This page is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
While the accuracy of the chip scale atomic clock is mentioned here, it is not mentioned precisely. The referenced commercially available chip scale atomic clock is off by a second every 634.19583967529 years [Microsemi 1].
This differs substantially from the FOCS 1 clock of Switzerland, which is out by 1 second every 30 millions years .
I suggest that the accuracy of the chip scale atomic clock be listed in either Allan deviation or the time taken for it to be out by a second.
Whole Oats 7:16 am, 1 November 2019 (UTC)
"The most accurate time scales are moderated by precise astronomical measurements and the insertion or removal of leap seconds. " seems to be wrong since TAI is just as accurate as anything else, in fact, you could argue that it's more "accurate" than UTC since you can use a precise TAI time in the future and know how long from now that is. With UTC you can't.
How did they set the first atomic clock? Did they use astronomical measurements or some other source?
-- haavis 12:15, 5 Nov 2004 (UTC)
A: Using astronomical measurements. Does the last paragraph in caesium standard explain it well enough?
--tdunc 8:29,10 May 2007
"When the electrons are attracted back closer by the opposite charge of the nucleus, the electrons wiggle before they settle down in their new location. This moving charge causes the light, which is a wave of alternating electricity and magnetism."
This explaination is unacceptable. The author either needs to elaborate or change it all together, why the electron jumps to a lower level. I have reason to believe it is not because of attraction due to charge (which would be constant), rather the electron emits a photon thus lowering its energy level, which could by coincidence mimick charge attraction but I dont feel its the same concept. If so it needs to work both ways, we cant for instance say a repeling charge is responsible for an electron going into a higher energy level. What is with the word "wiggle" anyway?
There is also a transit delay of approximately 1 ms for every 300 kilometers (186 mi) the receiver is from the transmitter. When operating properly and when correctly synchronized, better brands of radio clocks are normally accurate to the second.
Don't you mean millisecond instead of second ? 1 ms for every 300 kilometers means you must be 300,000 (300 x 1000) kilometers from the source to cause a 1 second delay, since the circumference of the earth is ~40,000 km, this does not make much sense.
How radioactive are small atomic clocks? Is it safe to make handheld devices with them?
atomic clocks are not based on radioactivity or decay but on electromagnetic wave frequencies, and the materials used (such as cesium 133) are stable, otherwise the clock wouldn't work well. 81.206.145.191 21:43, 13 May 2007 (UTC)
Cesium-133 is a stable isotope and is not dangerous in a radioactive sense. Rubidium-85 is also a stable isotope, where as Rubidium-87 is vaguely radioactive, decaying with beta-radiation (electron) with half-life of 4.88E10 years, which isn't directly lively. For all practical uses it is safe. Being alkali metals, they would be seriously bad if in contact with skin or water for that matter. Maybe a small text should state what needs to be said: "atomic clocks does not use radioactivity as a mechanism for measurement of time". It is a common misconception and clearly pointing this fact out should be helpful. Cfmd ( talk) 00:43, 24 January 2011 (UTC)
How are Atomic clocks synchronized across the world, or are they not? Do they have to be in the same place to be synchronized off each other sort of thing? Even then how do they set them with such prescison accuracy? —The preceding unsigned comment was added by 90.192.138.193 ( talk) 21:02, 22 December 2006 (UTC).
they can be synched to each other 1: over a symmetric latency connection (such as radio waves), or 2: by using GPS as a reference. a location can tell how it's time compares to GPS, or a single GPS satellite, say 50 nanoseconds ahead. then another place can use that information. 81.206.145.191 21:43, 13 May 2007 (UTC)
Or you can pop a portable atomic clock with a battery backup on a plane. Jim77742 01:25, 20 June 2007 (UTC)
Using airplanes would be unpractical, because Einstein learned us that clocks run slower the faster their speed and the higher their altitude (or the lesser the gravitational field). See [1] and [2] for explanation and experiment with cesium clocks at moderate altitude. Jaho 00:16, 5 July 2007 (UTC)
An answer to the synchronization issue can be found on http://tycho.usno.navy.mil/twstt.html. Jaho 00:29, 5 July 2007 (UTC)
While the clocks may not need to be synchronized, they are often coordinated to roughly have the same time. Use of GPS, GLONASS and TWSTT for such synchronisation is being used. Caesium beam clocks is then usually allowed to count freely and unsteered and then GPS, GLONASS and TWSTT is used for comparison between clocks not being local to each other. Such comparison forms the base of the EAL, TAI and UTC time as being maintained by BIPM. For clocks with not requirement to be part of the BIPM network, they are usually synchronised once and for all using a GPS receiver and then set alone for itself. Many telecom applications does not require the network clock to even have Time of Day but only to give a very stable 2,048 MHz clock to the network. Cfmd ( talk) 00:50, 24 January 2011 (UTC)
www.nist.gov/public_affairs/releases/mercury_atomic_clock.htm —The preceding unsigned comment was added by 218.102.23.117 ( talk) 14:30, 8 January 2007 (UTC).
"Atomic clocks" for less than $50: This marketing term "atomic clock" refers to a radio controlled device receiving a time signal from one or more transceivers connected to real atomic clocks. Examples at: koolatrononline(dot)stores(dot)yahoo(dot)net/hummer-multi-bank-automatic-clock(dot)html www(dot)ehow(dot)com/how_2099664_buy-atomic-clock(dot)html —Preceding unsigned comment added by 131.130.249.17 ( talk) 09:07, 16 February 2010 (UTC)
Someone should add something to this article about the new ytterbium atomic clocks under development. I don't know a lot about them, and, if no one else does it, may end up doing it myself after I read into it more, but if not, at least a mention should be added. —Preceding unsigned comment added by 99.249.74.84 ( talk) 21:27, 15 December 2010 (UTC)
The following passage from this article:
“The first atomic clock was an ammonia maser device built in 1949 at the U.S. National Bureau of Standards (NBS, now NIST).”
seems to conflict with the passage from the “maser” article:
“Theoretically, the principle of the maser was described by Nikolay Basov and Alexander Prokhorov from Lebedev Institute of Physics at an All-Union Conference on Radio-Spectroscopy held by USSR Academy of Sciences in May 1952. They subsequently published their results in October 1954. Independently, Charles H. Townes, J. P. Gordon, and H. J. Zeiger built the first maser at Columbia University in 1953.”
Some explanation to harmonize the dates in these two passages would be helpful. Psalm 119:105 ( talk) 09:58, 17 January 2011 (UTC)
Atomic clocks can also be used as sensors for gravitational and magnetic fields. See: http://www.wired.com/science/discoveries/news/2007/12/time_nist?currentPage=2 72.221.84.128 ( talk) 14:56, 11 January 2012 (UTC)
The statement that Kelvin proposed a clock based on atomic transitions seems a bit misleading. He proposed using the known distinct spectral frequencies of atoms, but wasn't he about 30 years too early to know about atomic transitions? — Preceding unsigned comment added by 173.206.4.23 ( talk) 03:41, 1 November 2012 (UTC)
I noticed that as well. I thought the sentence went beyond misleading to just wrong. -- Davefoc ( talk) 08:30, 29 April 2015 (UTC)
Found the following undated assessment in comment on this page. -- Kvng ( talk) 19:11, 6 September 2012 (UTC)
A number of places in the article include references such as "accurate to one second". These should actually read "precise to one second". Accuracy refers to the central tendency of a measurement, whereas precision refers to the possible range of deviation. — Preceding unsigned comment added by 108.68.83.101 ( talk) 03:00, 22 October 2013 (UTC)
So, if that's the standard by which new clock technology is measured, why do we hear no more of it? Jim.henderson ( talk) 21:08, 2 January 2015 (UTC)
It is requested that a physics diagram or diagrams be
included in this article to
improve its quality. Specific illustrations, plots or diagrams can be requested at the
Graphic Lab. For more information, refer to discussion on this page and/or the listing at Wikipedia:Requested images. |
The section Physics package realisations needs several diagrams added to improve clarity. RJFJR ( talk) 13:59, 22 October 2015 (UTC)
Hi, nuclear clock redirects here while there is not mention of it within this article. Could someone says few words about it within this article or create another article for this kind of clock? Pamputt ( talk) 16:56, 19 August 2016 (UTC)
@ Francis Flinch: Thanks for checking my edits, when you removed the uncertainties from the frequency table in this edit with the edit comment "according to sources", I don't quite understand.
