一种高信噪比铷原子频标物理系统

物理系统是铷原子频标的核心部件,通过分析物理系统原子鉴频信号信噪比对频标频率稳定度的影响机理,对物理系统内部结构进行了改进。改进后的物理系统采用了优化的开槽管微波腔,用Xe气作为起辉气体的铷光谱灯,采用分离滤光的三泡设计方案。对改进后的系统进行了初步测试,秒稳定度约为8×10^-13。此结果表明铷原子频标的稳定度可以突破1×10^-12/τ^(1/2),铷原子频标的长期稳定度还有进一步提高的潜力。     

铷原子频标物理系统小型化设计

介绍了一种用于铷原子频标的小型化物理系统。该物理系统采用了开槽管式微波腔和分离滤光设计方案,体积为30 cm³。对该物理系统进行了初步测试,短期频率稳定度为3.8×10^-12/τ^1/2,表明该物理系统同时具备了小型化和高信噪比特点,可以应用于高性能小型化铷原子频标。     

基于FPGA的北斗驯服铷原子频标装置的研制

为了提高铷原子钟频率的准确度和稳定度,设计了基于FPGA技术的多路输出北斗驯服铷原子频标装置。装置采用粗测和细测的时间间隔测量方法实现铷原子频率的驯服和时间跟踪与同步。采用模块化设计和编程,提高了装置的通用性和可移植性。以铯原子钟时间频率为参照,利用该装置对铷原子钟驯服前后的数据进行多次比对测试,结果表明其频率的相对准确度达到了1.5×10^-13,相对稳定度达到6.97×10^-13,与驯服之前相比,铷原子钟频率的准确度和稳定度均得到大幅提高和改善。     

用于气泡型铷频标的新型环极式微波腔

设计出一种用于气泡铷原子频标的新型环极式感容结构微波腔,它具有结构简单、加工方便、微波场模式优越、腔频易调等优点.用该微波腔研制的铷频标具有很高的信噪比,短期频率稳定度达到2.2×10-12/τ,此结果表明该微波腔可用于制作高性能铷原子频标.     

应用于相干布居囚禁原子钟的低相位噪声微波频率综合器

相干布居囚禁(CPT)原子钟作为微波原子钟的一种类型,由于不需要微波谐振腔即可实现微波探询,可极大降低体积和功耗,从而实现芯片级、低功耗的原子钟。CPT原子钟性能指标的主要限制因素之一是微波综合器的相位噪声,为了提升CPT原子钟的性能,研制了一种应用于CPT原子钟的低相位噪声频率综合器。实验结果表明,频率综合器在200Hz处的绝对相位噪声为108dBc/Hz。微波综合器由于Dick效应对原子钟频率稳定度的限制为8.2×10^-14,可以完全满足CPT原子钟的性能指标要求。此频率综合器也可更广泛地用于其它高性能微波原子精密测量系统以及计量标准器。     

铷原子钟技术对于汞离子钟研制的借鉴性分析

谱灯光抽运被动型铷原子钟具有长寿命、极低的随机频率漂移噪声和较好的短、中期稳定度等显著的优点,在卫星导航定位系统中有着广泛的应用。但是这种铷原子钟的准确度和长期稳定度较差,已经不能满足新一代导航定位系统的要求。离子阱汞离子微波(Hg~+)钟已经达到了主动型氢原子钟的性能指标,与传统铷原子钟相比,具有更加广泛的应用前景。铷原子钟和汞离子微波钟有许多相同点和不同点,对两者差异性进行分析可以借鉴现有铷原子钟的研究,加深对汞离子微波钟工作过程的认识。本文对两者的原理和关键技术进行了比较分析,对汞离子微波钟的发展具有一定的借鉴作用。     

铷原子频标小型磁控管微波谐振腔一体化研究

微波谐振腔是铷原子频标的关键部件,决定着铷原子频标物理部分的鉴频特性。为提高铷原子频标微波谐振腔频率控制精度及实现其小型化,在理论分析和微波谐振腔的仿真分析基础上,开展了TE_(011)模式的小型磁控管微波谐振腔一体化研究,并对设计的磁控管微波谐振腔进行了测试,结果表明采用该小型一体化的磁控管微波谐振腔,铷原子频标频率稳定度得到明显改善,稳定度指标为7.83×10~(-13)(1 s)、1.97×10~(-14)(1 000 s)。     

小型化铷原子频标数字锁频环路设计与实现

设计并实现了一种用于铷原子频标的小型化锁频环路。采用数字锁相倍频技术,实现了10MHz信号的45.5645833次倍频。再经过一级15次倍频后获得频率为6834.6875MHz的铷原子频标微波探寻信号。通过数字电路技术实现了455.645833MHz信号的小调频。测量并分析了455.645833MHz信号的相位噪声,结果表明电路系统对铷频标频率稳定度的贡献为3.2×10^-12τ^-1/2。测量了利用该电路得到的铷频标的短期频率稳定度,结果为5×10^-12τ^-1/2（1s≤τ≤100s）,明显高于一般商品小型化铷原子频标。     

铷原子频标温度系数补偿技术研究

铷原子频标输出频率随工作环境温度变化而改变,影响其频率稳定度指标.为了降低铷原子频标的温度系数,设计了一种基于铷原子基态超精细能级跃迁的微波激励频率补偿电路.该电路在保证铷原子频标相位噪声和短期频率稳定度不受影响的条件下,具有良好的温度系数补偿效果,对于进一步提高铷原子频标的技术指标具有积极的作用.     

