Quantum tricriticality of bosonic atomic-molecular mixtures with Feshbach coupling

We identify that coherent interconversion can stabilize bosonic atomic-molecular mixtures by establishing a comprehensive and analytical phase diagram, which can accommodate up to two tricritical points (TPs) with one being intrinsic and the other being conditional. By varying the interaction parameters, the topology of the phase diagram gets modified while changing the number of TPs. We master the quantum tricriticality and concrete signals of the phase transition for this system. Notably, we show that the sound velocity vanishes as the atomic-molecular superfluid phase touches on the border of the phase separation lines.. Correlation functions such as pairing amplitudes and density (spin density) structure factors exhibit characteristic behaviors when the system crosses the phase transitions. Our work paves the way for future advancement toward understanding the salient physics of atom-molecular mixtures.