发表机构
Chongqing University; Xi’an Jiaotong University; China University of Mining and Technology; City University of Hong Kong（重庆大学; 西安交通大学; 中国矿业大学; 香港城市大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过Floquet杂化在合成频率维度实现恒定频率振荡，突破传统空间PT破缺相限制，并实验验证了其机制。
AI 中文摘要
恒定频率振荡通常与空间耦合的PT对称二聚体的破缺相相关，在该相中，本征频率形成具有固定实部的复共轭对。本工作表明，类似的锁定可以来自合成频率维度中的Floquet杂化。周期性增益-损耗调制将频谱折叠成由驱动频率Ω间隔的副本。相邻副本之间的耦合在Floquet布里渊区边缘打开了额外的实部简并。在ω0±Ω/2处的杂化Floquet模式需要最小增益，因此被选择用于自激振荡。一个具有JFET时变负电阻的Floquet PT对称电路证实了这一预测。观察到的恒定频率振荡包含两个幅度相当的频率分量，它们由调制频率分隔，这识别出其来源于Floquet杂化，而非普通的PT对称破缺或色散平坦化。更广泛地，一旦建立了适当对称约束的谱简并，自持频率钉扎可以超越传统的空间PT破缺相而出现。
英文摘要
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 $ω_0\pmΩ/2$ 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.
