Engineering spin polarization in dissipative bosonic systems is crucial for advancing quantum technologies, especially for applications in quantum metrology and space-based quantum simulations. This work demonstrates precise magnetic moment control in multicomponent Bose gases during evaporative cooling via tailored magnetic fields. By adjusting the magnetic field gradients, null point position, and duration, we selectively tune evaporation rates of magnetic sublevels, achieving targeted spin polarization. Theoretical models, validated by numerical simulations and Stern-Gerlach experiments, reveal how magnetic fields reshape trapping potentials and spin-dependent dissipation. The results establish a dissipative spin-selection mechanism governing polarization evolution in evaporatively cooled Bose gases and provide a framework for engineering spin-polarized quantum states.

Accurate measurement of gravitational acceleration is crucial for many scientific research activities such as gravity matching, geological exploration, gravity mapping, etc. Although the cold atom gravimeter (CAG) has a great advantage in measurement accuracy, the physical characteristics of its measurement process lead to a low output frequency, which cannot obtain enough data in a limited time. To solve this problem, this paper proposes an LSTM-EMA based frequency enhancing method for CAG, which firstly reduces the measurement noise by EMA smoothing algorithm, and secondly realizes the predicted frequency boosting by using LSTM model. Finally, the effect of prediction error is weakened again by the EMA smoothing algorithm. Finally, this paper carries out experimental validation using the measured data of the CAG to verify the algorithm’s feasibility. The result shows that the LSTM-EMA based CAG frequency enhancing method can double the output frequency of a CAG without changing the structure and quantity of the equipment, using only the measurement results of one CAG, and only generates a root-mean-square error of 0.0343 μGal, which reflects the feasibility of the method.

Angular momentum coupling manifests widely in diverse physical systems, underpinning the emergent properties and collective dynamics across different scales. The tidal locking, which originates from the synchronization of rotational and orbital motions, has far-reaching impacts in celestial mechanics, reflecting fundamental processes of angular momentum transfer, energy dissipation, and evolution toward dynamical equilibrium. However, its counterpart in mesoscopic quantum fluids has remained largely unexplored. Here we demonstrate the emergence of quantum tidal locking in Bose-Einstein condensates undergoing central force motion in an anharmonic potential. The condensate follows a well-defined orbital trajectory in a static trap and experiences an effective rotating potential induced by the trap anharmonicity. The sustained geometric squeezing continuously deforms the condensate and drives a self-organized synchronization process, in which the intrinsic rotation gradually locks to the orbital motion. Numerical simulations further reveal the formation of a ring-shaped vortex array over longer timescales, arising from the coherent evolution of the rotating matter wave during the locking dynamics. Our findings establish quantum tidal locking in mesoscopic systems as a robust self-organized mechanism for generating and stabilizing circulating states.

Cold Atom Interferometry Gravimeters (CAIGs) are at the forefront of high-precision gravity sensing. Understanding the fundamental noise sources that limit their performance is crucial for their continued development and application. This paper presents a comprehensive simulation model designed to systematically analyze the impact of intrinsic static noise sources, primarily Quantum Projection Noise (QPN) and laser phase noise, on CAIG performance. The model facilitates a quantitative investigation into how key operational parameters—such as atom number, interferometer contrast, free-evolution time, and laser noise spectral characteristics—affect the gravimeter’s sensitivity and stability, which are characterized using Allan deviation and the Power Spectral Density (PSD) of the measurement error. Simulation results quantify the QPN limit, scaling as N-1/2 (where N is atom number), which for 106 atoms corresponds to a short-term Allan deviation on the order of 5 × 10–10 m/s2/√Hz (value to be filled from simulation). Laser phase noise with a white noise floor above approximately 10–9 rad2/Hz begins to significantly degrade performance beyond the QPN limit for 106 atoms. Furthermore, residual vibration noise, even with idealized compensation assumptions in this static noise focused study, can manifest as distinct spectral peaks in the error PSD, underscoring its pervasive nature. This work provides a robust framework for dissecting noise contributions, identifying performance bottlenecks, and offers quantitative insights to guide the optimization of CAIGs towards their theoretical sensitivity limits in engineered systems.

