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Russian physicists put forward new way to calculate fluctuation forces

MOSCOW, October 31. /TASS/ Professors Galina Klimchitskaya and Vladimir Mostepanenko from Peter the Great Saint Petersburg Polytechnic University (SPbPU) have suggested an alternative approach for calculating fluctuation forces in microdevices, said the media center of SPbPU.

The new method has been successfully approved experimentally and will be helpful in creating various thin-film coatings and graphene-based devices where the proper account for dispersion forces is of primary importance.

"In 2016, American scientists from Indiana University and Purdue University Indianapolis carried out a landmark experiment confirming the forecasts of Russian physicists," the press release reported. Up to that time, the task of evaluating fluctuation forces had remained unsolved, because the results gained from the standard approaches of quantum statistical physics contradicted the experimental data.

What are fluctuation forces and why it is important to calculate them?

Caused by quantum effects, the fluctuation forces (Van-der-Waals forces, Casimir forces) act between objects located in close proximity. They arise from a vacuum and appear due to very small quantum-mechanical deviations (fluctuations) of electrical and magnetic fields values which cannot be eliminated and fixed even at absolute zero.

When dealing with objects sized less than several hundred nanometers, one needs to take into account the fluctuation forces to reproduce their properties and characteristics, since at this scale the impact of Casimir forces on the overall behavior of the system becomes essential.

Exemplarily, the Casimir forces can lead to the coalescing of the microdevice’s elements.

What did the Russian scientists put forward?

According to the approach introduced by the SPbPU researchers, the materials show different responses when exposed to the real electromagnetic fields of non-zero strength or to the quantum fluctuations characterized by zero mean values of fields. In particular, the quantum fluctuations do not cause the appearance of real currents in metals and consequently, do not heat them. This difference forms the key idea to the new statistical approach of calculating fluctuation forces.

The basics of this unique method have been presented in a series of articles in leading international journals: Physical Review Letters, Physical Review A, and Physical Review B, with the last two articles being published in September and October 2016. The study’s results can be useful for developing various microdevices, for example, for biomedical purposes.