The uncertainties were all taken from the cited sources. For example, the rubidium uncertainty was taken from the cited source, converted by a simple WP:CALCulation from a relative uncertainty of ±3×10−15 to an absolute uncertainty of 6834682610.904324(20).
Just re-checking in case I made a mistake: 87Sr has a frequency of 429228004229873.4 Hz with a relative uncertainty of ±1×10−15, which is 0.43 Hz, so 429228004229873.4(4) is correct. (Unless you'd prefer 429228004229873.40(43), but I think that's excessive precision.)
And the hydrogen maser citation (available at http://cyber.sci-hub.ac/MTAuMTA4OC8wMDI2LTEzOTQvOS8zLzAwNA==/essen1973.pdf if you'd like to check) already says 1420405751.7662±0.003 Hz.
I thought the uncertainties were an informative contrast to the exact-by-definition caesium value, but I can see how someone could disagree. You might find them unhelpful or distracting for various reasons, but "according to sources" confuses me. Could you clarify? 71.41.210.146 ( talk) 17:02, 5 September 2016 (UTC)
I think the unit "attosecond" is dubious in this passage:
In the future this might lead to redefine the caesium microwave based SI second and other new dissemination techniques to transfer clock signals will be required that can be used in both shorter-range and longer-range (frequency) comparisons between attosecond (sub-1 × 10−17 s) accurate clocks without significantly compromising their performance.
The passage seems to call for a unit of relative precision (10−17 to 1), not a unit of time. Can User:Francis Flinch supply a quote from one of the cited sources to justify this unit? Jc3s5h ( talk) 18:16, 14 November 2016 (UTC)
Hello fellow Wikipedians,
I have just modified 5 external links on Atomic clock. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.
This message was posted before February 2018.
After February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than
regular verification using the archive tool instructions below. Editors
have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the
RfC before doing mass systematic removals. This message is updated dynamically through the template {{
source check}}
(last update: 5 June 2024).
Cheers.— InternetArchiveBot ( Report bug) 12:55, 11 July 2017 (UTC)
The following huge chunk of text is almost entirely unsourced. moved here per WP:PRESERVE. Per WP:BURDEN, do not restore without finding reliable sources, checking the content against them, and citing them
A number of methods exist for using hyperfine atomic transitions. These methods, with their respective benefits and drawbacks, have influenced the development of commercial devices and laboratory standards. By tradition, the hardware that is used to probe the atoms is called the physics package.
The atomic beam standard is a direct extension of the Stern-Gerlach atomic splitting experiment. The atoms of choice are heated in an oven to create gas, which is collimated into a beam. This beam, consisting of a mixture of atoms in two states, passes through a state-selector magnet A, where atoms of the wrong state are separated out from the beam. The remaining beam is exposed to an RF field at or near the transition frequency. The beam then passes through a space containing a static homogeneous magnetic field before it is again exposed to the RF field. The RF field and the C-field coil will flip the state of the atoms, with a probability depending on how close the microwave frequency is to the atomic transition frequency. After the second RF field exposure the atomic beam passes through a second state selector magnet B, where the atoms that did not change state (are still in the state selected by magnet A) are discarded. This way, the number of atoms which survive magnet B is related to the microwaves' ability to match the atomic transition frequency. After the second state selector, a mass-spectrometer using an ionizer detects the rate of atoms being received.
Modern variants of this beam mechanism use optical pumping to transition all atoms to the same state rather than dumping half the atoms. Optical detection using scintillation can also be used.
The most common isotope for beam devices is caesium (133Cs), but rubidium (87Rb) and thallium (205Tl) are examples of others used in early research.
The frequency errors can be made very small for a beam device, or predicted (such as the magnetic field pull of the C-coil) in such a way that a high degree of repeatability and stability can be achieved. This is why an atomic beam can be used as a primary standard.
The atomic gas cell standard builds on a confined reference isotope (often an alkali metal such as rubidium (87Rb)) inside an RF cavity. The atoms are excited to a common state using optical pumping; when the applied RF field is swept over the hyperfine spectrum, the gas will absorb the pumping light, and a photodetector provides the response. The absorption peak steers the fly-wheel oscillator.
A typical rubidium gas-cell uses a rubidium (87Rb) lamp heated to 108-110 °C, and an RF field to excite it to produce light, where the D1 and D2 lines are the significant wavelengths. An 85Rb cell filters out the a component of the D1 and D2 line so that only the b component pumps the 87Rb gas cell in the RF cavity.
Among the significant frequency pulling mechanisms inherent to the gas cell are wall-shift, buffer-gas shift, cavity-shift and light-shift. The wall-shift occurs as the gas bumps into the wall of the glass container. Wall-shift can be reduced by wall coating and compensation by buffer gas. The buffer gas shift comes from the reference atoms which bounce into buffer gas atoms such as neon and argon; these shifts can be both positive and negative. The cavity shift comes from the RF cavity, which can deform the resonance amplitude response; this depends upon cavity centre frequency and resonator Q-value. Light-shift is an effect where frequency is pulled differently depending on the light intensity, which often is modulated by the temperature shift of the rubidium lamp and filter cell.
There are thus many factors in which temperature and ageing can shift frequency over time, and this is why a gas cell standard is unfit for a primary standard, but can become a very inexpensive, low-power and small-size solution for a secondary standard or where better stability compared to crystal oscillators is needed, but not the full performance of a caesium beam standard. The rubidium gas standards have seen use in telecommunications systems and portable instruments.
The active maser standard is a development from the atomic beam standard in which the observation time was increased by using a bounce-box. By controlling the beam intensity, spontaneous emission provides sufficient energy to provide a continuous oscillation, which is tapped and used as a reference for a flywheel oscillator.
The active maser is sensitive to wall-shift and cavity pulling. The wall-shift is mitigated by using PTFE coating (or other suitable coating) to reduce the effect. The cavity pulling effect can be reduced by automatic cavity tuning. In addition the magnetic field pulls the frequency.
Although the long-term stability of the active maser is not as good as that of a caesium beam, it remains one of the most stable sources available. The inherent pulling effects make repeatability troublesome and prohibit its use as a primary standard, but it makes an excellent secondary standard. It is used as a low-noise flywheel standard for caesium beam standards.
The fountain standard is a development from the beam standard where the beam is folded back to itself by the Earth's gravity, such that the first and second RF fields are applied during the atoms' upward and downward trips through the same RF cavity, essentially removing phase errors between the two cavities. The slow speed of the atoms also reduces black body temperature shifts. The length of the beam has the same practical limits on vacuum chamber size as a beam clock, but the laser-cooled atoms travel so much slower that the observation time increases about 100-fold (from roughly 10 ms to 1 s [1]) and hence a much higher Q value is achieved in the Ramsey fringes. (The line width is reduced from about 50 Hz to about 1 Hz.)
Caesium fountains have been implemented in many laboratories, but rubidium has even greater ability to provide stability in the fountain configuration.
The ion trap standard is a set of different approaches, but their common property is that a cooled ion is confined in an electrostatic trap. The hyperfine region of the available electron is then being tracked similar to that of a gas cell standard.
Ion traps have been used for numerous ions. 199Hg+ was an early candidate. Quantum logic spectroscopy of a single Al ion became the most precise [2] in 2008. In 2010 an improved setup using a Mg+ logic ion instead of Be was demonstrated [3]
References
Lombardi
was invoked but never defined (see the
help page).-- Jytdog ( talk) 15:40, 28 October 2017 (UTC)
In this edit Francis Flinch asserts "A timing error of 1 nanosecond or one light-nanosecond results in about a 30 cm (11.8 in) positional error." A source source is provided.
The source says in relevant part "one nanosecond equals to about 0.3 m in distance". However, the 1 ns error is about equal to an error of 0.3 m in the distance between the GPS receiver antenna and the GPS satellite. But GPS receivers do not depend on a single satellite; the solution involves at least 4 satellites, and often more. So the actual positional error will depend on a complex combination of the delays in each satellite and receiver.