Shipborne cold atom gravimetry is crucial for geodesy, geophysics, resource exploration and autonomous navigation. Under dynamic conditions, effective reduction of measurement noise is one of the key factors in improving the performance of gravimeter. This study innovatively applied Adaptive Particle Filter (APF) algorithm to shipborne cold atom gravimetry which can effectively reduce measurement noise. This APF algorithm was utilized with offset, contrast of fringe and absolute gravity as its state vectors to observe the output of absolute gravimeter. After filtering the measured atom interference fringes, the optimal estimation of absolute gravity is obtained. This method reduces the dispersion of gravity from 42.1 mGal to 13.6 mGal (T = 5 ms), which is 67.7% less than without algorithm. Meanwhile absolute gravity has almost the same change trend. This result confirms the potential of APF algorithm to for enhancing the performance of absolute shipborne gravimetry.

Significance A gyroscope is a core sensor for measuring the angular velocity of an object's motion. It is designed to calibrate the position, attitude, and heading of navigation systems, with its precision directly determining the reliability of positioning systems. Traditional mechanical gyroscopes, micro-electro-mechanical system (MEMS) gyroscopes, and optical gyroscopes are constrained by factors such as mechanical wear, machining precision, and size, thus limiting their application scenarios and making it difficult to further improve long-term stability. Cold atom and ultracold atom interferometric gyroscopes based on the matter wave Sagnac effect utilize laser cooling technology to reduce atoms to the mu K to nK temperature range, significantly enhancing matter-wave coherence. Their theoretical sensitivity is 1011 times higher than that of optical interferometers, with long-term stability potentially reaching the order of 10-16 rad/s. This provides a new solution to overcoming traditional technological bottlenecks and achieving strategic-grade inertial navigation. Simultaneously, cold atom and ultracold atom interferometric gyroscopes can overcome the limitations of thermal atom gyroscopes, such as shorter atomic coherence time and bulky interferometric setups. While preserving the advantages of matter-wave interferometry, they possess the potential for integration and miniaturization, holding application significance in the fields of national defense and security, space science, and civil positioning. Progress Atom interferometric gyroscopes developed to date can be divided based on atomic source temperature characteristics into thermal atom, cold atom, and ultracold atom interferometric gyroscopes. Current experimental thermal atom interferometric gyroscopes have achieved long-term stability on the order of 10-10 rad/s. However, their short atomic coherence time and large interferometric setups have led to the proposal of various schemes adopting cold atoms as the interference source. Cold atom interferometric gyroscopes are primarily divided into two types based on the atomic source type and manipulation method, including the continuous atomic beam type and pulsed atomic cloud type. The method by employing continuous cold atomic beams preserves the advantage of high bandwidth characteristics of thermal atomic beam interferometric gyroscopes while effectively reducing device size without sacrificing sensitivity (Fig. 3). The pulsed cloud scheme for cold atom interferometric gyroscopes employs discretely launched cold atom clouds, utilizing designed laser pulse sequences to coherently split, reflect, and recombine atomic wave packets, and constructing spatially separated Sagnac interference loops. These devices typically adopt a projectile configuration (Figs. 4 and 5). Depending on the laser pulse sequence adopted during the interference experiment, they can be further divided into three-pulse and four-pulse types. Three-pulse sequence interferometers usually employ two identical, counter propagating atom clouds launched toward each other to form a dual interference loop. Four-pulse sequence interferometers often utilize a single atom cloud launched to form a butterfly shaped interference loop. Compared to atomic beam gyroscopes, they have advantages in the more flexible manipulation of coherent atoms. Ultracold atom interferometric gyroscopes developed from cold atom gyroscopes utilize laser cooling and evaporative cooling techniques to prepare neutral atoms (such as 87Rb) in the nK temperature range, forming Bose-Einstein condensates (BECs). Their unique quantum properties provide key advantages for building high-performance atom interferometric gyroscopes. On the one hand, longer coherence time allows for the design of more complex interference paths such as multi-loop circuits, enabling larger effective Sagnac interference areas within limited physical space. On the other hand, ultracold atoms can be precisely confined and guided by electromagnetic fields (magnetic traps, optical traps), enabling highly controllable, compact interference loop configurations that significantly enhance measurement sensitivity per unit volume (Figs. 6 -10). These schemes demonstrate the unique advantages of cold atom and ultracold atom interferometry in terms of sensitivity, stability, and multi-dimensional sensing, providing new avenues for the further development of inertial navigation technology. Conclusions and Prospects Cold atom and ultracold atom interferometric gyroscopes based on matter-wave interference principles feature significant development potential. Current research has validated the feasibility of various technical approaches and yielded notable results. However, much of the research remains at the laboratory stage, with a gap remaining to achieve theoretical precision limits and engineering applications. Future efforts should be focus on further integrating the advantages of multiple disciplines, improving measurement accuracy and stability, and intensifying research on engineering applications. In the long term, with the maturation of quantum control technology and micronano fabrication processes, practical, miniaturized, and integrated inertial units are expected to emerge. This will promote atomic gyroscopes from the laboratory stage into real applications, redefining the precision limits of inertial navigation.