BDS-3卫星与其他GNSS系统卫星原子钟性能分析

星载原子钟是决定星上时间基准的基础。利用一年的事后精密钟差数据,对北斗三号(BDS-3)和其他全球卫星导航系统的准确度、漂移率和稳定度进行了分析,以评估全球卫星导航系统(GNSS)在轨原子钟性能。结果表明：BDS-3的铷原子钟准确度在2.62×10^-13～2.54×10^-11之间,氢原子钟在1.64×10^-14～6.77×10^-11之间;BDS-3氢原子钟的漂移率显著优于铷原子钟;BDS-3多数氢原子钟的稳定度可达到10^-15量级。BDS-3的稳定度表现最好,其次是全球定位系统(GPS)、北斗二号(BDS-2)、伽利略(Galileo)和格洛纳斯系统(GLONASS)。     

一种小型化铷原子频标腔泡系统及其频移特性

介绍一种新的小型铷频标腔泡系统的结构特点和频移特性。研究了腔牵引效应、微波功率频移、光频移和缓冲气体温度系数对铷频标输出频率的影响。结果表明,上述因素影响都在可以接受的范围内。此腔泡系统体积小、信噪比高、参数优化方便。利用此腔泡系统可以制成小型化、高性能的铷原子频标。     

Preliminary results of the trapped atom clock on a chip

We present an atomic clock based on the interrogation of magnetically trapped ⁸⁷Rb atoms. Two photons, in the microwave and radiofrequency domain, excite the clock transition. At a magnetic field of 3.23 G the clock transition from |F = 1, m_F = -1? to |F = 2, m_F = 1? is 1st-order insensitive to magnetic field variations. Ramsey interrogation times longer than 2 s can be achieved, leading to a projected clock stability in the low 10^-13 at 1 s for a cloud of 10⁵ atoms. We use an atom chip to cool and trap the atoms. A coplanar waveguide is integrated to the chip to carry the Ramsey interrogation signal, making the physics package as small as (5 cm)³. We describe the experimental setup and show preliminary Ramsey fringes of line width 1.25 Hz.     

A novel method to compensate for the effect of light shift in arubidium atomic clock pumped by a semiconductor laser

Precise measurement of the shift (i.e. microwave frequency shift induced by the electric field of the pumping light) in a rubidium atomic clock pumped by a semiconductor laser is discussed. The spectral lineshape of the microwave resonance, which is used as a frequency discriminator for the atomic clock in the optical microwave double resonance experiment, depends strongly on the spatial distribution of the laser beam intensity, laser frequency detuning, and modulation parameters of the microwave frequency. Based on measurements of the deformation of the resonance lineshape, a self-tuning system was built to compensate for the effect of light shift. As a result of controlling the laser frequency with this system, long-term drift of the microwave frequency as low as 6.3×10^-13/h was obtained     

基于光纤双向时间传递实时驯服铷钟的远程时间溯源

为了提高铷原子钟的远程时间溯源性能,在中国计量科学研究院TWOTFT链路的基础上,实施了对铷原子钟的高精密准实时驯服实验,驯服间隔分别为16,5,1 min,实现了基于TWOTFT的远程时间溯源原理验证.实验结果表明:在远程时间溯源中,TWOTFT相比GNSS时间频率传递效果更优,且1 min TWOTFT远程时间溯源...     

HBAR-Based 3.6 GHz oscillator with low power consumption and low phase noise

We have designed and built 2 oscillators at 1.2 and 3.6 GHz based on high-overtone bulk acoustic resonators (HBARs) for application in chip-scale atomic clocks (CSACs). The measured phase noise of the 3.6 GHz oscillator is -67 dBc/Hz at 300 Hz offset and -100 dBc/Hz at 10 kHz offset. The Allan deviation of the free-running oscillator is 1.5 × 10^-9 at one second integration time and the power consumption is 3.2 mW. The low phase noise allows the oscillator to be locked to a CSAC physics package without significantly degrading the clock performance.     

Hg+ trapped ion standard with the superconducting cavitymaser oscillator

The frequency stability of an atomic standard based on ¹⁹⁹ Hg⁺ ions confined in a hybrid RF/DC linear trap is described. The 40.5-GHz clock transition has been measured to be 17 mHz wide, representing a quality factor greater than 2×10¹². A 160-mHz line is used to steer the output of a 5-MHz crystal oscillator to obtain a stability of 2×10^-15 for 24000-s averaging times. In a separate measurement, a 37-mHz line is used to steer the output of the superconducting cavity maser oscillator to reach 1×10^-15 stability at 10000 s     

Low-phase-noise frequency synthesizer for the trapped atom clock on a chip

We report on the realization of a 6.834-GHz synthesis chain for the trapped atom clock on a chip (TACC) that is being developed at LNE-SYRTE. The chain is based on the frequency multiplication of a 100-MHz reference signal to obtain a signal at 6.4 GHz. It uses a comb generator based on a monolithic GaAs nonlinear transmission line. This is a novelty in the fabrication of high-stability microwave synthesizers. Measurements give a low flicker phase noise of -85 dBrad²/Hz at 1-Hz offset frequency and a white phase noise floor < -115 dBrad²/Hz. Based on these results, we estimate that the performance of the synthesizer is at least one order of magnitude better than the stability goal of TACC. This ensures that the synthesizer will not be limiting the clock performance.