  The interplay of interactions, symmetries and gauge fields usually leads to
intriguing quantum many-body phases. To explore the nature of emerging phases,
we study a quantum Rabi triangle system as an elementary building block for
synthesizing an artificial magnetic field. We develop an analytical approach to
study the rich phase diagram and the associated quantum criticality. Of
particular interest is the emergence of a chiral-coherent phase, which breaks
both the $\mathbb{Z}_2$ and the chiral symmetry. In this chiral phase, photons
flow unidirectionally and the chirality can be tuned by the artificial gauge
field, exhibiting a signature of broken time-reversal symmetry. The
finite-frequency scaling analysis further confirms the associated phase
transition to be in the universality class of the Dicke model. This model can
simulate a broad range of physical phenomena of light-matter coupling systems,
and may have an application in future developments of various quantum
information technologies.