Cold atom gravimeters are used to measure the absolute value of the gravitational acceleration. To mitigate the influence of seismic noise on the mirror, a vibration correction system is used. A commercial seismometer CMG-3ESPC is employed to measure the mirror vibration. The transfer function between the mirror vibration and the output of the seismometer is regarded as a proportional element with a time delay. The best proportional element and the best time delay are obtained by minimizing the standard deviation of the fitting residuals of the interference fringe α − P with vibration correction. This system not only exhibits excellent environmental adaptability but also eliminates the need for rough estimation of local gravitational acceleration during the vibration correction process. The system was built on the homemade cold atom gravimeter to carry out experiments in the laboratory. Compared with the measurement results without vibration correction, the standard deviation of the gravity measurement results was reduced from 120.5 μ Gal to 4.2 μ Gal, resulting in a significant reduction by a factor of 28.7. Meanwhile, its sensitivity was significantly improved from 330.8 μ Gal Hz − 1 to 18.0 μ Gal Hz − 1 by performing vibration correction. In the future, this system is expected to carry out comprehensive verification experiments in more complex noisy environments.

We demonstrate the use of an auxiliary microwave field to extend the bandwidth sensitivity of Rydberg-atom-based microwave electrometry. Electromagnetically induced transparency (EIT) and Autler-Townes (AT) splitting in Rydberg atom microwave electrometry provide advantageous sensitivity for the resonant detection of microwave (MW) fields because the Stark shift of the target Rydberg state takes the linear form of AT splitting. However, the sensitivity is reduced by several orders of magnitude for detuned MW fields because the Stark shift of the target Rydberg state depends on a weak nonlinear effect. We show that the auxiliary microwave field with appropriate Rabi frequency or detuning could shift the atomic energy levels to bring a particular Rydberg-Rydberg transition of interest for microwave sensing into resonance with the target microwave field. Using the atomic superheterodyne method, we verified the general method that regulates Rydberg energy levels using an auxiliary microwave field. The experimental results of this study confirm that this technique works efficiently for detecting microwave fields detuned by up to 100 MHz from resonance with the field-free Rydberg-Rydberg transition used for sensing. The measurement sensitivity of the detuned target field is increased by a factor of 10 compared with that achieved without the application of the auxiliary dressing field.

全自主导航可在不与外界进行信息交换前提下实现全天候、高抗干扰、高隐蔽性定位、导航和授时.冷原子干涉仪由于其物质波和能够提供绝对测量的特性,具有超高的灵敏度和稳定度潜力,有望打造出惯性导航及重力与重力梯度地图匹配辅助导航一体化的全自主高精度导航系统并应用于长时航程载体.从原子干涉仪的构型出发,综述了近十几年国际上的冷原子传感器相关研究,并对各类技术方案进行分析,为适用于一体化全自主导航的方案选择提供参考.

