Local Oscillator Induced Instabilities in Trapped Ion Frequency Standards
Local Oscillator Induced Instabilities in Trapped Ion Frequency Standards
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发表时间：
1987-12
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影响因子：
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通讯作者：
G. Dick
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作者：
G. Dick
摘要：捕获离子频率源是一类被动原子频率标准，必须使用辅助频率源来询问原子跃迁。对于诸如铷标准的无源原子源，源的最终长期性能不依赖于该本机振荡器，除了受反馈增益限制的程度。对于被捕获的离子源，这种对本地振荡器相位噪声的抗扰性丧失。与铷源相比，使用顺序测量程序，其中仅在某些时间感测来自本地振荡器的信号。由于本机振荡器仅被周期性地采样，本机振荡器频率的某些短期波动将引起稳定的本机振荡器频率与原子吸收频率之间的差的长期波动。我们已经计算了基准振荡器中的这种相位噪声波动对标准性能的影响，作为本地振荡器的占空比的函数，频率波动显示1/f谱密度，如晶体石英振荡器在长测量时间（1-100秒）中通常显示的那样。
Abstract : The trapped ion frequency source is one of a class of passive atomic frequency standards that necessarily use an ancillary frequency source to interrogate the atomic transition. For passive atomic sources such as Rubidium standards, ultimate long term performance of the source is not dependent on this local oscillator, except to the extent limited by feedback gain. For the trapped ion source this immunity to local oscillator phase noise is lost. In contrast to the Rubidium source, a sequential measurement procedure is used in which the signal from the local oscillator is sensed only some of the time. Since the local oscillator is only periodically sampled, certain short term fluctuations in the local oscillator frequency will give rise to long term fluctuations in the difference between the stabilized local oscillator frequency and that of the atomic absorption. We have performed calculations of the influence of such phase noise fluctuations in the reference oscillator on the performance of the standard as a function of duty cycle for a local oscillator with frequency fluctuations showing a 1/f spectral density, as is typically shown by crystal Quartz oscillators for long measuring times (1-100 seconds).