Photons do not directly interact with magnetic fields. Recent progress in synthetic gauge fields have stimulated investigations in various fields. In this study, we explore the enclosed synthetic magnetic flux in a parity-time ($\mathcal{PT}$)-symmetric system of three coupled optical resonators; this flux suppresses the $\mathcal{PT}$ transition and affects the topological structure of $\mathcal{PT}$ transition points. Although the phase rigidities of the coalesced states no longer vanish at exceptional points (EPs), the orders of the EPs (which are affected by the magnetic flux) can be identified. At a three-state coalescence, the intensity of an initial excitation increases according to a power law, and at a two-state coalescence, the intensity can behave as invariant, oscillatory, quadratic increase, and oscillatory quadratic increase. Our findings provide an insight into the interplay between non-Hermiticity and the effective magnetic flux.

• Received 4 May 2017

DOI:https://doi.org/10.1103/PhysRevA.96.043821

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Published by the American Physical Society