The ability to manipulate quantum states with robustness is crucial for various quantum applications, including quantum computation, quantum simulation, and quantum precision measurement. While pulsed shortcut techniques have proven effective for controlling bands and orbits in optical lattices, their robustness has not been extensively studied. In this paper, we present an improved shortcut design scheme that retains the advantages of high speed and high fidelity, while ensuring exceptional robustness. We conduct comprehensive experimental verifications to demonstrate the effectiveness of this new robust shortcut and its application in quantum gate design. The proposed scheme is expected to enhance the robustness of optical lattice orbit-based interferometry, quantum gates, and other processes.

原子重力测量实验中,需要通过扫频频率源来实现主从Raman激光的线性啁啾,进而补偿原子在自由下落过程中产生的多普勒频移,实现当地重力加速度g的测量.针对传统扫频频率源体积大、发热量大的问题,通过AD9959数字芯片设计了一款扫频频率源,可用作原子喷泉扫频控制和Raman光锁相环鉴频鉴相本振参考.最终通过实验测得:该扫频信号源的相位噪声为-112 dB@1 kHz,频率稳定度为1.38×10-11@1 s,对原子重力仪灵敏度影响为2.81×10-9 g/Hz1/2,600 s积分时间对原子重力仪实验影响为1.15×10-10 g.该系统具有低噪声、高稳定度的特点,可满足搬运式原子重力仪分辨力10-10 g需求.研究结果为原子重力仪从原理样机向工程化可搬运实验测试仪器发展提供了一定参考.

In this paper, a hybrid algorithm to predict the wavelength drift induced by ambient temperature variation in distributed Bragg reflector semiconductor lasers is proposed. This algorithm combines the global search capability of a genetic algorithm (GA) and the supermapping ability of an extreme learning machine (ELM), which not only avoids the randomness of ELM but also improves its generalization performance. In addition, a tenfold cross-validation method is employed to determine the optimal activation function and the number of hidden layer nodes for ELM to construct the most suitable model. After applying multiple sets of test data, the results demonstrate that GA-ELM can quickly and accurately predict the wavelength drift, with an average rms error of 4.09×10-4nm and average mean absolute percentage error of 0.21 %. This model is expected to combine the temperature and current tuning models for a wavelength in follow-up research to achieve rapid tuning and high stability of a wavelength without additional devices.

U(1) global symmetry to solve the strong CP problem could be a remnant of multi-U(1) symmetries from QCD and hidden strong dynamics. Both Peccei-Quinn U(1) and dynamical U(1) are described uniformly, based on which we classify various mixed two-U(1) models to solve both strong CP and quality problems. We propose a moose diagram method with different fermion assignments to directly read relations between CP phases, which illustrate how the strong CP problem is solved in terms of cancellation between CP phases. In two-axion models, we find that the lightest axion is still the same as a QCD axion in the infrared region, while a one-axion model with Z(2) symmetry enhances the axion mass spectrum. Our discussions can be extended to multiaxion cases.

In this study, a method to design highly uniform magnetic field cylinder coils based on the grey wolf optimizer (GWO) algorithm is proposed. For the first time, this method is applied to the magnetic field design area. In this way, the uniform magnetic field region was expended, and the newly designed coils could be utilized in atomic sensors. Compared with other types of coil, namely the Genetic Algorithm (GA) coils and Lee–Whiting coils, the GWO coils exhibit the highest degree of uniformity. The uniform region of the GWO coils is in the range of [−0.53R, 0.53R] along the z-axis and exhibits a relative uniformity of less than 0.1%, as confirmed by experiments. This indicates that the newly designed coils display a huge superiority in the size of the uniform region, thus being able to provide a more uniform magnetic field. With the aim of enhancing the performance of the magnetic field compensation system of SERF atomic sensors, the proposed method also serves as an effective optimized algorithm to design highly uniform magnetic field coils coupled with magnetic shielding layers.

