In the world of many-body physics, it is common knowledge that the number of accessible dimensions profoundly influences the physical behaviour of a system, leading to the emergence of different states of matter at low dimensions. In lower dimensions, fluctuations increase and lead to the suppression of long-range order. For example, in bosonic gases, Bose–Einstein condensation in one dimension requires stronger confinement than in two dimensions.
Our team at the University of Bonn together with colleagues from the RPTU Kaiserslautern have now studied the dimensional crossover in a quantum gas of light from 2D to 1D in a harmonically trapped photon gas. The photons are trapped in a dye microcavity where polymer nanostructures provide the trapping potential for the photon gas. The polymer nanostructures of up to 325nm height were directly deposited on top of the cavity mirrors by employing a two-photon direct laser writing technique that offers a high transverse spatial resolution of around 100nm. By varying the aspect ratio of the harmonic trap, we could thus tune from isotropic two-dimensional confinement to an anisotropic, highly elongated one-dimensional trapping potential. Along this transition, we determine the caloric properties of the photon gas and find a softening of the second-order Bose–Einstein condensation phase transition observed in two dimensions to a crossover behaviour in one dimension. The study is published in the journal Nature Physics.
Read the manuscript "Dimensional crossover in a quantum gas of light" here. The full text is available without subscription under this Sharedit link.
For a more general perspective on the study, check out the blog post 'Behind the Paper: Lazy light in 1D" by Kirankumar Karkihalli Umesh and Frank Vewinger.