In addition, the source explains a procedure for correcting for the clock error by observing the satellite with monitoring station(s). Since these corrections are possible, the error will be eliminated or substantially reduced in the final position calculation. Jc3s5h ( talk) 09:30, 15 March 2019 (UTC)
How does an atomic clock work?
Needs more cites to be a B.
Want to help write or improve articles about Time? Join WikiProject Time or visit the Time Portal for a list of articles that need improving. -- Yamara 15:54, 17 January 2008 (UTC)
I don't understand what a hyperfine transition is but I think the article should summarize what a hyperfine transition is because the basis of the second involves the concept.
I also think there should maybe be an explanation of the hyperfine transition in the lead, or leave this technical detail for later in the article. ScientistBuilder ( talk) 22:16, 12 February 2022 (UTC) The page on the hyperfine structure has a bunch of math and is hard to understand. ScientistBuilder ( talk) 22:17, 12 February 2022 (UTC) In trying to understand how atomic clocks work, I went to the page on hyperfine structure, but I don't understand what the fine structure of atom is and what a degenerate state is so I think it would be helpful if someone who has an understanding of this subject helps explain it to ordinary people. ScientistBuilder ( talk) 22:19, 12 February 2022 (UTC) The link to the article on Atomic electron transition does not contain a lot of helpful information to help people understand how atomic clocks work when they click on the link in the lead to understand what is going in the belly of an atomic clock. ScientistBuilder ( talk) 21:20, 13 February 2022 (UTC)
The definition of the caesium-133 at absolute zero according to BIPM in 1997 made me wonder how it is possible to measure the second if absolute zero is not attainable? Absolute zero is not possible because of quantum mechanics but can only be approached asymptotically. ScientistBuilder ( talk) 16:03, 9 February 2022 (UTC)
this phrasing is probably wrong. we talk about "one part in a million", not "one part in a millionth", and it should either be one part in 1*1016, or alternatively, lose the "one part in" preamble.
peace קיפודנחש (aka kipod) ( talk) 16:36, 25 November 2021 (UTC)
Hi, unfortunately I neglected to include a reference. The article discussing construction of "radio" clocks is in a recent EPE magazine and its been covered in "Electronics World" around early 2004. — Preceding unsigned comment added by 88.81.156.140 ( talk • contribs) 07:21, 6 April 2021 (UTC)
In the article, the accuracy of atomic clocks is stated in several places as “expected to neither gain nor lose a second in XXX million/billion years”. I understand that this is only intended to be a more “layman friendly”, or more “intuitive” way to state something like “an accuracy of XXX × 10−16”. However, not only I doubt this way of describing the precision is really more intuitive (since a million years cannot be grasped by the imagination, it's kind of an abstract notion, except for a geologist), I fear it may be plain wrong.
My (limited) understanding is that the Allan deviation of most clocks tends to worsen at very long sample times due to random walk frequency modulation noise and aging effects. Then, it should not be expected for the clocks to achieve their rated accuracy over decades, let alone megayears.
I propose to reword those instances as “expected to neither gain nor lose XXX nanoseconds per month”. I assume a month is, as least as an order of magnitude, a more realistic sample time than XXX megayears. I know the nanosecond is not really an “everyday life” unit. However, in today's highly technological world, it's closer to everyday life than a megayear. At least closer to the life of those reading Wikipedia on an electronic device clocked somewhere in the GHz range.
— Edgar.bonet ( talk) 16:19, 25 February 2016 (UTC)
Hello fellow Wikipedians,
I have just added archive links to 3 external links on
Atomic clock. Please take a moment to review
my edit. If necessary, add {{
cbignore}}
after the link to keep me from modifying it. Alternatively, you can add {{
nobots|deny=InternetArchiveBot}}
to keep me off the page altogether. I made the following changes:
When you have finished reviewing my changes, please set the checked parameter below to true to let others know.
An editor has reviewed this edit and fixed any errors that were found.
Cheers.— cyberbot II Talk to my owner:Online 04:21, 25 February 2016 (UTC)
I tagged the reference to a 1949 NBS atomic clock as 'dubious' and 'citation needed': because I can't find it in the histories. Terry0051 ( talk) 01:10, 25 February 2009 (UTC)
By the way, be sure to look at Louis Essen's own recollections on this history, on the excellent website here: [3]. The section on "Atomic Clock" gives a good history of what was happening in the USA and UK in the 1950s. DonPMitchell ( talk) 16:35, 11 August 2009 (UTC)
i think the article about atomic clocks needs a picture of a HP/Agilent/Symmetricom 5071A, because it is the most common/famous atomic clock (caesium based primary frequency standard) in existence and it has most weight in maintaining UTC - every country's time keeping lab has them. 81.206.145.191 21:43, 13 May 2007 (UTC)
I have a very small travel global Atomic Clock and alarm clock. It is Atomic Radio Controlled. It has to be manually set to: US, UK, Japan and EU via a button on the back. It does not change on its own as I fly from time zone to time zone.
If I am out of range of: England, Switzerland, Japan or the US will the clock no longer sync? In the US the clock wants to sync to Mountain Time due to the Atomic Clock is located in Colorado. Colorado is on Mountain Time.
How does a travel Atomic Clock differ from a stationary clock? My stationary clock updates on its own when it unplugged and plugged in again. If the power goes out the clock resets on its own. A travel clock requires a manual reset, selecting the country for the Atomic Clock and sometimes changing Daylight Savings Time.
Why does the page on Atomic Clocks not cover the small travel version as well? Bree25 ( talk) 02:47, 30 April 2013 (UTC)
"National standards agencies maintain an accuracy of 10-9 seconds per day"
So I set up my brand new atomic clock, go away for 3 million years, and come back to find out it is off by one second. Compared to what? Another atomic clock? I don't see what else it could be if, by definition, an atomic clock is the standard. -- Chauncey27 19:21, 24 December 2005 (UTC)
I am working on improving this article to reach B class status. I am thinking of reorganizing the sections as follows:
I don't think Power Consumption should be a section because it is very small and is not a critical but short role in the article. ScientistBuilder ( talk) 01:28, 15 February 2022 (UTC)
If we try to respond to that long list of suggestions, the thread will splinter into incomprehensible spaghetti. I suggest that you pick whichever section you think is the most egregious and open a new thread. Be patient, these things take time. Constant314 ( talk) 01:43, 16 February 2022 (UTC)
I am wondering if it better to use zeptosecond or 10^-21 seconds or if both are acceptable in the article. I think it is helpful to add the power for reference. Which is best? Use International System of Unit prefixed word, power of 10, both at once, or both are acceptable. ScientistBuilder ( talk) 01:05, 16 February 2022 (UTC)
There has been a bit of dubious content added about chip scale atomic clocks that are attributed to an Article in Wired Magazine. If you look carefully, you will see that the content of the article in not from the staff of Wired, but it is "Partner Content" from SYMMETRICOM. In other words, likely marketing hype. The stuff about IEDs, jamming, drones, and undersea exploration needs a reliable source, and I suspect that those applications do not need atomic clock accuracy. Constant314 ( talk) 03:20, 15 February 2022 (UTC)
Definitely not. I removed this text from the article.
Atomic timekeeping forms the basis of the world's financial system by accurately recording the exact time of financial transactions. [1]
Well, of course, atomic time does underly all time keeping in the modern world. But it required? No. The communications and financial networks are set up to operate plesiosynchronously using quartz time (or worse). What happens when the network operates plesiosynchronously? You get what is called a controlled slip. The world works on 256 bit frames. A controlled slip is the lost or duplication of a frame. In plesiosynchronous operation that occurs about once every six hours. In other words, you get a few bit errors. That is not the only source of bit errors, so the communication and financial networks need some fault tolerance. That can be redundancy to allow the error to be corrected at the receiving end, or it can involve retransmission. But the recovery is built in.
What atomic clocks buy you is that you can spend less man-hours on keeping your clocks synchronized. The old Bell system had one atomic clock and distributed time to the rest of the US and Canada. Each class 1 office synchronized its clock to the master clock. Each class 2 office synced to a class 1 office and so forth down to class 5. As atomic clocks become cheaper, it is economically feasible to push atomic clocks further down into the hierarchy. The whole thing only needed synchronization. The absolute accuracy of the clock was never important. As you push atomic clocks down into the network, it increases resilience. If an office loses it connection to the time source and it has its own already synchronized clock, it can operate plesiosynchronous for a long time without experiencing additional frame slips.
