Atomic clocks - the most accurate timekeeping mechanism currently known to man. Radiation, vibration, and... quartz? And interesting mix like something straight out of a Star Trek episode.

1. Teaching
Tuesday #2

2. What is time? (in physics)

3. Pendulum

4. Pendulum

5. 1927: SiO2 - Quartz

6. Resonating
Quartz vibrates at a specific frequency when hit with electricity

7. Piezoelectricity
Producing electricity from pressure and/or heat - mechanical stress

8. Piezoelectricity: applications
● Stove lighter
● Accelerometer
● Energy Harvesting (floor surfaces, smartwear, shoes)
● Watches!

9. Quartz Watch - Reverse Piezoelectric
- Quartz has a specific vibration: 32768Hz -
2^15Hz
- Power of 2 makes it translatable to 1Hz and
thereby seconds, one cycle per second
- New electric current drives seconds hand

10. Quartz Watch - not perfect!
Can lose up to 0.06 Hz due to temperature!
Loses time!

11. Quartz Watch - good enough for most!
Even pacemakers!

12. What about perfection?

13. Nature’s building blocks

14. Atoms
Oscillate precisely
Oscillate fungibly across an element

15. 1967: Caesium 133 isotope
9,192,631,770 oscillations of Cs133
● Low energy Cs vs High energy Cs, separatable by a magnet
● Radiowave at 9B Hz hits atoms
● Auto-adjusting

16. The Atomic Clock

17. Next Gen
Strontium, supercooling, lasers
Less than a second during the age of the universe

18. Open Questions
● Where does the Cesium come from?

19. Open Questions
● Where does the Cesium come from? ¯_(ツ)_/¯

20. Open Questions
● Where does the Cesium come from? ¯_(ツ)_/¯
● Does it run out after a while? Do atomic clocks need to be reloaded with Cs
after they “spend” some?

21. Open Questions
● Where does the Cesium come from? ¯_(ツ)_/¯
● Does it run out after a while? Do atomic clocks need to be reloaded with Cs
after they “spend” some? ¯_(ツ)_/¯

22. Open Questions
● Where does the Cesium come from? ¯_(ツ)_/¯
● Does it run out after a while? Do atomic clocks need to be reloaded with Cs
after they “spend” some? ¯_(ツ)_/¯
● How do *small* chip-size atomic clocks work?

23. Open Questions
● Where does the Cesium come from? ¯_(ツ)_/¯
● Does it run out after a while? Do atomic clocks need to be reloaded with Cs
after they “spend” some? ¯_(ツ)_/¯
● How do *small* chip-size atomic clocks work? ¯_(ツ)_/¯

24. Open Questions
● Where does the Cesium come from? ¯_(ツ)_/¯
● Does it run out after a while? Do atomic clocks need to be reloaded with Cs
after they “spend” some? ¯_(ツ)_/¯
● How do *small* chip-size atomic clocks work? ¯_(ツ)_/¯
● If Cs is used most commonly, why isn’t it the ultimate best? Why not switch all
to Rubidium or Strontium, or Cesium for that matter?

25. Open Questions
● Where does the Cesium come from? ¯_(ツ)_/¯
● Does it run out after a while? Do atomic clocks need to be reloaded with Cs
after they “spend” some? ¯_(ツ)_/¯
● How do *small* chip-size atomic clocks work? ¯_(ツ)_/¯
● If Cs is used most commonly, why isn’t it the ultimate best? Why not switch all
to Rubidium or Strontium, or Cesium for that matter? ¯_(ツ)_/¯

26. Open Questions
● Where does the Cesium come from? ¯_(ツ)_/¯
● Does it run out after a while? Do atomic clocks need to be reloaded with Cs
after they “spend” some? ¯_(ツ)_/¯
● How do *small* chip-size atomic clocks work? ¯_(ツ)_/¯
● If Cs is used most commonly, why isn’t it the ultimate best? Why not switch all
to Rubidium or Strontium, or Cesium for that matter? ¯_(ツ)_/¯
● Does magnetic filtering of different energy states of Cs133 mean that atomic
clocks are susceptible to magnetic interference?

27. Open Questions
● Where does the Cesium come from? ¯_(ツ)_/¯
● Does it run out after a while? Do atomic clocks need to be reloaded with Cs
after they “spend” some? ¯_(ツ)_/¯
● How do *small* chip-size atomic clocks work? ¯_(ツ)_/¯
● If Cs is used most commonly, why isn’t it the ultimate best? Why not switch all
to Rubidium or Strontium, or Cesium for that matter? ¯_(ツ)_/¯
● Does magnetic filtering of different energy states of Cs133 mean that atomic
clocks are susceptible to magnetic interference? ¯_(ツ)_/¯

28. Conclusion
Cool stuff, but still a lot of unexplained sci-fi.