Mobile impurity probing a two-dimensional superfluid phase transition

The use of atomically sized quantum systems as highly sensitive measuring devices represents an exciting and quickly growing research field. Here we explore the properties a quasiparticle formed by mobile impurity interacting with two-dimensional fermionic superfluid. energy is shown to be lowered superfluid pairing, this increases compressibility Fermi gas, thereby making it easier for perturb its surroundings. We demonstrate that fundamentally discontinuous nature superfluid-to-normal phase transition system leads rapid increase in around critical temperature. magnitude exhibits nonmonotonic behavior function pairing strength sizable maximum crossover region, where spatial extend Cooper pairs comparable interparticle spacing. Since measurable present experimental techniques, our results illustrate how impurities entangled their environment can serve useful probes nontrivial thermal correlations.