A Chip-Scale 2-Photon Rubidium Atomic Clock

我们的愿景是提供芯片级双光子Rb光学原子钟、频率基准和低相位噪声振荡器，方法是将使用III-V增益芯片的窄线宽激光器与锁定到集成Rb MEMS单元的氮化硅外部栅相结合，并使用由III-V脉冲锁模激光器驱动的氮化硅微环频率梳下转换为10 GHz输出信号。氮化硅光子集成电路(PIC)平台将用于定时系统所需的所有光子和MEMS真空元件的异质集成。一个类比是哈里森的怀表H4，它获得了1773年的经度奖，因为它的小尺寸减少了海军舰艇上温度和加速度漂移的不确定性。通过与文献和包络计算的比较，我们估计所建议的时钟的性能为100 fs/(Hz^0.5)和1 fs精度，其物理封装尺寸约为40 x 30 x 5 mm。这相当于布莱克特审查对关键国家基础设施的72小时暂停期要求后2 ns的不确定性。对于只有计时误差占主导地位的位置不确定，这将导致位置不确定&lt；1米。我们的目标是推出一款性能与MicroChip MHM-2020有源氢脉泽相当的时钟，但x10,000更小，x250质量更小，x150功率更低。有源氢脉泽在7天的测量时间内比Cs原子钟稳定100倍，在1天内比商用CSAC(芯片级原子钟)的精度高100,000倍。

Our vision is to deliver a chip-scale two-photon Rb optical atomic clock, frequency reference and low phase-noise oscillator by combining narrow linewidth lasers using III-V gain chips with silicon nitride external gratings locked to integrated Rb MEMS cells and down-converted to a 10 GHz output signal using a silicon nitride microring frequency comb driven by a III-V pulsed, mode-locked laser. A silicon nitride photonic integrated circuit (PIC) platform will be used for the heterogeneous integrated of all the photonic and MEMS vacuum components required for the timing systems. An analogy is Harrison's pocket watch, H4, that won the Longitude Prize in 1773 as the small size reduced the uncertainties from temperature and acceleration drifts on navy ships.Through comparison with the literature and back of the envelope calculations we estimate a performance of 100 fs/(Hz^0.5) and 1 fs accuracy for the proposed clock with a physics package of around 40 x 30 x 5 mm in size. This corresponds to an uncertainty of 2 ns after the Blackett review 72 hour hold-over period requirement for critical national infrastructure. For a position uncertainty where only timing errors dominate, this results in a position uncertainty < 1 m. Our aim is for a clock with comparable performance to a Microchip MHM-2020 Active Hydrogen Maser but x10,000 smaller, x250 lower mass and x150 lower power. Active hydrogen masers are 100 times more stable than Cs atomic clocks at measuring times of 7 days and x100,000 more accurate at 1 day than a commercial CSAC (Chip Scale Atomic Clock).