Questions tagged [atomic-clocks]
Use for atomic clocks - not any other type of clock.
57
questions
1
vote
0
answers
21
views
Allan deviation power expansion
In the 'Hand Book of Frequency Analysis' S3.2, by W.J Riley the frequency stability of an oscillator is expressed as a combination of power-law noises of the form $S(f)\propto f^\alpha$, where $f$ is ...
- 1,776
1
vote
0
answers
23
views
Connection between quantum non demolition measurement and the Heisenberg limit in metrology
Quantum non demolition measurements are those that do not feed back action noise into the measured observable. For discrete systems, this leads to the somewhat trivial case of where the observable (...
- 19
5
votes
1
answer
167
views
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 ...
- 7,384
4
votes
3
answers
1k
views
Defining the second by an alien civilization [closed]
(The above question could be phrased better, so feel free to suggest.)
Like many, I was imprecisely told that the second is 9192631770 oscillations of caesium valence electron (or smth along those ...
- 151
1
vote
3
answers
191
views
How to prove that time slow down on all type of clocks? [duplicate]
I read about time dilation and how to prove time dilation existence with light clock.
But how to prove that time slow down on all other type of clocks (biological, mechanical, digital, electric, ...
- 149
0
votes
1
answer
53
views
Conceptual relations between tick indications of a clock and corresponding tick-response indications of a receiver observing that clock
Descriptions of setups and findings involving clocks can also involve distinct observers (in the following a.k.a. receivers) which (in general) perceived, and possibly then analyze, relevant signals ...
- 4,218
2
votes
1
answer
122
views
How to determine whether an atomic clock had "ticked at the Moon's natural pace"? (Nature 614, 13-14 (2023))
The recent news article "What time is it on the Moon? Researchers plan to build a lunar clock", Nature 614, 13-14 (2023) claims that
"Clocks on Earth and the Moon naturally tick at ...
- 4,218
8
votes
1
answer
152
views
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 ...
- 378
10
votes
4
answers
3k
views
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 ...
- 409
2
votes
1
answer
421
views
Why do atomic clocks occasionally fail?
Atomic clocks like the NIST-F1 are extremely accurate yet they can lose a second in a time frame of several million years. Why aren't atomic clocks 100% accurate?
- 49
4
votes
1
answer
162
views
Why H/Cs/I atomic clocks are more complicated than Rb?
It is known that low-cost commercial Rb atomic clocks are fairly simple in construction: gas cell is probed by a light source and excited by RF around 6.8Ghz. When frequency is right - we see decrease ...
- 2,359
1
vote
0
answers
176
views
Solution of Two-Level Atom Equation
I am reading Foot's book. It has the following equations for a two-level atom interacting with light.
$$\begin{align}
i\dot{c}_1&=c_2e^{i(\omega-\omega_0)t}\frac{\Omega}{2}, \\
i\dot{c}_2&...
- 880
0
votes
0
answers
53
views
Measuring time dilation (due to velocity) with an atomic clock
Let there be a system in uniform motion to us at 36,000 mph, and let it have a clock onboard sending us signals as it ticks. Let us have our own clock, and let us account for variations due to that ...
- 1
11
votes
3
answers
867
views
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 ...
- 163
0
votes
1
answer
95
views
Evolution operator of a two-level system in atomic clocks
I have a few questions concerning equation (6) from this (http://arxiv.org/abs/1610.02537) paper from Weinberg in which he describes the time evolution of a two level system e.g. a Cs atom in an ...
1
vote
1
answer
104
views
Frequencies (ticking rates) of the two ${}^{87}\text{Sr}$ clocks in the experiments at the Tokyo Skytree broadcasting tower
In 2019, researches in Japan (M. Takamoto, H. Katori et al.) carried out experiments comparing two transportable ${}^{87}\text{Sr}$ clocks, one ("clock $\mathsf 1$") placed at the ground ...
- 4,218
3
votes
1
answer
64
views
What is a "cycle time" in Allan deviation formula for atomic clock instability? And why does having more independent atoms reduce $\sigma_y(\tau)$?
