The coherent interaction of Rydberg helium atoms with microwave fields in a λ / 4 superconducting coplanar waveguide resonator has been exploited to probe the spectral characteristics of an individual resonator mode. This was achieved by preparing the atoms in the 1s55s 3S1 Rydberg level by resonance enhanced two-color two-photon excitation from the metastable 1s2s 3S1 level. The atoms then traveled over the resonator in which the third harmonic microwave field, at a frequency of ω res = 2 π × 19.556 GHz, drove the two-photon 1s55s 3S1 → 1s56s 3S1 transition. By injecting a sequence of Ramsey pulses into the resonator and monitoring the coherent evolution of the Rydberg state population by state-selective pulsed electric field ionization as the frequency of the microwave field was tuned, spectra were recorded that allowed the resonator resonance frequency and quality factor to be determined with the atoms acting as microscopic quantum sensors.

中文翻译：

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里德堡原子-超导电路界面的腔增强拉姆齐光谱

里德堡氦原子与 λ/4 超导共面波导谐振器中微波场的相干相互作用已被用于探测单个谐振器模式的光谱特性。这是通过从亚稳态 1s2s 3S1 能级共振增强双色双光子激发制备 1s55s 3S1 里德堡能级中的原子来实现的。然后原子穿过谐振器，其中三次谐波微波场以 ω res = 2 π × 19.556 GHz 的频率驱动双光子 1s55s 3S1 → 1s56s 3S1 跃迁。通过将一系列拉姆齐脉冲注入谐振器，并在调谐微波场频率时，通过状态选择性脉冲电场电离监测里德堡态粒子群的相干演化，