A similar model was used in the Hafele-Keating experiment to test special relativity on two planes flying in opposite directions. Miniaturization was key.
Contains a disposable tube with 6g of Caesium. You boil it, so when it runs out, you change the tube, 40k USD. Their tube is made by Agilent Technologies, so a replacement since that opened in 1999, and the original machine is from the 60s.
Detection is done with an electron multiplier.
youtu.be/eOti3kKWX-c?t=1166 They compare it with their 100 dollar GPS disciplined oscillator, since GPS satellites have atomic clocks in them.
Uses the frequency of the hyperfine structure of caesium-133 ground state, i.e spin up vs spin down of its valence electron , to define the second.
International System of Units definition of the second since 1967, because this is what atomic clocks use.
TODO why does this have more energy than the hyperfine split of the hydrogen line given that it is further from the nucleus?
Articles by others on the same topic
An atomic clock uses an atomic transition as a frequency reference for an oscillator; counting its calibrated cycles realizes a time interval. In a passive beam implementation, the chemical atoms are repeatedly prepared, interrogated and detected, while feedback control corrects the continuously running oscillator. The Ramsey separated oscillatory fields experiment explains how internal quantum phase becomes a measurable population signal.
The SI second fixes the unperturbed ground state hyperfine structure transition frequency of caesium-133 to exactly . This is a defining value for the ideal transition, rather than a guarantee that an operating apparatus has no shifts.[ref]
SI base unit: second (s) by Bureau International des Poids et Mesures. SI base unit: second (s), defining paragraph and equivalent duration in periods of the unperturbed caesium-133 ground-state hyperfine transition
An atomic clock is a highly precise timekeeping device that uses the vibrations of atoms to measure time. Unlike traditional clocks that rely on mechanical or quartz oscillations, atomic clocks use the natural frequencies of atoms, typically cesium or rubidium. ### Key Features of Atomic Clocks: 1. **Atomic Transitions**: Atomic clocks work by measuring microwave radiation emitted or absorbed by atoms transitioning between energy levels.