Higher-order exceptional points and asymmetric soliton scattering with triple-well PT-symmetry potential in an atomic gas

We propose a physical scheme to realize a parity-time (PT)-symmetric triple-well potential in a coherent atomic gas and investigate the emergence of higher-order exceptional points (EPs). Through careful parameter tuning, we successfully identify a third-order EP (EP3), observing its characteristic cube-root response to perturbations—a key signature distinguishing it from second-order EPs (EP2). Notably, EP3 exhibits significantly enhanced sensitivity, underscoring its potential for advancing quantum information technologies. Furthermore, we show that the imaginary part of the nonlinear PT potential critically governs PT phase transitions and dynamically reshapes the phase diagram. Our system also supports stable optical solitons, whose properties can be precisely controlled by tuning the interplay between linear and nonlinear PT potentials. When these potentials act as defects, soliton scattering displays strongly asymmetric behavior, directly adjustable via the potentials’ imaginary components. These findings open new avenues for applications in optical switch, optical sensing, and high-precision information transmission.