Researchers from the Institute of Applied Physics (IAP) at the University of Bonn have investigated the effects of dimensionality on gases made up of light particles, or photons. Their study draws an analogy between filling a swimming pool and a narrow gutter with water to illustrate how the dimensionality of a system affects its behavior. By cooling and concentrating photons in a confined space, the researchers aimed to create a photon gas that could exhibit unique properties based on its dimensionality.

In their experiment, the team used a tiny container filled with a dye solution and excited it with a laser, causing the photons to bounce between reflective walls. By applying a transparent polymer with microscopically small protrusions to the container’s surfaces, they were able to manipulate the dimensionality of the photon gas. As the dimensions became more confined, the gas behaved increasingly one-dimensionally, similar to how waves behave in a narrow gutter.

The research revealed that, unlike two-dimensional gases with a defined phase transition point, one-dimensional photon gases lack a precise condensation point due to significant thermal fluctuations. These fluctuations disrupt the uniform behavior of the gas, smearing out the phase transition. This pioneering work enhances our understanding of the transition between two-dimensional and one-dimensional photon gases and may lead to new applications in quantum optics and beyond.

The polymers applied to the reflective surface trap the photon gas in a parabola of light. The narrower this parabola is, the more one-dimensionally the gas behaves. (Artistic illustration courtesy: IAP/Uni Bonn)

Click here to view the press release of the University of Bonn.