Let's look at what the source says. "Such accurate time is also used to timestamp financial transactions so that we know exactly when trades are happening, which can mean the difference between making a fortune and going broke." That is pretty accurate. Since atomic clock derived time is typically available, the time stamp is typically based on atomic time. Nowhere is it said that atomic time is essential. Nowhere is it implied that the financial system would collapse without atomic time. In fact, I can guarantee that the financial system will keep chugging along on quartz time.
The source also says, "Accurate time is also necessary for synchronizing communications signals so that, for instance, your call isn’t lost as you travel between cellphone towers." Notice that it said, "accurate time" and not "atomic time". Inferring that "accurate time" means "atomic time" is an example of synthesis ( WP:SYN) which leads to an incorrect conclusion. That is why we don't like it. That bit about losing your cell phone call is a bit of grand standing. Good old NIST is keeping you from losing phone calls and going broke. Remember the purpose of the blog. In this case it is PR for NIST. Quartz time will be good enough to not lose cell phone calls.
Constant314 ( talk) 01:26, 16 February 2022 (UTC)
On the subject of whether atomic time is required for financial transactions: the answer is yes. This is an important new application which should be mentioned, the development in recent years of high frequency trading [4] [5] [6] This means large investment firms using microwave links to exploit millisecond price differences in stocks and bonds between exchanges located in different cities, for arbitrage. To avoid conflicts, exchanges have recently gone to UTC timestamp standards for trades [7]. Due to the availability of GPS and NTP sources this may or may not require actual atomic clocks at trading houses, but definitely requires UTC atomic time standards synchronized to milliseconds in financial firms across the world.-- Chetvorno TALK 02:59, 16 February 2022 (UTC)
Because the orders are placed from locations around the world, they frequently arrive at the exchange’s computers out of sequence. The new system allows each computer to time stamp an order when it takes place.
As a result, the trades can be sorted and executed in correct sequence. In a networked marketplace, this precision is necessary not only to prevent illicit trading on advance information known as “front-running,” but also to ensure the fair placement of orders.
References
{{u|
Mark viking}} {
Talk}
05:07, 16 February 2022 (UTC)
How should I remove the section on power consumption? I think it could be merged with a new section on how atomic clocks are built and constructed that makes up the second half of the Mechanism section (see New Section Organization and goal to reach B class status above for explanation). ScientistBuilder ( talk) 02:11, 16 February 2022 (UTC)
Is there an organization similar to NIST or the UK's National Physical Laboratory in the EU? I am looking for other sites that engage in atomic clock research. ScientistBuilder ( talk) 02:04, 16 February 2022 (UTC)
I am working on a way to add information about how atomic clocks are built and constructed. Some material I would put in are:
ScientistBuilder ( talk) 02:20, 16 February 2022 (UTC)
I don't think NASA's project is important enough to the history of atomic clocks to be included in the history section. This is specific to NASA and not representative of the field of atomic clocks overall. This is not an active developed program as far as I can tell and more of an narrowly defined subject. I think it should be moved to the Construction section. In place of the NASA project, I propose a paragraph about optical clocks and ytterbium in the 2000s. ScientistBuilder ( talk) 13:58, 16 February 2022 (UTC)
I think the lead should be organized and rewritten to have no bullet points. Having a list in the lead is not what a good lead has. I propose turning the two bullet points into sentences. ScientistBuilder ( talk) 21:09, 16 February 2022 (UTC)
I think there should be a separate section explaining how clocks lock on to an atomic frequency transition emission. This would include the following:
I'll do a block diagram for a cesium clock, unless someone else has already started on it. Constant314 ( talk) 22:48, 16 February 2022 (UTC)
I am proposing to remove the sentence on Fabry Perot interferometers because there are not that many cases of Fabry Perot interferometers in the literature for atomic clocks on NISt and other websites. I think the main improvements were cooling with lasers and optical combs. ScientistBuilder ( talk) 03:04, 16 February 2022 (UTC)
There are multiple paragraphs in different sections that cover the definition of the second. I want to remove the material in the Time Measurement section and put any material that is there and not in the How Atomic Clocks Work Section in the How Atomic Clocks Work section. ScientistBuilder ( talk) 19:20, 19 February 2022 (UTC)
Atomic clocks with caesium use microwaves to measure time. The atomic clock measures the frequency of the microwaves. The atomic clock sends a microwave to excite the atoms. The microwave is measured and if it not 9192631770Hz, the microwave is corrected. ScientistBuilder ( talk) 14:57, 19 February 2022 (UTC)
The article has too much information about the accuracy of specific clocks. I propose removing all parts that mention a clock that reached a new level of accuracy unless it achieved a world record such as to . The section on accuracy could be simplified. ScientistBuilder ( talk) 21:24, 20 February 2022 (UTC)
the accuracy section does not define . Therefore, I propose removing the use of the term. ScientistBuilder ( talk) 21:25, 20 February 2022 (UTC)
The article on atomic clocks does not need to include a discussion about the differences of UTC and UT1 and Earth's rotation so I am removing UT1. ScientistBuilder ( talk) 22:51, 20 February 2022 (UTC)
I propose changing the lead's first sentence to "An atomic clock is a clock that measures time by monitoring the oscillations of atoms." The current sentence is pretty technical and I think it would be better to start with a more understandable and intuitive sentence and go into how electromagnetic radiation is used later. ScientistBuilder ( talk) 00:54, 21 February 2022 (UTC)
I propose to simplify the sentence at the end of the lead that states atomic clocks deviate by at most a nanosecond every day (about one part in 10^14). This is because the accuracy of an atomic clock is often evaluated by the deviation from the second but not by the deviation from the second over a day. ScientistBuilder ( talk) 21:11, 16 February 2022 (UTC)
There are some good images of atomic clocks from the BIPM at https://www.bipm.org/en/-/2021-12-21-record-tai. I would like to find a way to put them in the article. I have added a graph of the accuracy of atomic clocks. I am uploading the rest to Wikimedia Commons:
I want to add more images of atomic clocks. Adding images of atomic clocks from around the globe contributes to a global perspective and not just NIST.
( talk) 01:49, 18 February 2022 (UTC)
I am proposing the following revision to the first subsection: "James Clerk Maxwell and Lord Kelvin were the first to argue that radiation could be used to keep track of time. The first practical considerations of how an atomic clock might work were made by Isidor Rabi in 1939. He proposed the concept in 1945, which led to a demonstration of a clock based on ammonia in 1949. This led to to the first accurate atomic clock being built at the National Physical Laboratory in the United Kingdom with caesium atoms." ScientistBuilder ( talk) 02:31, 21 February 2022 (UTC)
I am working on improving the section's narrative about the history of time and the tropical year and now caesium clocks. ScientistBuilder ( talk) 02:38, 22 February 2022 (UTC)
ScientistBuilder ( talk) 02:40, 22 February 2022 (UTC)
For some reason a reference to James Clerk Maxwell and Lord Kelvin was removed. I am wondering why a sentence about the first people to propose the atomic clock is too much to include or why it was removed. ScientistBuilder ( talk) 02:45, 22 February 2022 (UTC)
I propose the History section should not include optical clock research and other experimental advances since the 1990s like fountains and ion traps. I think its better to put these later in the article. ScientistBuilder ( talk) 02:59, 21 February 2022 (UTC)
@Chetvorno
The paragraph in the International System of Units Definition includes information that is in the History section. I propose moving the information that is not in the History section there and deleting the rest. ScientistBuilder ( talk) 15:27, 22 February 2022 (UTC)
I am working on improving the article but there is a lot of redundant information about redefining the second, optical clocks and discoveries. I would like to reduce this redundancy by moving and reorganizing the sections. I propose removing the history section because to understand the history, the mechanism should be explained first. ScientistBuilder ( talk) 16:12, 22 February 2022 (UTC)
Femtosecond Combs Section Laser Cooling Section Applications of More accurate clocks Redefining the second This involves subjects such as fiber optic communication of time, GNSS
Cite error: There are <ref group=Microsemi>
tags on this page, but the references will not show without a {{reflist|group=Microsemi}}
template (see the
help page).
