Li cold atom system*

Tan’s contact establishes universal relations that link numerous macroscopic thermodynamic quantities to the microscopic few body interactions, regardless of particle species, density, temperature or interactions strength. These universal relations enable a systematic understanding of thermodynamics in systems with two-body contact interactions. While the universal relations have been proven for s-wave systems through versatile experiments, the measurements of p-wave contacts have so far been limited to ⁴⁰K atoms [1]. Consequently, a second dataset from different atomic species is essential to further uncover the universal characteristics of p-wave interactions. In particular, understanding how the intrinsic differences in the effective range R manifest in the universal properties of p-wave contacts is of significant physical importance.

Here, I present measurements of the p-wave contact in a ⁶Li atom system near a 159 G p-wave Feshbach resonance. Our experiment utilizes radio-frequency (rf) spectroscopy to extract the contacts  and  from high-frequency tails of the spectra. We measure these contacts at various magnetic fields and find that their behavior agrees well with virial expansion expression at large magnetic field detunings. A direct comparison with previous measurements in ⁴⁰K atoms suggests that the universal relations hold across different atomic species. However, the magnitude of the p-wave contacts differs due to the intrinsic difference in the effective range parameter, in contrast to the s-wave contact. Our results pave the way for the determination of thermodynamic quantities for atoms with strong p-wave interactions.

[1] C. Luciuk, et al,  Nat. Phys. 12, 599 (2016).