Measurement of p-wave contacts using rf-spectroscopy in a ⁶Li 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).