This page is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
While the accuracy of the chip scale atomic clock is mentioned here, it is not mentioned precisely. The referenced commercially available chip scale atomic clock is off by a second every 634.19583967529 years [Microsemi 1].
This differs substantially from the FOCS 1 clock of Switzerland, which is out by 1 second every 30 millions years .
I suggest that the accuracy of the chip scale atomic clock be listed in either Allan deviation or the time taken for it to be out by a second.
Whole Oats 7:16 am, 1 November 2019 (UTC)
"The most accurate time scales are moderated by precise astronomical measurements and the insertion or removal of leap seconds. " seems to be wrong since TAI is just as accurate as anything else, in fact, you could argue that it's more "accurate" than UTC since you can use a precise TAI time in the future and know how long from now that is. With UTC you can't.
How did they set the first atomic clock? Did they use astronomical measurements or some other source?
-- haavis 12:15, 5 Nov 2004 (UTC)
A: Using astronomical measurements. Does the last paragraph in caesium standard explain it well enough?
--tdunc 8:29,10 May 2007
"When the electrons are attracted back closer by the opposite charge of the nucleus, the electrons wiggle before they settle down in their new location. This moving charge causes the light, which is a wave of alternating electricity and magnetism."
This explaination is unacceptable. The author either needs to elaborate or change it all together, why the electron jumps to a lower level. I have reason to believe it is not because of attraction due to charge (which would be constant), rather the electron emits a photon thus lowering its energy level, which could by coincidence mimick charge attraction but I dont feel its the same concept. If so it needs to work both ways, we cant for instance say a repeling charge is responsible for an electron going into a higher energy level. What is with the word "wiggle" anyway?
There is also a transit delay of approximately 1 ms for every 300 kilometers (186 mi) the receiver is from the transmitter. When operating properly and when correctly synchronized, better brands of radio clocks are normally accurate to the second.
Don't you mean millisecond instead of second ? 1 ms for every 300 kilometers means you must be 300,000 (300 x 1000) kilometers from the source to cause a 1 second delay, since the circumference of the earth is ~40,000 km, this does not make much sense.
How radioactive are small atomic clocks? Is it safe to make handheld devices with them?
atomic clocks are not based on radioactivity or decay but on electromagnetic wave frequencies, and the materials used (such as cesium 133) are stable, otherwise the clock wouldn't work well. 81.206.145.191 21:43, 13 May 2007 (UTC)
Cesium-133 is a stable isotope and is not dangerous in a radioactive sense. Rubidium-85 is also a stable isotope, where as Rubidium-87 is vaguely radioactive, decaying with beta-radiation (electron) with half-life of 4.88E10 years, which isn't directly lively. For all practical uses it is safe. Being alkali metals, they would be seriously bad if in contact with skin or water for that matter. Maybe a small text should state what needs to be said: "atomic clocks does not use radioactivity as a mechanism for measurement of time". It is a common misconception and clearly pointing this fact out should be helpful. Cfmd ( talk) 00:43, 24 January 2011 (UTC)
How are Atomic clocks synchronized across the world, or are they not? Do they have to be in the same place to be synchronized off each other sort of thing? Even then how do they set them with such prescison accuracy? —The preceding unsigned comment was added by 90.192.138.193 ( talk) 21:02, 22 December 2006 (UTC).
they can be synched to each other 1: over a symmetric latency connection (such as radio waves), or 2: by using GPS as a reference. a location can tell how it's time compares to GPS, or a single GPS satellite, say 50 nanoseconds ahead. then another place can use that information. 81.206.145.191 21:43, 13 May 2007 (UTC)
Or you can pop a portable atomic clock with a battery backup on a plane. Jim77742 01:25, 20 June 2007 (UTC)
Using airplanes would be unpractical, because Einstein learned us that clocks run slower the faster their speed and the higher their altitude (or the lesser the gravitational field). See [1] and [2] for explanation and experiment with cesium clocks at moderate altitude. Jaho 00:16, 5 July 2007 (UTC)
An answer to the synchronization issue can be found on http://tycho.usno.navy.mil/twstt.html. Jaho 00:29, 5 July 2007 (UTC)
While the clocks may not need to be synchronized, they are often coordinated to roughly have the same time. Use of GPS, GLONASS and TWSTT for such synchronisation is being used. Caesium beam clocks is then usually allowed to count freely and unsteered and then GPS, GLONASS and TWSTT is used for comparison between clocks not being local to each other. Such comparison forms the base of the EAL, TAI and UTC time as being maintained by BIPM. For clocks with not requirement to be part of the BIPM network, they are usually synchronised once and for all using a GPS receiver and then set alone for itself. Many telecom applications does not require the network clock to even have Time of Day but only to give a very stable 2,048 MHz clock to the network. Cfmd ( talk) 00:50, 24 January 2011 (UTC)
www.nist.gov/public_affairs/releases/mercury_atomic_clock.htm —The preceding unsigned comment was added by 218.102.23.117 ( talk) 14:30, 8 January 2007 (UTC).
"Atomic clocks" for less than $50: This marketing term "atomic clock" refers to a radio controlled device receiving a time signal from one or more transceivers connected to real atomic clocks. Examples at: koolatrononline(dot)stores(dot)yahoo(dot)net/hummer-multi-bank-automatic-clock(dot)html www(dot)ehow(dot)com/how_2099664_buy-atomic-clock(dot)html —Preceding unsigned comment added by 131.130.249.17 ( talk) 09:07, 16 February 2010 (UTC)
Someone should add something to this article about the new ytterbium atomic clocks under development. I don't know a lot about them, and, if no one else does it, may end up doing it myself after I read into it more, but if not, at least a mention should be added. —Preceding unsigned comment added by 99.249.74.84 ( talk) 21:27, 15 December 2010 (UTC)
The following passage from this article:
“The first atomic clock was an ammonia maser device built in 1949 at the U.S. National Bureau of Standards (NBS, now NIST).”
seems to conflict with the passage from the “maser” article:
“Theoretically, the principle of the maser was described by Nikolay Basov and Alexander Prokhorov from Lebedev Institute of Physics at an All-Union Conference on Radio-Spectroscopy held by USSR Academy of Sciences in May 1952. They subsequently published their results in October 1954. Independently, Charles H. Townes, J. P. Gordon, and H. J. Zeiger built the first maser at Columbia University in 1953.”
Some explanation to harmonize the dates in these two passages would be helpful. Psalm 119:105 ( talk) 09:58, 17 January 2011 (UTC)
Atomic clocks can also be used as sensors for gravitational and magnetic fields. See: http://www.wired.com/science/discoveries/news/2007/12/time_nist?currentPage=2 72.221.84.128 ( talk) 14:56, 11 January 2012 (UTC)
The statement that Kelvin proposed a clock based on atomic transitions seems a bit misleading. He proposed using the known distinct spectral frequencies of atoms, but wasn't he about 30 years too early to know about atomic transitions? — Preceding unsigned comment added by 173.206.4.23 ( talk) 03:41, 1 November 2012 (UTC)
I noticed that as well. I thought the sentence went beyond misleading to just wrong. -- Davefoc ( talk) 08:30, 29 April 2015 (UTC)
Found the following undated assessment in comment on this page. -- Kvng ( talk) 19:11, 6 September 2012 (UTC)
A number of places in the article include references such as "accurate to one second". These should actually read "precise to one second". Accuracy refers to the central tendency of a measurement, whereas precision refers to the possible range of deviation. — Preceding unsigned comment added by 108.68.83.101 ( talk) 03:00, 22 October 2013 (UTC)
So, if that's the standard by which new clock technology is measured, why do we hear no more of it? Jim.henderson ( talk) 21:08, 2 January 2015 (UTC)
It is requested that a physics diagram or diagrams be
included in this article to
improve its quality. Specific illustrations, plots or diagrams can be requested at the
Graphic Lab. For more information, refer to discussion on this page and/or the listing at Wikipedia:Requested images. |
The section Physics package realisations needs several diagrams added to improve clarity. RJFJR ( talk) 13:59, 22 October 2015 (UTC)
Hi, nuclear clock redirects here while there is not mention of it within this article. Could someone says few words about it within this article or create another article for this kind of clock? Pamputt ( talk) 16:56, 19 August 2016 (UTC)
@ Francis Flinch: Thanks for checking my edits, when you removed the uncertainties from the frequency table in this edit with the edit comment "according to sources", I don't quite understand.
