High-precision gyroscopes in space are essential for fundamental physics research and navigation. Due to its potential high precision, the cold atom gyroscope is expected to be the next generation of gyroscopes in space. Here, we report the first realization of a cold atom gyroscope, which was demonstrated by the atom interferometer installed in the China Space Station (CSS) as a payload. By compensating for CSS's high dynamic rotation rate using a built-in piezoelectric mirror, spatial interference fringes in the interferometer are successfully obtained. Then, the optimized ratio of the Raman laser's angles is derived, the coefficients of the piezoelectric mirror are self-calibrated in orbit, and various systemic effects are corrected. We achieve a rotation measurement resolution of 50*10^-6 rad/s for a single shot and 17*10^-6 rad/s for an average number of 32. The measured rotation is (-1142+/-29)*10^-6 rad/s and is compatible with that recorded by the classical gyroscope of the CSS. This study paves the way for developing high-precision cold atom gyroscopes in space.
High-precision gyroscopes in space are essential for fundamental physics research and navigation. Due to its potential high precision, the cold atom gyroscope is expected to be one of the next generation of gyroscopes in space. Here, we report the first realization of a cold atom gyroscope, which was demonstrated by the atom interferometer installed in the China Space Station (CSS) as a payload. By compensating for the CSS's high dynamic rotation rate using a built-in piezoelectric mirror, spatial interference fringes in the interferometer are successfully obtained. Then, the optimized ratio of the Raman laser's angles is derived, the coefficients of the piezoelectric mirror are self-calibrated in orbit, and various systemic effects are corrected. We achieve a rotation measurement resolution of 50 μrad/s for a single shot and 17 μrad/s for an average number of 32. The measured rotation is -1142 ± 29 μrad/s and is compatible with that recorded by the classical gyroscope of the CSS. This study paves the way for developing high-precision cold atom gyroscopes in space.
Inertial sensors based on cold atom interferometry exhibit many interesting features for applications related to inertial navigation, particularly in terms of sensitivity and long-term stability. However, at present the typical atom interferometer is still very much an experiment—consisting of a bulky, static apparatus with a limited dynamic range and high sensitivity to environmental effects. To be compliant with mobile applications further development is needed. In this work, we present a compact and mobile experiment, which we recently used to achieve the first inertial measurements with an atomic accelerometer onboard an aircraft. By integrating classical inertial sensors into our apparatus, we are able to operate the atomic sensor well beyond its standard operating range, corresponding to half of an interference fringe. We report atom-based acceleration measurements along both the horizontal and vertical axes of the aircraft with one-shot sensitivities of 2.3 × 10−4 g over a range of ∼ 0.1 g. The same technology can be used to develop cold-atom gyroscopes, which could surpass the best optical gyroscopes in terms of long-term sensitivity. Our apparatus was also designed to study multi-axis atom interferometry with the goal of realizing a full inertial measurement unit comprised of the three axes of acceleration and rotation. Finally, we present a compact and tunable laser system, which constitutes an essential part of any cold-atom-based sensor. The architecture of the laser is based on phase modulating a single fiber-optic laser diode, and can be tuned over a range of 1 GHz in less than 200 μs.
We demonstrate an atom interferometer that uses a laser-cooled continuous beam of 87Rb atoms having velocities of 10–20 m/s. With spatially separated Raman beams to coherently manipulate the atomic wave packets, Mach–Zehnder interference fringes are observed at an interference distance of 2L = 19 mm. The apparatus operates within a small enclosed area of 0.07 mm2 at a bandwidth of 190 Hz with a deduced sensitivity of 7.8×10−5 rad/s/Hz for rotations. Using a low-velocity continuous atomic source in an atom interferometer enables high sampling rates and bandwidths without sacrificing sensitivity and compactness, which are important for applications in real dynamic environments.
The cold atom interference gyroscope (CAIG) offer substantial potential for rotation measurement due to the high sensitivity and stability. The CAIG with a fountain configuration realized by four-pulse could provide a larger interference-loop area, and enhanced performance. However, this kind of CAIG is usually much larger and higher since it requires a vacuum chamber with sufficient height to achieve a long Raman pulse interval. We demonstrate a four-pulse CAIG based on a miniaturized vacuum chamber that enables portable and transportable rotation rate measurements. The main vacuum chamber is realized by whole glass material. The height of the vacuum unit is 0.7 m, the volume is
8.86×104 cm3, and the mass is 75 kg. Then, we estimated the performance of our portable CAIG in the environment of the underground laboratory and the fifth-floor office building. In the laboratory, the sensitivities of the homemade CAIG is
4.44×10−6rad/s
/(Hz)1/2with an interrogation time of 55 ms and an interference area of 25 mm2. In addition, we measured the angular velocity of the Earth, the relative error is 2.4%. Furthermore, we transported the CAIG to the fifth floor of the office building, which is near the subway. Ultimately, the CAIG achieved a sensitivity of
5.47×10−4rad/s
/(Hz)1/2. Additionally, the theoretical maximum interrogation time achieved by this CAIG is 124 ms corresponding to a sensitivity of
5.62×10−8 /(Hz)1/2. Our new design of the compact CAIG could provide novel insights into the miniaturization of CAIGs, while also pointing out areas for further improvement.
A cold-atom gyroscope as an intrinsic high-precision sensor has, however, one inevitable limitation for its dynamic application lying in the vanishing fringe contrast beyond the rotation-rate limit. Here, we realize the measurement beyond the rotation-rate limit via the tip-tilt mirror compensation technique in a three-pulse cold-atom gyroscope. The contrasts of both fringes at an external rotation rate of ${15}^{\ensuremath{\circ}}$/s or below are fully recovered to about 35%, nearly the same as that in the static condition. We elucidate theoretically that intact rotation information can still be extracted from the phase output even though the mirror completely counteracts its rotation. Before reaching 50% contrast loss, detailed numerical verification shows a two-orders-of-magnitude extension in the dynamic range for the compensated case compared with that without compensation. Further analysis shows that no reduction of sensitivity up to ${60}^{\ensuremath{\circ}}$/s is found for our scheme, whereas other schemes have a trade-off between sensitivity and dynamic range. Whereas other schemes have a trade-off between sensitivity and dynamic range, the simulation shows that no reduction to the sensitivity is found for the measurement beyond the rotation-rate limit in our scheme for up to ${60}^{\ensuremath{\circ}}$/s. These features are especially of major relevance in applications such as inertial sensing and navigation.