Chongfan Technology
News
23
2026
-
07
The Shanghai Institute of Optics and Fine Mechanics has made progress in the precise control of cold-atom velocity vectors.
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Recently, the research team led by Researcher Wei Rong at the Department of Frontier Interdisciplinary Studies in Optoelectronics of the Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, has achieved a significant breakthrough in the precise manipulation of cold atoms. They have developed a three-dimensional precision control method for the launch velocity vector of a cold atomic cloud, based on independently adjustable moving optical molasses. The related findings, titled “Precise control of launch velocity vector for cold atomic cloud based on moving optical molasses,” were published in Applied Physics Letters.
The cold‑atom external state, characterized by velocity, is a key parameter for quantum control of cold atoms and significantly impacts the measurement accuracy of high‑precision quantum interferometric devices such as atomic fountain clocks, gravimeters, and gyroscopes. Conventional methods for controlling the direction of the cold‑atom ejection velocity rely on high‑precision mechanical and optical alignment; once aligned, only the magnitude of the velocity can be adjusted. To modify the relative angle between the velocity vector and the gravitational field, current approaches involve fine‑tuning the overall tilt of the apparatus. These methods are cumbersome to assemble and align, with limited control precision. To address these challenges, researchers have proposed an all‑optical scheme for vector‑based velocity control. By independently tuning the relative detunings of three pairs of orthogonally oriented counter‑propagating cooling beams, they achieve precise, independent manipulation of the three spatial components of the cold‑atom cloud’s velocity. The team experimentally demonstrated this approach on a standard rubidium atomic fountain clock. The method enables real‑time, high‑precision velocity regulation during normal operation of the fountain, with ejection‑velocity accuracy better than 62 μm/s. Analysis indicates that intensity fluctuations in the counter‑propagating beams—on the order of 3%—are the primary source of vector‑accuracy degradation; carefully balancing the power of these beams could potentially bring velocity‑vector control precision down to 1 μm/s. Furthermore, the researchers demonstrated the technique’s capability to measure and correct tilt‑induced deviations in the fountain clock, reducing the angle between the emitted atom cloud’s trajectory and the vertical to less than 0.1 mrad after correction.
This all-optical control method boasts significant advantages, including simple operation, rapid response, high control precision, and a broad dynamic range. It not only holds potential for applications in high‑precision quantum interference experiments—such as time‑frequency metrology, gravitational field sensing, measurement of physical constants, and tests of fundamental physical principles—but also promises to serve as an exceptionally versatile technique for cold‑atom transport, thereby facilitating a wide array of experiments involving cold‑atom preparation and quantum coherence.
Figure 1 (a) Schematic diagram of the principle for three-dimensional precise velocity control of cold atoms, and (b) schematic illustration of measuring the velocity vector of cold atoms using a falling‑signal technique.
Figure 2. Experimental results of the atomic cloud ejection velocity. (a), (b), (d), and (e) show the horizontal distribution of the cold atomic cloud, obtained by scanning the horizontal velocity at two different launch heights; (c) determines the center of the atomic cloud’s ejection velocity; (f) illustrates the correction for the fountain clock’s tilt angle, compared with measurements from an inclinometer.
Source: Shanghai Institute of Optics and Fine Mechanics
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