The uncertainties were all taken from the cited sources. For example, the rubidium uncertainty was taken from the cited source, converted by a simple WP:CALCulation from a relative uncertainty of ±3×10−15 to an absolute uncertainty of 6834682610.904324(20).
Just re-checking in case I made a mistake: 87Sr has a frequency of 429228004229873.4 Hz with a relative uncertainty of ±1×10−15, which is 0.43 Hz, so 429228004229873.4(4) is correct. (Unless you'd prefer 429228004229873.40(43), but I think that's excessive precision.)
And the hydrogen maser citation (available at http://cyber.sci-hub.ac/MTAuMTA4OC8wMDI2LTEzOTQvOS8zLzAwNA==/essen1973.pdf if you'd like to check) already says 1420405751.7662±0.003 Hz.
I thought the uncertainties were an informative contrast to the exact-by-definition caesium value, but I can see how someone could disagree. You might find them unhelpful or distracting for various reasons, but "according to sources" confuses me. Could you clarify? 71.41.210.146 ( talk) 17:02, 5 September 2016 (UTC)
I think the unit "attosecond" is dubious in this passage:
In the future this might lead to redefine the caesium microwave based SI second and other new dissemination techniques to transfer clock signals will be required that can be used in both shorter-range and longer-range (frequency) comparisons between attosecond (sub-1 × 10−17 s) accurate clocks without significantly compromising their performance.
The passage seems to call for a unit of relative precision (10−17 to 1), not a unit of time. Can User:Francis Flinch supply a quote from one of the cited sources to justify this unit? Jc3s5h ( talk) 18:16, 14 November 2016 (UTC)
Hello fellow Wikipedians,
I have just modified 5 external links on Atomic clock. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.
This message was posted before February 2018.
After February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than
regular verification using the archive tool instructions below. Editors
have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the
RfC before doing mass systematic removals. This message is updated dynamically through the template {{
source check}}
(last update: 5 June 2024).
Cheers.— InternetArchiveBot ( Report bug) 12:55, 11 July 2017 (UTC)
The following huge chunk of text is almost entirely unsourced. moved here per WP:PRESERVE. Per WP:BURDEN, do not restore without finding reliable sources, checking the content against them, and citing them
A number of methods exist for using hyperfine atomic transitions. These methods, with their respective benefits and drawbacks, have influenced the development of commercial devices and laboratory standards. By tradition, the hardware that is used to probe the atoms is called the physics package.
The atomic beam standard is a direct extension of the Stern-Gerlach atomic splitting experiment. The atoms of choice are heated in an oven to create gas, which is collimated into a beam. This beam, consisting of a mixture of atoms in two states, passes through a state-selector magnet A, where atoms of the wrong state are separated out from the beam. The remaining beam is exposed to an RF field at or near the transition frequency. The beam then passes through a space containing a static homogeneous magnetic field before it is again exposed to the RF field. The RF field and the C-field coil will flip the state of the atoms, with a probability depending on how close the microwave frequency is to the atomic transition frequency. After the second RF field exposure the atomic beam passes through a second state selector magnet B, where the atoms that did not change state (are still in the state selected by magnet A) are discarded. This way, the number of atoms which survive magnet B is related to the microwaves' ability to match the atomic transition frequency. After the second state selector, a mass-spectrometer using an ionizer detects the rate of atoms being received.
Modern variants of this beam mechanism use optical pumping to transition all atoms to the same state rather than dumping half the atoms. Optical detection using scintillation can also be used.
The most common isotope for beam devices is caesium (133Cs), but rubidium (87Rb) and thallium (205Tl) are examples of others used in early research.
The frequency errors can be made very small for a beam device, or predicted (such as the magnetic field pull of the C-coil) in such a way that a high degree of repeatability and stability can be achieved. This is why an atomic beam can be used as a primary standard.
The atomic gas cell standard builds on a confined reference isotope (often an alkali metal such as rubidium (87Rb)) inside an RF cavity. The atoms are excited to a common state using optical pumping; when the applied RF field is swept over the hyperfine spectrum, the gas will absorb the pumping light, and a photodetector provides the response. The absorption peak steers the fly-wheel oscillator.
A typical rubidium gas-cell uses a rubidium (87Rb) lamp heated to 108-110 °C, and an RF field to excite it to produce light, where the D1 and D2 lines are the significant wavelengths. An 85Rb cell filters out the a component of the D1 and D2 line so that only the b component pumps the 87Rb gas cell in the RF cavity.
Among the significant frequency pulling mechanisms inherent to the gas cell are wall-shift, buffer-gas shift, cavity-shift and light-shift. The wall-shift occurs as the gas bumps into the wall of the glass container. Wall-shift can be reduced by wall coating and compensation by buffer gas. The buffer gas shift comes from the reference atoms which bounce into buffer gas atoms such as neon and argon; these shifts can be both positive and negative. The cavity shift comes from the RF cavity, which can deform the resonance amplitude response; this depends upon cavity centre frequency and resonator Q-value. Light-shift is an effect where frequency is pulled differently depending on the light intensity, which often is modulated by the temperature shift of the rubidium lamp and filter cell.
There are thus many factors in which temperature and ageing can shift frequency over time, and this is why a gas cell standard is unfit for a primary standard, but can become a very inexpensive, low-power and small-size solution for a secondary standard or where better stability compared to crystal oscillators is needed, but not the full performance of a caesium beam standard. The rubidium gas standards have seen use in telecommunications systems and portable instruments.
The active maser standard is a development from the atomic beam standard in which the observation time was increased by using a bounce-box. By controlling the beam intensity, spontaneous emission provides sufficient energy to provide a continuous oscillation, which is tapped and used as a reference for a flywheel oscillator.
The active maser is sensitive to wall-shift and cavity pulling. The wall-shift is mitigated by using PTFE coating (or other suitable coating) to reduce the effect. The cavity pulling effect can be reduced by automatic cavity tuning. In addition the magnetic field pulls the frequency.
Although the long-term stability of the active maser is not as good as that of a caesium beam, it remains one of the most stable sources available. The inherent pulling effects make repeatability troublesome and prohibit its use as a primary standard, but it makes an excellent secondary standard. It is used as a low-noise flywheel standard for caesium beam standards.
The fountain standard is a development from the beam standard where the beam is folded back to itself by the Earth's gravity, such that the first and second RF fields are applied during the atoms' upward and downward trips through the same RF cavity, essentially removing phase errors between the two cavities. The slow speed of the atoms also reduces black body temperature shifts. The length of the beam has the same practical limits on vacuum chamber size as a beam clock, but the laser-cooled atoms travel so much slower that the observation time increases about 100-fold (from roughly 10 ms to 1 s [1]) and hence a much higher Q value is achieved in the Ramsey fringes. (The line width is reduced from about 50 Hz to about 1 Hz.)
Caesium fountains have been implemented in many laboratories, but rubidium has even greater ability to provide stability in the fountain configuration.
The ion trap standard is a set of different approaches, but their common property is that a cooled ion is confined in an electrostatic trap. The hyperfine region of the available electron is then being tracked similar to that of a gas cell standard.
Ion traps have been used for numerous ions. 199Hg+ was an early candidate. Quantum logic spectroscopy of a single Al ion became the most precise [2] in 2008. In 2010 an improved setup using a Mg+ logic ion instead of Be was demonstrated [3]
References
Lombardi
was invoked but never defined (see the
help page).-- Jytdog ( talk) 15:40, 28 October 2017 (UTC)
In this edit Francis Flinch asserts "A timing error of 1 nanosecond or one light-nanosecond results in about a 30 cm (11.8 in) positional error." A source source is provided.
The source says in relevant part "one nanosecond equals to about 0.3 m in distance". However, the 1 ns error is about equal to an error of 0.3 m in the distance between the GPS receiver antenna and the GPS satellite. But GPS receivers do not depend on a single satellite; the solution involves at least 4 satellites, and often more. So the actual positional error will depend on a complex combination of the delays in each satellite and receiver.