The usual formula for clock instability is given as
$\sigma_y(\tau)\approx\frac{\Delta f}{f_0\sqrt{N}}\sqrt{\frac{T_c}{\tau}}$
First off what do each of these symbols really mean?
What is $T_c$? The ...
1
vote
2
answers
243
views
Is the accuracy of atomic clocks about engineering limits?
I read that a microwave with specific wavelength is shone on a bunch of atom to make them change energy state from ground to excited state, then they measure this difference in energy to determine its ...
- 11.7k
27
votes
19
answers
12k
views
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 ...
- 437
-2
votes
1
answer
100
views
Do perfectly periodic motions (perfect clocks) exist in nature?
Periodic motions are used in clocks to measure time quantitatively. If we position a pendulum next to process, we can measure how long the process lasted. If the pendulum executed 3.78 periods it took ...
5
votes
2
answers
125
views
Why do the cesium atoms in an atomic clock have to be tossed into the air like a fountain?
Even the NIST website for the standard F-1 clock and the new F-2 do not explain, exactly, why it helps (or is necessary) to make the cesium atoms appear, at least temporarily, weightless....
Wouldn't ...
- 4,269
1
vote
1
answer
108
views
Could trapped ion quantum computers be used as (useful) atomic clocks?
Building a trapped ion quantum computer requires optimizing for different things than a cold atomic clock system. However, a lot of money is currently being dumped into rapidly developing this quantum ...
- 2,879
2
votes
2
answers
462
views
Is a second now defined using 9,192,631,770 Hz or 9,192,631,770.2 Hz of a caesium atom?
This is obviously splitting hairs, to an extent, but I am genuinely curious... And it does make a difference...
In several places, I have seen that .2 added on to the figure...
Did the length of a ...
- 4,269
0
votes
1
answer
225
views
Does special relativity's kinematic time dilation have a physical effect on matter, and how can you test this? [duplicate]
Kinematic time dilation or else named constant velocity time dilation is an apparent time dilation effect but with real consequences on how we measure time and our everyday life like the GPS ...
- 3,768
6
votes
3
answers
1k
views
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 ...
- 69
1
vote
2
answers
256
views
Least count of cesium clock and maximum possible significant figures for time
We know that a second is defined as being equal to the time duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the fundamental ...
- 575
1
vote
2
answers
122
views
How robust is the international atomic time standard against malicious actors?
This answer explains the international atomic time standard (TAI). The fact that the Russian GLONASS and American GPS systems are referenced to their national clock systems, which are then ultimately ...
- 1,286
78
votes
4
answers
7k
views
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 ...
- 937
1
vote
1
answer
95
views
Can we provide a universal clock with atomic clock?
If we use normal clocks then due to the relativiy there will be misleading time, but what will happen with certain atomic clocks with less mistake and relative? If we can measure the time, what ...
- 65
1
vote
1
answer
80
views
How does one get ticks of a clock from an atomic clock's microwave signal?
I understand that in an atomic clock there is a microwave signal that is locked to the frequency of the atomic rotation. However, if one wants to extract time ticks from the microwave signal:
$v(t) =...
- 23
-1
votes
2
answers
393
views
What is the experimental evidence for gravitational time dilation?
There are many experiments done to prove time can be changed. I don't know lots of them, but I think the most popular (most cited) is to put a clock on a fast moving object (airplane), fly around and ...
- 191
6
votes
1
answer
333
views
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 ...
- 73
-1
votes
2
answers
256
views
Clocks only measure repetitions and not time [closed]
To measure time, we use clocks. From sophisticated atomic clocks to everyday wall clocks. When we measure the length of a time interval using a clock, we are really measuring the number of times the ...
- 123
4
votes
3
answers
802
views
How atomic clock works?
I came across to atomic clocks when I was learning special theory of relativity in part Time dilation i simply want know how atomic clock defer from normal clocks.
user207917
1
vote
0
answers
28
views
Atom in Radiation Reservoir (Cohen-Tannoudji formalism)
My task is to generalize the description in Cohen-Tannoudji's "Atom-Photon Interaction", p.284 from dipole only case onto forbidden transitions getting analogues of E.11 and E.13.
