Fig. 2: Floquet quasi-energy spectrum, PT-symmetry phase transition and dynamic evolution of the Floquet PT-symmetric system.
a Imaginary (blue) and real (red) parts of the quasi-energy spectrum of the effective Hamiltonian Heff for the Floquet PT-symmetric systems. where the breaking of PT-symmetry appears at the EP with small Γ. b Real part energy spectra and its translation in frequency for ordinary PT-symmetric system. The dashed line denotes its imaginary part of the energy spectrum. c, d Evolution of the amplification |ξam〉 and suppression |ξsu〉 modes of the two outputs of the PT-symmetric system (total intensity in the inset). They have the same magnitude in two locations but different phases on the Bloch sphere. Here Γ = 0.2 and T = 5π/(2√6) (see details in SI-3(S10)). e Imaginary (blue) and real (red) quasi-energy of Floquet PT-symmetric system versus periodicity Tκ. f Simulated (based on beam-propagation method) light output intensity versus length of Floquet periodicity in the waveguide array.
