The Casimir Force

Vacuum, Light, & Quantum Physics

Starlight passing through vacuum of space consists of electromagnetic waves.

Like position & momentum, electric and magnetic fields are subject to (Heisenberg) quantum uncertainty

The quantum vacuum is thus a cauldron of fluctuating electric and magnetic fields.

 H.B.G. Casimir examined consequences of confining these fluctuations between plates, in

"On the attraction between two perfectly conducting plates," Proc. K. Ned. Akad. Wet. 51, 793 (1948)

Quantum fluctuations of electromagnetic field in the vacuum lead to an attractive force, scaling with separation H as

Myriad of Fluctuation-Induced Forces

   

High Precision experimental verification

made possible by advent of scanning force microscopy in the 1990s, by several groups, including:

 "Demonstration of the Casimir Force in the 0.6 to 6µm Range," (using a torsion pendulum)

S.K. Lamoreaux, Phys. Rev. Lett. 78, 5 (1997)

   

  "Precision Measurements of the Casimir Force from 0.1 to 0.9µm," (using atomic force microscopy)

U. Mohideen and A. Roy, Phys. Rev. Lett. 81, 4549 (1998) (offline)

Technology applications

Important in microelectromechanical systems (MEMS): micron-scale metallic machines

  "Quantum Mechanical Actuation of Microelectromechanical Systems by the Casimir Force,"

 H. B. Chan, V. A. Aksyuk, R. N. Kleiman, D. J. Bishop, Federico Capasso, Science 291, 1941 (2001)

   

  Stiction due to the attractive Casimir force is a challenge to design and operation of MEMs

  "The role of the casimir effect in the static deflection and stiction of membrane strips in MEMS,"

 F. Michael Serry, Dirk Walliser, and G. Jordan Maclay, J. Appl. Phys. 84, 2501 (1998)

  "Stiction, adhesion energy, and the Casimir effect in micromechanical systems,"

 E. Buks and M. L. Roukes, Phys. Rev. B 63, 033402 (2001)

Next (Repulsion?) Outline Casimir force Repulsion? Scattering approach Earnshaw's theorem Out of equilibrium Dynamic phenomena Summary