In addition, the source explains a procedure for correcting for the clock error by observing the satellite with monitoring station(s). Since these corrections are possible, the error will be eliminated or substantially reduced in the final position calculation. Jc3s5h ( talk) 09:30, 15 March 2019 (UTC)
How does an atomic clock work?
Needs more cites to be a B.
Want to help write or improve articles about Time? Join WikiProject Time or visit the Time Portal for a list of articles that need improving. -- Yamara 15:54, 17 January 2008 (UTC)
I don't understand what a hyperfine transition is but I think the article should summarize what a hyperfine transition is because the basis of the second involves the concept.
I also think there should maybe be an explanation of the hyperfine transition in the lead, or leave this technical detail for later in the article. ScientistBuilder ( talk) 22:16, 12 February 2022 (UTC) The page on the hyperfine structure has a bunch of math and is hard to understand. ScientistBuilder ( talk) 22:17, 12 February 2022 (UTC) In trying to understand how atomic clocks work, I went to the page on hyperfine structure, but I don't understand what the fine structure of atom is and what a degenerate state is so I think it would be helpful if someone who has an understanding of this subject helps explain it to ordinary people. ScientistBuilder ( talk) 22:19, 12 February 2022 (UTC) The link to the article on Atomic electron transition does not contain a lot of helpful information to help people understand how atomic clocks work when they click on the link in the lead to understand what is going in the belly of an atomic clock. ScientistBuilder ( talk) 21:20, 13 February 2022 (UTC)
The definition of the caesium-133 at absolute zero according to BIPM in 1997 made me wonder how it is possible to measure the second if absolute zero is not attainable? Absolute zero is not possible because of quantum mechanics but can only be approached asymptotically. ScientistBuilder ( talk) 16:03, 9 February 2022 (UTC)
this phrasing is probably wrong. we talk about "one part in a million", not "one part in a millionth", and it should either be one part in 1*1016, or alternatively, lose the "one part in" preamble.
peace קיפודנחש (aka kipod) ( talk) 16:36, 25 November 2021 (UTC)
Hi, unfortunately I neglected to include a reference. The article discussing construction of "radio" clocks is in a recent EPE magazine and its been covered in "Electronics World" around early 2004. — Preceding unsigned comment added by 88.81.156.140 ( talk • contribs) 07:21, 6 April 2021 (UTC)
In the article, the accuracy of atomic clocks is stated in several places as “expected to neither gain nor lose a second in XXX million/billion years”. I understand that this is only intended to be a more “layman friendly”, or more “intuitive” way to state something like “an accuracy of XXX × 10−16”. However, not only I doubt this way of describing the precision is really more intuitive (since a million years cannot be grasped by the imagination, it's kind of an abstract notion, except for a geologist), I fear it may be plain wrong.
My (limited) understanding is that the Allan deviation of most clocks tends to worsen at very long sample times due to random walk frequency modulation noise and aging effects. Then, it should not be expected for the clocks to achieve their rated accuracy over decades, let alone megayears.
I propose to reword those instances as “expected to neither gain nor lose XXX nanoseconds per month”. I assume a month is, as least as an order of magnitude, a more realistic sample time than XXX megayears. I know the nanosecond is not really an “everyday life” unit. However, in today's highly technological world, it's closer to everyday life than a megayear. At least closer to the life of those reading Wikipedia on an electronic device clocked somewhere in the GHz range.
— Edgar.bonet ( talk) 16:19, 25 February 2016 (UTC)
Hello fellow Wikipedians,
I have just added archive links to 3 external links on
Atomic clock. Please take a moment to review
my edit. If necessary, add {{
cbignore}}
after the link to keep me from modifying it. Alternatively, you can add {{
nobots|deny=InternetArchiveBot}}
to keep me off the page altogether. I made the following changes:
When you have finished reviewing my changes, please set the checked parameter below to true to let others know.
An editor has reviewed this edit and fixed any errors that were found.
Cheers.— cyberbot II Talk to my owner:Online 04:21, 25 February 2016 (UTC)
I tagged the reference to a 1949 NBS atomic clock as 'dubious' and 'citation needed': because I can't find it in the histories. Terry0051 ( talk) 01:10, 25 February 2009 (UTC)
By the way, be sure to look at Louis Essen's own recollections on this history, on the excellent website here: [3]. The section on "Atomic Clock" gives a good history of what was happening in the USA and UK in the 1950s. DonPMitchell ( talk) 16:35, 11 August 2009 (UTC)
i think the article about atomic clocks needs a picture of a HP/Agilent/Symmetricom 5071A, because it is the most common/famous atomic clock (caesium based primary frequency standard) in existence and it has most weight in maintaining UTC - every country's time keeping lab has them. 81.206.145.191 21:43, 13 May 2007 (UTC)
I have a very small travel global Atomic Clock and alarm clock. It is Atomic Radio Controlled. It has to be manually set to: US, UK, Japan and EU via a button on the back. It does not change on its own as I fly from time zone to time zone.
If I am out of range of: England, Switzerland, Japan or the US will the clock no longer sync? In the US the clock wants to sync to Mountain Time due to the Atomic Clock is located in Colorado. Colorado is on Mountain Time.
How does a travel Atomic Clock differ from a stationary clock? My stationary clock updates on its own when it unplugged and plugged in again. If the power goes out the clock resets on its own. A travel clock requires a manual reset, selecting the country for the Atomic Clock and sometimes changing Daylight Savings Time.
Why does the page on Atomic Clocks not cover the small travel version as well? Bree25 ( talk) 02:47, 30 April 2013 (UTC)
"National standards agencies maintain an accuracy of 10-9 seconds per day"
So I set up my brand new atomic clock, go away for 3 million years, and come back to find out it is off by one second. Compared to what? Another atomic clock? I don't see what else it could be if, by definition, an atomic clock is the standard. -- Chauncey27 19:21, 24 December 2005 (UTC)
I am working on improving this article to reach B class status. I am thinking of reorganizing the sections as follows:
I don't think Power Consumption should be a section because it is very small and is not a critical but short role in the article. ScientistBuilder ( talk) 01:28, 15 February 2022 (UTC)
If we try to respond to that long list of suggestions, the thread will splinter into incomprehensible spaghetti. I suggest that you pick whichever section you think is the most egregious and open a new thread. Be patient, these things take time. Constant314 ( talk) 01:43, 16 February 2022 (UTC)
I am wondering if it better to use zeptosecond or 10^-21 seconds or if both are acceptable in the article. I think it is helpful to add the power for reference. Which is best? Use International System of Unit prefixed word, power of 10, both at once, or both are acceptable. ScientistBuilder ( talk) 01:05, 16 February 2022 (UTC)
There has been a bit of dubious content added about chip scale atomic clocks that are attributed to an Article in Wired Magazine. If you look carefully, you will see that the content of the article in not from the staff of Wired, but it is "Partner Content" from SYMMETRICOM. In other words, likely marketing hype. The stuff about IEDs, jamming, drones, and undersea exploration needs a reliable source, and I suspect that those applications do not need atomic clock accuracy. Constant314 ( talk) 03:20, 15 February 2022 (UTC)
Definitely not. I removed this text from the article.
Atomic timekeeping forms the basis of the world's financial system by accurately recording the exact time of financial transactions. [1]
Well, of course, atomic time does underly all time keeping in the modern world. But it required? No. The communications and financial networks are set up to operate plesiosynchronously using quartz time (or worse). What happens when the network operates plesiosynchronously? You get what is called a controlled slip. The world works on 256 bit frames. A controlled slip is the lost or duplication of a frame. In plesiosynchronous operation that occurs about once every six hours. In other words, you get a few bit errors. That is not the only source of bit errors, so the communication and financial networks need some fault tolerance. That can be redundancy to allow the error to be corrected at the receiving end, or it can involve retransmission. But the recovery is built in.
