R. A. Cirelli, F. Klemens, W. M. Mansfield, J. Miner and C. S. Pai

International Journal of Modern Physics A 25, 2212 (2010). pdf



Shaping the void

A. Lambrecht

Nature 454, 836 (2008). pdf



How Casimir forces are shaping up

S. K. Lamoreaux

Physics  1, 4 (2008). link



The Casimir effect: Much ado nothing

Economist  May 22 (2008). link


Measurement of the Casimir force between a gold sphere and a silicon surface with nanoscale trench arrays

H. B. Chan, Y. Bao, J. Zou, R. A. Cirelli, F. Klemens, W. M. Mansfield, J. Miner and C. S. Pai

Physical Review Letters  101, 030401 (2008). pdf


Casimir forces and quantum electrodynamical torques: physics and nanomechanics

F. Capasso, J. N. Munday, D. Iannuzzi and H. B. Chan

IEEE Journal of Selected Topics in Quantum Electronics 13, 400 (2007). pdf


Constraining new forces in the Casimir regime using the isoelectronic technique

R. S. Decca, D. Lopez, H. B. Chan, E. Fischbach, D. E. Krause and C. R. Jamell

Physical Review Letters 94, 240401 (2005). pdf


Precise determination of the Casimir force and first realization of a Casimir-less experiment

R. S. Decca, D. Lopez, H. B. Chan, E. Fischbach, G. L. Klimchitskaya, D. E. Krause and V. M. Mostepanenko

Journal of Low Temperature Physics 135, 64 (2004).



Nonlinear Micromechanical Casimir Oscillator

H. B. Chan, V. A. Aksyuk, R. N. Kleiman, D. J. Bishop and F. Capasso

Physical Review Letters 87, 211801 (2001). pdf


Quantum Mechanical Actuation of Microelectromechanical Systems by the Casimir Force

H. B. Chan, V. A. Aksyuk, R. N. Kleiman, D. J. Bishop and F. Capasso

Science 291, 1941 (2001). pdf