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Atomic clock
...
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words: 255
articles: 1
How atomic clock works? answer
by
Ciro Santilli
on
Physics Stack Exchange
.
Video 3.
How an atomic clock works, and its use in the global positioning system (GPS) by
EngineerGuy
(2012)
Source
. Shows how conceptually an atomic clock is based on a
feedback loop
of two
hyperfine structure
states of
caesium
atoms (non-
radioactive
caesium-133
as clarified by the
Wikipedia
page). Like a
quartz clock
, it also relies on the
piezoelectricity
of quartz, but unlike the
quartz clock
, the
quartz
is not shaped like a
tuning fork
, and has a much larger resonating frequency of about 7
MHz
. The feedback is completed by producing
photons
that
resonate
at the right frequency to excite the
caesium
.
Video 4.
Inside the
HP
5061A Cesium Clock by
CuriousMarc
(2020)
Source
.
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.
Video 5.
Quick presentation of the
atomic clock
at the
National Physical Laboratory
(2010)
Source
. Their super accurate setup first does
laser cooling
on the
caesium
atoms.
Table of contents
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Caesium standard
(1967, 3.26 cm)
Atomic clock
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Atomic clock
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