Satellite Workshop

Casimir Forces and Their Measurement

Yale University, New Haven, CT, USA, August 10-11, 2009

For the past 60 years or so, the Casimir effect has enjoyed sustained interest, producing numerous papers and articles written by several generations of prominent physicists including E. M Lifshitz and J. Schwinger, to name a few. Various consequences and applications are found in a wide variety of domains in physics from particle, nuclear, atomic, and molecular physics to cosmology.

The first attempt of the Casimir force measurement has been historically credited to M. J. Sparnaay at Phillips Research Laboratories in Eindhoven in 1958, although, two years earlier, B. V. Derjaguin, I. I. Abrikosova, and E. M. Lifshitz has done a series of successful measurements of molecular attraction in a sphere-plane geometry. The difference between these two historic measurements was that Sparnaay had employed a pair of flat plates, the original configuration envisioned by Hendrik Casimir, and explicitly discussed his results in comparison with the Casimir's celebrated prediction ascribed to quantum vacuum fluctuation, while the discussion by Derjaguin and his co-workers centered around the molecular nature of the attraction (van der Waals interaction) in the simplified sphere-plane geometry.

The nuance in interpretation of the measured forces from the early results still persists, perhaps even more ostentatiously, in the field of modern-day precision measurements, creating a looming dichotomy between the Casimir force and the van der Waals force studies. Are these forces fundamentally different from each other? If so, what specific physical conditions there exist that could tell them apart? Investigations of the van der Waals force have been extensively performed since the advent of the atomic force microscope (AFM) in the early 90's and have become a primary topic of interest among biophysicists, chemical engineers, and material scientists using an AFM apparatus.

Interest in the Casimir force, on the other hand, have been rekindled shortly after the Steve Lamoreaux’s landmark experiment in 1997 at the University of Washington. Among physicists, the result has generated a host of interesting and yet controversial issues surrounding the properties of real materials and temperature corrections to the Casimir force in various geometrical configurations.

We expect that our satellite workshop will abridge the gap and gather leading AFM specialists, experimental physicists exploring the Casimir effect, and whoever is interested in undertaking force measurements involving both long-ranged (capacitive) and short-ranged (molecular) interactions between two metallic or dielectric plates, or combination of both. Contributions relevant to all aspects of force measurements, in particular of experimental results addressing the properties of real materials, are welcome.

Topics to be discussed during the workshop include, but are not limited to:

• effects of surface charges and contact potential variation,
• experimental procedures for distance and force calibrations,
• techniques to distinguish between capacitive and molecular forces in the presence of stray electric fields,
• issues related to interpreting results due to different experimental techniques, e.g., dynamic (frequency shift) vs. static (deflection) measurements, and
• discussion of fundamental interactions between two material objects in the context of the Lifshitz formalism.

Scientific sessions start on Monday, Aug 10th, 2009 and overlap with the NC-AFM conference on Aug 11th Tuesday with about 20 regular contributed talks (25 min each on Monday during the specialized Casimir sessions and 20 min each on Tuesday for general sessions on NC-AFM-based force spectroscopy) and two review talks. Workshop participation is free if attending the main conference. We encourage your participation and look forward to meeting you in New Haven.

Woo-Joong Kim, Udo Schwarz, Alex Sushkov, and Steve Lamoreaux , Casimir 2009 Workshop Organizers