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The Casimir effect Physics 250 Spring 2006 Dr Budker Eric Corsini. Casimir Patron Saint of Poland and Lithuania (March 4 th ). Hendrik Casimir (1909-2000) Dutch theoretical physicist Predicted the “force from nowhere” in 1948. Abstract The Casimir Force.
Patron Saint of Poland and Lithuania (March 4th)
Hendrik Casimir (1909-2000)
Dutch theoretical physicist
Predicted the “force from nowhere” in 1948
that would violate
Heisenberg uncertainty principle.
(no local current/charge)
- Used the attraction between a pair of parallel plates.
- But irreducible systematic errors measurements had a 100% uncertainty, (but it fit the expectations)
- The plates should be free of any dust or debris, with as little surface roughness as possible
- Static electrical charges should be removed (electrostatic force can easily swamp the weak Casimir attraction).
- The plates should not have different surface potentials
- Ref: "Measurements of Attractive Forces Between Flat Plates“
(Sparnaay, 1958) Physica, 24 751-764
Effects of edgesshape of decay function is strongly dependent on size and separation of surfacesref:http://images.google.com/imgres?imgurl=http://www.sr.bham.ac.uk/yr4pasr/project/casimir/currentthumb.jpg&imgrefurl=http://www.sr.bham.ac.uk/yr4pasr/project/casimir/&h=275&w=275&sz=41&tbnid=Buy2QDUNZEvi6M:&tbnh=109&tbnw=109&hl=en&start=20&prev=/images%3Fq%3Dcasimir%2Beffect%26svnum%3D10%26hl%3Den%26lr%3D%26sa%3DG
Dist > 25µm: dome shape
The Casimir force occurs when virtual photons are restricted.
The force is reduced where virtual photons are diffracted into the gap between the plates
Unshaded areas correspond to higher Casimir forces
Casimir force is decreased at the edges of the plates
The Casimir force: FCon Microelectromechanical systems (MEMS)(PRL: H. B. Chan et al – Bell Lab & Lucent Tech –Published Oct 2001)
Mock set up
K= 0.019 Nm-1
Sphere radius = 100μm
dEQUILIBRIUM = 40nm
Torsional Spring constant: k=2.1 10-8 Nrad-1
Fund res. Freq. = 2753.47 Hz
I = 7.1 10-17 kgm2
System behaves linearly w/o sphere
z (equil dist sph-plate w/o FC)
Due to Electrostatic forceAdd a gold plated polystyrene sphere radius = 200μm
Freq shift ~ FC gradient (FC’)
ie: amplitude A has up to 3 roots:
Freq < resonant freq
Freq > resonant freq
H. B. Chan,* V. A. Aksyuk, R. N. Kleiman, D. J. Bishop, and Federico Capasso† Bell Laboratories, Lucent Technologies, Murray Hill, New Jersey 07974
Rep. Prog. Phys. 68 (2005) 201–236