7 research outputs found
Evidence for universal relations describing a gas with <i>p</i>-wave interactions
Thermodynamics provides powerful constraints on physical and chemical systems
in equilibrium. However, non-equilibrium dynamics depends explicitly on
microscopic properties, requiring an understanding beyond thermodynamics.
Remarkably, in dilute gases, a set of universal relations is known to connect
thermodynamics directly with microscopic properties. So far, these "contact"
relations have been established only for interactions with -wave symmetry,
i.e., without relative angular momentum. We report measurements of two new
physical quantities, the "-wave contacts", and present evidence that they
encode the universal aspects of -wave interactions through recently proposed
relations. Our experiments use an ultracold Fermi gas of K, in which
-wave interactions are suppressed by polarising the sample, while -wave
interactions are enhanced by working near a scattering resonance. Using
time-resolved spectroscopy, we study how correlations in the system develop
after "quenching" the atoms into an interacting state. Combining
quasi-steady-state measurements with new contact relations, we infer an
attractive -wave interaction energy as large as half the Fermi energy. Our
results reveal new ways to understand and characterise the properties of a
resonant -wave quantum gas.Comment: Minor corrections to methods & supplement