光纤陀螺仪的物质波模拟
Matter Wave Analog of a Fiber-Optic Gyroscope
AI总结：
本文在激光波导中实现二维 Sagnac 原子干涉仪，作为光纤陀螺仪的物质波模拟，利用 Bragg 脉冲和 Delta-kick 冷却实现 0.8 mm² 包围面积，并首次测量其 Allan 偏差，证明长时间平均下噪声可降至地球自转速率以下。
摘要：
将原子干涉仪中传播的波包限制在波导内，可以在保持高灵敏度的同时大幅缩小器件尺寸。我们实现了一种二维 Sagnac 原子干涉仪，其中玻色凝聚的 $^{87}$Rb 原子在由准直激光束形成的紧束缚波导内传播，这是光纤陀螺仪（FOG）的物质波模拟。凝聚体通过一系列 Bragg 脉冲进行分束、反射和合束，同时波导横向移动，使波包轨迹包围一个面积。使用 Delta-kick 冷却制备低密度原子波包，温度为 \SI{3}{\nano \kelvin}。低密度降低了原子间相互作用的影响，而低温限制了波包在干涉仪循环期间的膨胀。有效包围面积为 $0.8 \text{mm}^2$，平均条纹对比度为 20%，底层对比度高达 60%。平均对比度降低的主要来源是光学元件机械振动引起的相位噪声。我们首次给出了此类原子旋转传感器的 Allan 偏差测量结果，表明干涉仪相位噪声随平均时间 $τ$ 以 $τ^{-1/2}$ 的规律下降，$τ$ 最长可达 10,000 秒。经过 30 分钟的平均后，统计噪声降至地球自转速率以下。
英文摘要：
Confining the propagating wavepackets of an atom interferometer inside a waveguide can substantially reduce the size of the device while preserving high sensitivity. We have realized a two-dimensional Sagnac atom interferometer in which Bose-condensed $^{87}$Rb atoms propagate within a tight waveguide formed by a collimated laser beam, a matter wave analog of the fiber optic gyro (FOG). The condensate is split, reflected, and recombined with a series of Bragg pulses while the waveguide moves transversely so that the wavepacket trajectories enclose an area. Delta-kick cooling is used to prepare low-density atomic wavepackets with a temperature of \SI{3}{\nano \kelvin}. The low density reduces the impact of interatomic interactions, while the low temperature limits the expansion of the wavepacket during the interferometer cycle. The effective enclosed area is $0.8 \text{mm}^2$ with an average fringe contrast of 20\% and underlying contrast up to 60\%. The main source of the reduced average contrast is phase noise caused by mechanical vibrations of the optical components. We present the first measurement of Allan deviation for such an atom rotation sensor, showing that the interferometer phase noise falls with averaging time $τ$ as $τ^{-1/2}$ for $τ$ up to 10,000 seconds. The statistical noise falls below the Earth rotation rate after 30 minutes of averaging.
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