Radiation pressure is often thought of as the force of impinging photons, the quanta of light, on a surface. Interestingly, in the total darkness, the simple existence of the field even devoid of any photon applies a small pressure on surfaces, which is an effect of its quantum fluctuations. This so-called vacuum force is revealed in a Casimir setup, where two mirrors face each other at a very close distance. Some wavelengths are forbidden in the space between the mirrors and the vacuum force on mirrors from the interior sides facing each other is reduced compared to that exerted on the exterior sides, which pulls the mirrors together. Surprisingly, this force has never been observed between superconducting mirrors, although it would give useful insight into the nature of vacuum forces. I propose to use two tiny, 100-nanometers-thick aluminum layers spaced by a thin vacuum gap, cooled at milli-Kelvin temperatures to reach superconductivity, and observe this effect for the first time.

2021

2025