The Casimir Force

Vacuum, Light, & Quantum Physics

blue triangleStarlight passing through vacuum of space consists of electromagnetic waves.

vacuum + stars

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

EM wave     Heisenberg Uncertainty

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

vaccuum fluctuations

red ball Hendrik Casimir examined consequences of confining these fluctuations between plates, in

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

Casimir Blobs

yellow ball Quantum fluctuations of electromagnetic field in the vacuum lead to an attractive force, depending only on fundamental constants,

, scaling with separation  H  as

yellow ball Myriad of Fluctuation-Induced Forces

   Water wave

High Precision experimental verification

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

yellow ball "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)

   

yellow ball  "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)

yellow ball   Many other groups since ....

Technology applications

red ball Relevant to microelectromechanical systems (MEMS): micron-scale metallic machines

MEMmite         failOring

yellow ball  "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)

   

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

  yellow ball"The role of the Casimir effect in the static deflection and stiction of membrane strips in MEMS,"Ferry,Walliser,Maclay,J.Appl.Phys.84,2501(98)

  yellow ball"Stiction, adhesion energy, and the Casimir effect in micromechanical systems," E. Buks and M. L. Roukes, Phys. Rev. B 63, 033402 (2001)

KITP program in 2008

red ballThe Theory and Practice of Fluctuation-Induced Interactions

  yellow ballDARPA program on Casimir Effect Enhancement (offline)

yellow ball Description of the program in Scientific American (2009)