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Ramsey fringes and the atomic clock

  1. Mar 26, 2009 #1

    I'm currently researching into the formation and history of atomic clocks. Quartz and crystal clocks can determine resonance frequency measurements to an order of 10^8, but using Ramsey fringes this can become more accurate. Could someone help me explain why Ramsey fringes are a far more accurate means of determining resonance frequencies of a two level atom, than say a quartz clock? In particular, it would great if an answer aimed towards magnetic dipole theory or atom population was proposed.

    This is my understanding so far, the frequency distribution of atomic resonance depends in the time between the two radiation pulses T.

    df = 1/2dT

    Is by decreasing the time between radiation pulses the only factor that makes Ramsey fringes a more accurate method of measuring resonance frequency?

    Thanks for your time.
  2. jcsd
  3. Mar 26, 2009 #2


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    I don't quite understand your question. I think you are confusing measurement techniques with intrinsic precision here.
    The reason why atomic clocks are so precisce is that they utilize levels with a very well definied frequency splitting. There are various ways of measuring this splitting but in principle it is simply a form of spectroscopy. Quartz oscillators are not bad but their frequencies are nowhere near "sharp" as that from an atomic clock and the frequency varies from device to device, it also drifts with temperature etc (which is why good quartz clocks are ovenized).
    Hence, the fundamental difference in precision is simply due to the fact that atoms are much better oscillators than a quartz clock.

    It is perhaps worth noting that there are new generations of clocks that are much more precise than the Cesium clocks that are currently used to define the world time, these new clocks are based on other atoms or ions that have even sharper level transitions.
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