Strongly Interacting Bose Gases near a $d$-wave Shape Resonance

Abstract

Many unconventional quantum matters, such as fractional quantum Hall effect and $d$-wave high-Tc superconductor, are discovered in strongly interacting systems. Understanding quantum many-body systems with strong interaction and the unconventional phases therein is one of the most challenging problems in physics nowadays. Cold atom systems possess a natural way to create strong interaction by bringing the system to the vicinity of a scattering resonance. Although this has been a focused topic in cold atom physics for more than a decade, these studies have so far mostly been limited for $s$-wave resonance. Here we report the experimental observation of a broad $d$-wave shape resonance in degenerate ${}^{41}$K gas. We further measure the molecular binding energy that splits into three branches as a hallmark of $d$-wave molecules, and find that the lifetime of this many-body system is reasonably long at strongly interacting regime. From analyzing the breathing mode excited by ramping through this resonance, it suggests that a quite stable low-temperature atom and molecule mixture is produced. Putting all the evidence together, our system offers great promise to reach a $d$-wave molecular superfluid.