We present the design and experimental demonstration of a single-layer atom chip with an additional wide U-shaped microwire to improve the loading of cold atoms into a magneto-optical trap (MOT). The optimized magnetic-field distribution created by the wide wire increases the trapping volume near the chip while keeping the device simple and operating with relatively low currents.
Experiments with 87Rb atoms show that the new configuration traps about 5 × 10⁷ atoms, which is roughly 3.5 times more than in the standard narrow-wire U-MOT. The atoms can then be efficiently transferred to a narrow-wire trap for further cooling and magnetic trapping with over 95% transfer efficiency.
The proposed design provides an efficient and compact cold-atom source, which is promising for portable quantum sensors, atomic clocks, and other chip-scale cold-atom devices.
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