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Questions tagged [atomic-clocks]

Use for atomic clocks - not any other type of clock.

Atomic clocks are the most accurate time and frequency standards known. They are used as the primary standards for international time distribution services, to control the wave frequency of television broadcasts, and in systems like GPS.

An atomic clock uses an electronic transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its time-keeping element.

There is more information about atomic clocks here.

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What reference clock is an atomic clock measured against?

I looked at a few of the other posts regarding the accuracy of atomic clocks, but I was not able to derive the answer to my question myself. I've seen it stated that atomic clocks are accurate on the order of $10^{-16}$ seconds per second. However,…
zrbecker
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Why do atomic clocks only use caesium?

Modern atomic clocks only use caesium atoms as oscillators. Why don't we use other atoms for this role?
Pinki
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Are today's chip scale atomic clocks accurate enough to conduct my own test of time dilation?

Regarding the Symmetricom SA.45s Quantum™ Chip Scale Atomic Clock, is it accurate enough to test time dilation if I place one at sea level, and one on a mountain? It's accurate to 3.0⋅10−10 per month.
Steve
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Why should a clock be "accurate"?

Having read that atomic clocks are more accurate than mechanical clocks as they lose a second only in millions of years, I wonder why it is necessary for a reference clock to worry about this, if the definition of the second itself is a function of…
androidguy
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Clock uncertainty / building a better clock

Let's say, hypothetically, I've built the best (lowest uncertainty) clock in the world. How is this proven? We can bring my new clock in the next room to a caesium fountain, optical lattice, whatever, and they will drift apart, as all clocks do.…
PhilR
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What makes the thorium-229 nuclear transition special?

Thorium-229 has a famous isomer with an excitation energy of only about 7.8 eV. As I gather from the wikipedia page, this transition was discovered essentially by accident from gamma ray spectroscopy. It's gotten clock gurus all excited recently…
Yly
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Why Rubidium-87 instead of Rubidium-85 for Atomic Clocks?

The traditional Rubidium isotope of choice for atomic clocks is Rubidium-87, although I have found papers describing clocks built around Rubidium-85. I cannot readily find any references for why 87 is preferred in clocks. Rubidium-85 is the…
LetterSized
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How do we know that the cesium-beam frequency used in atomic clocks is always the same?

Atomic clocks use cesium-beam frequency to determine the length of a second. This has shown that the period of orbit of the earth is decreasing. But what experiment showed that cesium-beam's period was so terribly consistent? Did they just run…
futurebird
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If we had just invented the first clock, and we only had a calendar system, how would we set the time of day for the first time?

I've noticed there are extensive answers on this website about the accuracy of atomic clocks and how they reference the time between each other with the average of time between each other, but I realized: that doesn't answer the question of:…
j riv
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Why do atomic clocks measure different elapsed times at different gravitational field strengths if their internal rate is stable quantum transitions

Atomic clocks rely on quantum transitions governed by fundamental constants which do not change with (are independent of) gravity. Does this suggest that their internal ticking rate should remain stable regardless of location despite what we observe…
Navel-gazer
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What's the smallest height difference over which gravitational time dilation has been experimentally observed?

In a famous experiment, reported in Optical Clocks and Relativity. CW Chou, DB Hume, T Rosenband and DJ Wineland. Science 329 no. 5999 pp. 1630-1633 (2010); NIST eprint. and nicely described in this press release, the NIST ion-traps group built…
Emilio Pisanty
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Why does a transition between 2 $s$-orbitals work for cesium's clock transition?

I have a small question about the cesium's clock transition. According to the information on the Wiki: https://en.wikipedia.org/wiki/Caesium_standard, the chosen transitions are two hyperfine ground state, F=3 and F=4. Their orbital angular…
Hsu Bill
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What is stopping optical clocks from redefining the second?

Optical clocks, based on optical transitions either in cold atomic lattices or trapped ions, have been shown to up to one million times better accuracy/precision compared to the cesium microwave atomic clock ($10^{-21}$ frequency stability for…
KF Gauss
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Why the need for more sophisticated atomic clocks?

Why is there such a huge effort in building more sophisticated atomic clocks when the current ones achieve $1$ second of error every few hundred million years? Some achieve frequency stability close to $3\cdot 10^{-13}\tau^{−1/2}$, where $\tau$ is…
Robin
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What is the advantage of a cesium atomic clock over a hydrogen maser as a frequency standard?

Even though both of them are frequency standard, and both are used simultaneously in almost every apex meteorology institute to keep the time, the cesium atomic clocks are more used in this field what is the advantage of cesium atomic clock over the…
Sharun Shaji
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