基于三线阿基米德螺线环形波导的原子芯片陀螺仪

按照物质波传输的方式，原子陀螺仪分为自由空间型和导引型两类。实验上，自由空间型原子陀螺仪比导引型易于实现。但自由空间型体积庞大而且动态旋转信号容易损失。因此，研制环路固定的导引型原子陀螺仪，是冷原子物理和陀螺仪领域所共同关注的研究方向。国际上提出利用磁阱形成环形物质波导的方案很多，但真正能实现陀螺效应的环形波导方案鲜有报道。DARPA产生环形物质波导的方式是调制方式的双层原子芯片方案。双层芯片加工难度很大，而且该方案存在电流切换等缺点。因此，我们提出了可在单层芯片上刻蚀的三线阿基米德螺线形状的布线结构。该结构避免了引线缺口，可形成封闭的环形势阱。通过时间轨道平均势的方式对芯片导线直接加载交流调制就可移除导引中心的磁场零点，进而形成光滑封闭的物质波导环路。再利用Raman-Nath双驻波激光脉冲实现环形波导中超冷原子的相干分束和合束，即可获取旋转信息。

Under the same loop area case, the sensitivity of atomic gyroscope based on Sagnac effect is 10 orders higher than that of optical gyroscope. According to the mode of matter wave propagation, atomic gyroscope can be divided into two types-- free space type and guided one. Experimentally, free space atomic gyroscope is easier to realize than guided one, and its precision is also higher. However, from the point of view of instrumentation, free space type is bulky. In August 2018, DARPA proposed how to integrate high-precision guided cold atomic gyroscopes on photonics integrated chips, which highlighted another competitive advantage of guided atomic gyroscopes. There are many schemes of matter waveguide, but there are few reports about ring trap schemes that can achieve gyroscopic effect. The way DARPA generates ring matter waveguide in the past probably adopts the current modulation scheme of double-layer atomic chip. It is very difficult to fabricate double-layer chip, and the scheme has some shortcomings such as current switching between the two layer wires. Therefore, we propose the three Archimedes spiral wires layout which can be etched on a single-layer chip. The structure has no trapping notch caused by the input and output ports, and then can form an enclosed loop trap for guiding neutral atoms. By applying the current modulation method based on the time-orbiting-potential principle to our structure, the zero point of the magnetic field in the guidance center can be removed, thus a smooth enclosed and harmonic ring matter waveguide trap is formed. By coherently splitting the atom cloud in the toroidal magnetic guide and combining the atom beams after the coherently guiding process in the wave guide, the rotation information can be obtained based on the interferometric signal. The coherent splitting and combining scheme is a double-pulse standing optical wave in the Raman-Nath regime.