Quantum friction theory drags experiments toward realization

Quantum friction occurs as a tiny particle moves with respect to a macroscopic body in vacuum. Adding the material body alters the quantum fluctuations and creates a drag force on the particle.

Experiments point towards a confirmation of this force but remain controversial. Reiche et al. discussed the theory and history behind quantum friction, as well as possibilities for making its detection attainable.

“The theory part, so far, is not completely clarified,” said author Daniel Reiche. “We are talking about interacting quantum field theories that are strongly coupled to the environment in nonequilibrium statistical physics. You also have to incorporate atomic physics, as well as material physics, and brew that all together to make a working and tasty soup.”

In a simple estimate, quantum friction scales inversely with the distance to the power of 10. Therefore, the closer the particle comes to the material surface, the stronger the force. However, that also makes detection more difficult at larger distances.

“This might become relevant at some point in nanotechnologies where you have very close distances to surfaces and where those fluctuations could play a very strong role,” said author Kurt Busch.

The team is working to find the sweet spot for system geometries and materials to improve the likelihood of measurements. Experimentally confirming the force would have implications for many phenomena, from physics to cosmology.

“By starting with a relatively simple system, we can get lots of information about many different aspects of physics, from the very small to the very big,” said author Francesco Intravaia.

Source: “Wading through the void: Exploring quantum friction and nonequilibrium fluctuations,” by D. Reiche, F. Intravaia, and K. Busch, APL Photonics (2022). The article can be accessed at https://doi.org/10.1063/5.0083067 .