Complex Berry phase dynamics in PT-symmetric coupled waveguides

Rosie Hayward*, Fabio Biancalana

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)
156 Downloads (Pure)


We show that the analog of the geometric phase for non-Hermitian coupled waveguides with PT symmetry and at least one periodically varying parameter can be purely imaginary, is hence no longer a true phase and instead a real multiplier, and will consequently result in the amplification of Floquet sidebands in the system. The sideband 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 sidebands are magnified (becoming virtually unstable) as the exceptional point of the system is approached, and nonadiabatic effects begin to appear. Because the system cannot evolve adiabatically in the vicinity of the exceptional point, PT symmetry will be observed breaking earlier than theoretically predicted.

Original languageEnglish
Article number053833
JournalPhysical Review A
Issue number5
Publication statusPublished - 20 Nov 2018

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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