Attempt:
Took ...
- 1,177
6
votes
1
answer
423
views
The term "Coherence" is overloaded!
I have troubles with modern terminology in the field of quantum information technologies. There are a lot of new terms that everyone is using and no-one takes time to explain, even though modern ...
- 1,177
0
votes
1
answer
100
views
Atomic clock in expanding space
I have read these questions:
Is there any paper analyzing the validity of Relativity in expanding space?
The Great Atomic Clock of Kansas
photons in expanding space: how is energy conserved?
Is an ...
- 27.9k
0
votes
1
answer
281
views
Atomic spectroscopy with nuclear spin: hyperfine splitting
In $^{171} Yb$, nuclear spin $1/2$, there is a transition:
$^{2}S_{1/2}(F=0) \rightarrow\; ^{2} F_{7/2} (F=3)$
In this paper on p.3 (top-left) they say that $m_F^{(f)} = 0$ at the final state $^2 F_{...
- 1,177
0
votes
2
answers
86
views
Atomic clock in kitchen microwave or other random electronics?
Is it possible for atomic clocks to be put in anything, say a kitchen microwave? Or a regular wall clock?
If so, why are they not in all clocks?
Is it cost? How much does this tech cost to add to ...
-1
votes
1
answer
52
views
How to describe time dependence piece of a stationary state with average phase
I am reading this paper on the synchronization of atomic clocks via entanglement (https://arxiv.org/pdf/quant-ph/0004105.pdf) and can't figure out how they are using $\Omega = (E_{1} - E_{o})/\hbar$ ...
- 1
0
votes
1
answer
414
views
Ramsey spectroscopy of atoms -- Heisenberg Picture
I was reading this thesis on the Ramsey spectroscopy, which deals with Ramsey spectroscopy of a two level system using the Heisenberg picture. This topic is dealt with in the Appendix A.1 of the given ...
- 731
2
votes
5
answers
3k
views
What do clocks measure?
I recently asked a question about the measurement of time, and it has become apparent that I'm really asking a set of related questions, the premises of which need to be shored up and articulated ...
- 2,691
17
votes
2
answers
1k
views
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....
- 3,644
0
votes
0
answers
87
views
Are there transitions of mixed multipolarity in charged ions?
In nuclear physics transitions with mixed multipolarity, ex. (M1+E2), play an important role due to d-wave admixture. I was wondering if analogous situation has ever been considered in atomic ...
- 1,177
5
votes
1
answer
1k
views
How many caesium clocks are there on each GPS satellite ? Is there any other atomic clock on-board?
I am trying to find how many caesium atomic clocks are carried by each of the GPS satellites. And whether the satellites also carry other atomic clocks, such as rubidium or hydrogen clocks.
- 51
2
votes
4
answers
3k
views
Is an atomic clock itself affected by gravity?
Sometimes I read that only time flows at different rates in different conditions when atomic clocks shows a different time compared to atomic clocks at altitude. But sometimes I read that an atomic ...
- 3,282
38
votes
4
answers
7k
views
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....
- 521
4
votes
1
answer
509
views
What is exactly the difference between an active and passive frequency standard?
In the case of passive atomic frequency standard, we take an atomic reference which has a resonant frequency response centered at certain particular frequency. Then we take a local oscillator and tune ...
- 75
0
votes
2
answers
86
views
Where is the periodic nature in the Cs atomic clock? [closed]
In case of pendulum clock,lets say one swing ticks one second..but what is the analogy in case of CAESIUM atomic clock? Is 9,192,631,770 ticks is equivalent to one tick in pendulum clock? And how we ...
1
vote
1
answer
113
views
Timekeeping , optical clocks, and precision
I am having trouble understanding something:
The concept of time measurement.
So I want to simply this as much as possible to get an intuitive understanding:
We define the second by the time it ...
- 777