Observation of high partial-wave Feshbach resonances in $^{39}$K Bose-Einstein condensates

TL;DR

This paper reports the observation of high partial-wave Feshbach resonances in $^{39}$K Bose-Einstein condensates, revealing new resonances induced by dipolar interactions that enable tunable interactions for many-body physics studies.

Contribution

The study experimentally identifies and characterizes high partial-wave Feshbach resonances in $^{39}$K, supported by multichannel quantum-defect theory calculations, expanding understanding of interaction control in BECs.

Findings

Observation of multiple high partial-wave Feshbach resonances in $^{39}$K.

Identification of dipolar spin-spin interaction as the mechanism for these resonances.

Confirmation of specific d- and g-wave resonances via MQDT calculations.

Abstract

We report the new observation of several high partial-wave (HPW) magnetic Feshbach resonances (FRs) in $^{39}$K atoms of the hyperfine substate $\left|F=1,m_{F}=-1\right\rangle$. These resonances locate at the region between two broad $s$-wave FRs from 32.6 G to 162.8 G, in which Bose-Einstein condensates (BECs) can be produced with tunable positive scattering length obtained by magnetic FRs. These HPW FRs are induced by the dipolar spin-spin interaction with s-wave in the open channel and HPW in the closed channel. Therefore, these HPW FRs have distinct characteristics in temperature dependence and loss line shape from that induced by spin-exchange interaction with HPWs in both open and closed channels. Among these resonances, one $d$-wave and two $g$-wave FRs are confirmed by the multichannel quantum-defect theory (MQDT) calculation. The HPW FRs have significant applications in many-body physics dominated by HPW pairing.