发表机构
Johns Hopkins University; Indian Institute of Science; Defence Institute of Advanced Technology (Deemed University); University of Bristol; Indian Institute of Technology Guwahati（约翰斯·霍普金斯大学; 印度科学学院; 国防先进技术研究所（认定大学）; 布里斯托大学; 印度理工学院古瓦哈提分校）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过里德伯原子EIT系统中的外差谐波产生，实现相位倍增效应，为微波相位敏感探测提供了增强相位响应的新方法。
AI 中文摘要
我们研究了在涉及里德伯态并由两个微波场以零差构型驱动的电磁感应透明（EIT）阶梯系统中，由非线性相互作用引起的探针激光吸收中的高阶谐波的产生与表征。我们表征了所产生谐波的幅度和相位随所施加微波场的相对频率和相位的变化关系。第n次谐波的相位满足关系φ_n=nφ，展示了相位倍增效应，并表明高阶谐波可能为相位敏感测量提供增强的相位响应。我们进一步表征了谐波幅度和带宽，发现测得的带宽显著大于里德伯态固有线宽，这与实验条件下的功率展宽一致。实验观测得到了密度矩阵计算的支持，该计算重现了所测谐波响应的关键特征。
英文摘要
We investigate the generation and characterization of higher-order harmonics in the probe-laser absorption arising from nonlinear interactions in an electromagnetically induced transparency (EIT) ladder system involving Rydberg states and driven by two microwave fields in the heterodyne configuration. We characterize the amplitude and phase of the generated harmonics as a function of the relative frequency and phase of the applied microwave fields. The phase of the $n^{\mathrm{th}}$ harmonic follows the relation $ϕ_n=nϕ$, demonstrating phase multiplication and suggesting that higher-order harmonics may offer an enhanced phase response for phase-sensitive measurements. We further characterize the harmonic amplitudes and bandwidths and find that the measured bandwidths are significantly larger than the intrinsic Rydberg-state linewidth, consistent with power broadening under the experimental conditions. The experimental observations are supported by density-matrix calculations, which reproduce the key features of the measured harmonic response.
Comments8 pages, 14 figures, 1 table
