Polaritons for testing the universality of an impurity in a Bose-Einstein condensate

Universality is a fundamental concept in physics that allows for the description of properties of systems that are independent of microscopic details. In this work, we show that polaritons in a Bose-Einstein condensate (BEC) are a suitable platform to probe in a non-demolition way the universal high-energy spectrum of an impurity strongly coupled to a BEC. Based on a field theory that includes the two-body correlations at the exact level we demonstrate that under appropriate conditions, the damping rate of slow-light propagation reveals the high-energy universal tail in the polaron spectrum.