Beyond the PT-Broken Phase: Constant-Frequency Oscillation from Floquet Hybridization
Abstract
Constant-frequency oscillation is usually tied to the broken phase of a spatially coupled PT-symmetric dimer, where the eigenfrequencies form a complex-conjugate pair with a fixed real part. This work shows that an analogous locking can instead come from Floquet hybridization in a synthetic frequency dimension. Periodic gain--loss modulation folds the spectrum into replicas spaced by the drive frequency Ω. Coupling between neighboring replicas opens an additional real-part degeneracy at the edge of the Floquet Brillouin zone. The hybridized Floquet mode at ω0±Ω/2 requires the minimum gain and is therefore selected for the self-oscillation. A Floquet PT-symmetric circuit with a JFET time-varying negative resistance confirms the prediction. The observed constant-frequency oscillation contains two frequency components of comparable amplitude, separated by the modulation frequency, which identifies its origin from Floquet hybridization rather than ordinary PT-symmetry breaking or dispersion flattening. More broadly, once a suitably symmetry-constrained spectral degeneracy is established, self-sustained frequency pinning can arise beyond the conventional spatial PT-broken phase.
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BibTeX
@misc{gao2026beyond,
title = {{Beyond the PT-Broken Phase: Constant-Frequency Oscillation from Floquet Hybridization}},
author = {Xiaoke Gao and Xiaoyin Sha and Xunyan Sun and Xianglin Hao and Huaiqing Zhang and Tianyu Dong},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.03560},
eprint = {2610.03560},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.03560},
}
RIS
TY - UNPB
TI - Beyond the PT-Broken Phase: Constant-Frequency Oscillation from Floquet Hybridization
AU - Xiaoke Gao
AU - Xiaoyin Sha
AU - Xunyan Sun
AU - Xianglin Hao
AU - Huaiqing Zhang
AU - Tianyu Dong
PY - 2026
DA - 2026/10/02
PB - arXiv
DO - 10.48550/arxiv.2610.03560
UR - https://arxiv.org/abs/2610.03560
AB - Constant-frequency oscillation is usually tied to the broken phase of a spatially coupled PT-symmetric dimer, where the eigenfrequencies form a complex-conjugate pair with a fixed real part. This work shows that an analogous locking can instead come from Floquet hybridization in a synthetic frequency dimension. Periodic gain--loss modulation folds the spectrum into replicas spaced by the drive frequency Ω. Coupling between neighboring replicas opens an additional real-part degeneracy at the edge of the Floquet Brillouin zone. The hybridized Floquet mode at ω_0±Ω/2 requires the minimum gain and is therefore selected for the self-oscillation. A Floquet PT-symmetric circuit with a JFET time-varying negative resistance confirms the prediction. The observed constant-frequency oscillation contains two frequency components of comparable amplitude, separated by the modulation frequency, which identifies its origin from Floquet hybridization rather than ordinary PT-symmetry breaking or dispersion flattening. More broadly, once a suitably symmetry-constrained spectral degeneracy is established, self-sustained frequency pinning can arise beyond the conventional spatial PT-broken phase.
ER -