Complex Berry phase instability in PT-symmetric coupled waveguides

Abstract

We show that the analogue of the geometric phase for non-Hermitian coupled waveguides with PT-symmetry and at least one periodically varying parameter can be purely imaginary, and will consequently result in the manifestation of an instability in the system. The instability peaks seen in the spectrum of the system's eigenstates after evolution along the waveguides can be directly mapped to the spectrum of the derivative of the geometric function. The instabilities are magnified as the exceptional point of the system is approached, and non-adiabatic effects begin to appear. As the system cannot evolve adiabatically in the vicinity of the exceptional point, PT-symmetry will be observed breaking earlier than theoretically predicted.

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Cited by in corpus (5)

• Complex Berry phase and imperfect non-Hermitian phase transitions
• The non-Hermitian geometrical property of 1D Lieb lattice under Majorana's stellar representation
• PT-symmetric dynamical confinement: Fermi acceleration, quantum force and Berry phase
• Stability of time-periodic $\mathcal{P}\mathcal{T}$ and anti-$\mathcal{P}\mathcal{T}$-symmetric Hamiltonians with different periodicities
• Monopole Antimonopole Instability in Non-Hermitian Coupled Waveguides