原子重力仪是测量重力加速度的高精度仪器,振动噪声是原子重力仪灵敏度受限的一个主要因素,故需对振动噪声进行抑制.详细介绍了用于原子重力仪的各个隔振技术,分析了以弹簧和阻尼结构组成的被动隔振、以主动反馈元件作动的主动隔振和通过算法剔除振动噪声影响的补偿隔振技术的原理、特点及应用领域,讨论了隔振技术的发展趋势,为原子重力仪的隔振技术研究提供参考.

基于冷原子干涉原理的绝对重力加速度测量装置具有灵敏度高、可长期测量等优点,在基础物理研究以及资源勘探、惯性导航等领域具有十分重要的意义,是公认的下一代绝对重力仪.本文描述了原子干涉重力测量的原理,总结了硬件系统组成和性能要求,指出了限制测量精度和工程化应用的主要因素,并综述了原子重力仪工程化发展的现状和趋势.

里德堡原子是处于高激发态的原子,其主量子数大、寿命高,具有极化率高、电偶极矩大等特点,对外电场十分敏感.基于热蒸气室中里德堡原子的量子干涉原理(电磁感应透明和Autler-Towns分裂效应)的微波电场精密测量不仅具有远高于传统偶极天线的灵敏度,且具有自校准、对外电场干扰少、测量频率范围大等优点,是下一代电场测量标准.本文综述了里德堡原子的微波电场测量研究,详细介绍了其基本原理和当前研究进展,并讨论了未来发展方向.

As the measurement of multiple parameters in a spin-exchange relaxation-free (SERF) comagnetometer requires a long time and complex experimentation, we present a novel dynamic frequency response-based method for the accurate and rapid measurement of key parameters in a SERF comagnetometer. By testing the dynamic frequency response to a transverse oscillating magnetic field, we can obtain multiple parameters simultaneously and quickly without interrupting the operation of the comagnetometer. This method simultaneously measures the nuclear longitudinal relaxation rate and alkali metal number density within minutes, with uncertainties of less than 20.8% and 14.0%, respectively. The main error sources in the nuclear longitudinal relaxation rate and alkali metal number density are the spin-exchange rate constant and spin-exchange enhancement factor, respectively. In addition, the polarization of alkali metal and noble gas atoms can be obtained during the experimental process, and the fast measurement of these parameters is beneficial for applications requiring simultaneous and in situ measurement of spin ensemble performance.

相干激光的性能对原子干涉仪的测量精度有着重要影响.本文介绍了一种制备相干激光的外差式光学锁相环系统,实现了两台外腔半导体激光器频率和相位的同步,锁相后的激光拍频线宽低于1 Hz,10 MHz积分带宽内的残余相位噪音为0.002 rad2,频偏1 ～100 kHz范围内的相位噪音达到-100 dBc/Hz.并研究了闭环相位噪音对原子干涉仪的影响,在自由演化时间为200 ms、拉曼π脉冲时间为30μs、单次循环时间为1 s条件下,锁相后相位噪音对重力测量灵敏度的贡献为10 μGal/√Hz,完全满足高精度原子干涉仪的使用需求.

原子干涉重力仪是一种测量重力加速度的新型仪器.振动噪声会在很大程度上影响原子干涉重力仪的测量精度.为实现高精度的重力加速度测量,在使用原子干涉重力仪测量重力加速度时,必须对振动噪声进行控制.分析了原子干涉重力仪的隔振需求,阐述了原子干涉重力仪隔振系统的研究进展,介绍了以音圈电机为驱动的隔振方法、以压电陶瓷为驱动的隔振方法、振动补偿法三种应用于原子干涉重力仪的隔振方法,总结每种隔振方法的特点及适用场景,并展望原子干涉重力仪隔振技术未来的发展方向.