We experimentally and theoretically show that the electron energy spectra strongly depend on the relative helicity in highly intense, circularly polarized two-color laser fields which is an unexpected finding. The employed counter-rotating two-color (CRTC) fields and the co-rotating two-color (CoRTC) fields are both a superposition of circularly polarized laser pulses at a central wavelength of 390 nm and 780 nm (intensitiy ratio $I_{390}/I_{780}\approx 250$). For the CRTC field, the measured electron energy spectrum is dominated by peaks that are spaced by 3.18 eV (corresponds to the photon energy of light at a wavelength of 390 nm). For the CoRTC field, we observe additional energy peaks (sidebands). Using our semi-classical, trajectory-based models, we conclude that the sideband intensity is modulated by a sub-cycle interference, which sensitively depends on the relative helicity in circularly polarized two-color fields.
We demonstrate a simple method to obtain accurate optical waveforms with a GHz-level programmable modulation bandwidth and Watt-level output power for wideband optical control of free atoms and molecules. Arbitrary amplitude and phase modulations are transferred from microwave to light with a low-power fiber electro-optical modulator. The sub-milliWatt optical sideband is co-amplified with the optical carrier in a power-balanced fashion through a tapered semiconductor amplifier (TSA). By automatically keeping TSA near saturation in a quasi-continuous manner, typical noise channels associated w…
Low-phase-noise and pure-spectrum Raman light is vital for high-precision atom interferometry by two-photon Raman transition. A preferred and prevalent solution for Raman light generation is electro-optic phase modulation. However, phase modulation inherently brings in double sidebands, resulting in residual sideband effects of multiple laser pairs beside Raman light in atom interferometry. Based on a well-designed rectangular fiber Bragg grating and an electro-optic modulator, optical single-sideband modulation has been realized at 1560 nm with a stable suppression ratio better than -25 dB de…
We present a new electro-optic modulation technique that enables a single laser diode to realize a cold-atom source and a quantum inertial sensor based on matter-wave interferometry. Using carrier-suppressed dual single-sideband modulation, an IQ modulator generates two optical sidebands from separate radio-frequency (rf) signals. These sidebands are controlled independently in frequency, phase, and power using standard rf components. Our laser source exhibits improved rejection of parasitic sidebands compared to those based on phase modulators, which generate large systematic shifts in atom i…
We describe a novel pulsed magnetic gradiometer based on the optical interference of sidebands generated using two spatially separated alkali vapor cells. The sidebands are produced with high efficiency using parametric frequency conversion of a probe beam interacting with $^{87}$Rb atoms in a coherent superposition of magnetically sensitive hyperfine ground states. Interference between the sidebands generates a low-frequency beat note whose frequency is determined by the magnetic field gradient between the two vapor cells. In contrast to traditional magnetic gradiometers, our approach provide…
We report a joint experimental and theoretical study of a three-sideband (3-SB) modification of the "reconstruction of attosecond beating by interference of two-photon transitions" (RABBIT) setup. The 3-SB RABBIT scheme makes it possible to investigate phases resulting from interference between transitions of different orders in the continuum. Furthermore, the strength of this method is its ability to focus on the atomic phases only, independent of a chirp in the harmonics, by comparing the RABBIT phases extracted from specific SB groups formed by two adjacent harmonics. We verify earlier pred…
Intra- and intercycle interference of angle-resolved electron emission in laser assisted XUV atomic ionization
本文对红外激光作用下超紫外脉冲电离氢原子进行了理论研究。激光辅助光电子效应问题通常采用成熟的理论来描述。然而，由Maquet等人在Journal of Modern Optics 54，1847（2007）中首次提出的公知的软光子近似和Kazansky在Phys.Rev.A 82，033420（2010）中的理论完全不能预测与偏振方向优先的电子发射。利用一个简单的半经典模型，研究了两个光场均为同向线偏振时光电子的角分辨能量分布。我们彻底分析和表征两个不同的发射区域中的角能域：（i）平行状区域的贡献的两个经典的轨迹每个光学周期和（ii）的类椭圆形区域的贡献的四个经典的轨迹每个光学周期。我们表明，我们的半经典模型是能够评估的角度分辨光电子谱的干涉图案在两个不同的上述区域。来自不同光学激光周期的电子轨迹引起称为边带的与角度无关的周期间干涉。这些边带被来自同一光周期中产生的电子轨道的干涉的角度依赖性粗粒结构调制。我们显示我们的半经典模型的准确性作为IR和XUV脉冲之间的时间延迟的函数，也作为激光强度的函数，通过比较半经典预测的角度分辨光电子光谱与连续扭曲波强场近似和从头算解的时间依赖的薛定谔方程。
Floquet-sideband-enhanced shortwave electrometry with Rydberg atoms
Xi’an Jiaotong University（西安交通大学）；Nanjing University（南京大学）；Beijing Institute of Radio Metrology and Measurement（北京无线电计量测试研究所）；East China Normal University（华东师范大学）；Hefei National Laboratory（合肥国家实验室）；University of Arkansas（阿肯色大学）