What atomic clocks buy you is that you can spend less man-hours on keeping your clocks synchronized. The old Bell system had one atomic clock and distributed time to the rest of the US and Canada. Each class 1 office synchronized its clock to the master clock. Each class 2 office synced to a class 1 office and so forth down to class 5. As atomic clocks become cheaper, it is economically feasible to push atomic clocks further down into the hierarchy. The whole thing only needed synchronization. The absolute accuracy of the clock was never important. As you push atomic clocks down into the network, it increases resilience. If an office loses it connection to the time source and it has its own already synchronized clock, it can operate plesiosynchronous for a long time without experiencing additional frame slips.
Let's look at what the source says. "Such accurate time is also used to timestamp financial transactions so that we know exactly when trades are happening, which can mean the difference between making a fortune and going broke." That is pretty accurate. Since atomic clock derived time is typically available, the time stamp is typically based on atomic time. Nowhere is it said that atomic time is essential. Nowhere is it implied that the financial system would collapse without atomic time. In fact, I can guarantee that the financial system will keep chugging along on quartz time.
The source also says, "Accurate time is also necessary for synchronizing communications signals so that, for instance, your call isn’t lost as you travel between cellphone towers." Notice that it said, "accurate time" and not "atomic time". Inferring that "accurate time" means "atomic time" is an example of synthesis ( WP:SYN) which leads to an incorrect conclusion. That is why we don't like it. That bit about losing your cell phone call is a bit of grand standing. Good old NIST is keeping you from losing phone calls and going broke. Remember the purpose of the blog. In this case it is PR for NIST. Quartz time will be good enough to not lose cell phone calls.
Constant314 ( talk) 01:26, 16 February 2022 (UTC)
On the subject of whether atomic time is required for financial transactions: the answer is yes. This is an important new application which should be mentioned, the development in recent years of high frequency trading [4] [5] [6] This means large investment firms using microwave links to exploit millisecond price differences in stocks and bonds between exchanges located in different cities, for arbitrage. To avoid conflicts, exchanges have recently gone to UTC timestamp standards for trades [7]. Due to the availability of GPS and NTP sources this may or may not require actual atomic clocks at trading houses, but definitely requires UTC atomic time standards synchronized to milliseconds in financial firms across the world.-- Chetvorno TALK 02:59, 16 February 2022 (UTC)
Because the orders are placed from locations around the world, they frequently arrive at the exchange’s computers out of sequence. The new system allows each computer to time stamp an order when it takes place.
As a result, the trades can be sorted and executed in correct sequence. In a networked marketplace, this precision is necessary not only to prevent illicit trading on advance information known as “front-running,” but also to ensure the fair placement of orders.
References
{{u|
Mark viking}} {
Talk}
05:07, 16 February 2022 (UTC)
How should I remove the section on power consumption? I think it could be merged with a new section on how atomic clocks are built and constructed that makes up the second half of the Mechanism section (see New Section Organization and goal to reach B class status above for explanation). ScientistBuilder ( talk) 02:11, 16 February 2022 (UTC)
Is there an organization similar to NIST or the UK's National Physical Laboratory in the EU? I am looking for other sites that engage in atomic clock research. ScientistBuilder ( talk) 02:04, 16 February 2022 (UTC)
I am working on a way to add information about how atomic clocks are built and constructed. Some material I would put in are:
ScientistBuilder ( talk) 02:20, 16 February 2022 (UTC)
I don't think NASA's project is important enough to the history of atomic clocks to be included in the history section. This is specific to NASA and not representative of the field of atomic clocks overall. This is not an active developed program as far as I can tell and more of an narrowly defined subject. I think it should be moved to the Construction section. In place of the NASA project, I propose a paragraph about optical clocks and ytterbium in the 2000s. ScientistBuilder ( talk) 13:58, 16 February 2022 (UTC)
I think the lead should be organized and rewritten to have no bullet points. Having a list in the lead is not what a good lead has. I propose turning the two bullet points into sentences. ScientistBuilder ( talk) 21:09, 16 February 2022 (UTC)
I think there should be a separate section explaining how clocks lock on to an atomic frequency transition emission. This would include the following:
I'll do a block diagram for a cesium clock, unless someone else has already started on it. Constant314 ( talk) 22:48, 16 February 2022 (UTC)
I am proposing to remove the sentence on Fabry Perot interferometers because there are not that many cases of Fabry Perot interferometers in the literature for atomic clocks on NISt and other websites. I think the main improvements were cooling with lasers and optical combs. ScientistBuilder ( talk) 03:04, 16 February 2022 (UTC)
There are multiple paragraphs in different sections that cover the definition of the second. I want to remove the material in the Time Measurement section and put any material that is there and not in the How Atomic Clocks Work Section in the How Atomic Clocks Work section. ScientistBuilder ( talk) 19:20, 19 February 2022 (UTC)
Atomic clocks with caesium use microwaves to measure time. The atomic clock measures the frequency of the microwaves. The atomic clock sends a microwave to excite the atoms. The microwave is measured and if it not 9192631770Hz, the microwave is corrected. ScientistBuilder ( talk) 14:57, 19 February 2022 (UTC)
The article has too much information about the accuracy of specific clocks. I propose removing all parts that mention a clock that reached a new level of accuracy unless it achieved a world record such as to . The section on accuracy could be simplified. ScientistBuilder ( talk) 21:24, 20 February 2022 (UTC)
the accuracy section does not define . Therefore, I propose removing the use of the term. ScientistBuilder ( talk) 21:25, 20 February 2022 (UTC)
The article on atomic clocks does not need to include a discussion about the differences of UTC and UT1 and Earth's rotation so I am removing UT1. ScientistBuilder ( talk) 22:51, 20 February 2022 (UTC)
I propose changing the lead's first sentence to "An atomic clock is a clock that measures time by monitoring the oscillations of atoms." The current sentence is pretty technical and I think it would be better to start with a more understandable and intuitive sentence and go into how electromagnetic radiation is used later. ScientistBuilder ( talk) 00:54, 21 February 2022 (UTC)
I propose to simplify the sentence at the end of the lead that states atomic clocks deviate by at most a nanosecond every day (about one part in 10^14). This is because the accuracy of an atomic clock is often evaluated by the deviation from the second but not by the deviation from the second over a day. ScientistBuilder ( talk) 21:11, 16 February 2022 (UTC)
There are some good images of atomic clocks from the BIPM at https://www.bipm.org/en/-/2021-12-21-record-tai. I would like to find a way to put them in the article. I have added a graph of the accuracy of atomic clocks. I am uploading the rest to Wikimedia Commons:
I want to add more images of atomic clocks. Adding images of atomic clocks from around the globe contributes to a global perspective and not just NIST.
( talk) 01:49, 18 February 2022 (UTC)
I am proposing the following revision to the first subsection: "James Clerk Maxwell and Lord Kelvin were the first to argue that radiation could be used to keep track of time. The first practical considerations of how an atomic clock might work were made by Isidor Rabi in 1939. He proposed the concept in 1945, which led to a demonstration of a clock based on ammonia in 1949. This led to to the first accurate atomic clock being built at the National Physical Laboratory in the United Kingdom with caesium atoms." ScientistBuilder ( talk) 02:31, 21 February 2022 (UTC)
I am working on improving the section's narrative about the history of time and the tropical year and now caesium clocks. ScientistBuilder ( talk) 02:38, 22 February 2022 (UTC)
ScientistBuilder ( talk) 02:40, 22 February 2022 (UTC)
For some reason a reference to James Clerk Maxwell and Lord Kelvin was removed. I am wondering why a sentence about the first people to propose the atomic clock is too much to include or why it was removed. ScientistBuilder ( talk) 02:45, 22 February 2022 (UTC)
I propose the History section should not include optical clock research and other experimental advances since the 1990s like fountains and ion traps. I think its better to put these later in the article. ScientistBuilder ( talk) 02:59, 21 February 2022 (UTC)
@Chetvorno
The paragraph in the International System of Units Definition includes information that is in the History section. I propose moving the information that is not in the History section there and deleting the rest. ScientistBuilder ( talk) 15:27, 22 February 2022 (UTC)
I am working on improving the article but there is a lot of redundant information about redefining the second, optical clocks and discoveries. I would like to reduce this redundancy by moving and reorganizing the sections. I propose removing the history section because to understand the history, the mechanism should be explained first. ScientistBuilder ( talk) 16:12, 22 February 2022 (UTC)
Femtosecond Combs Section Laser Cooling Section Applications of More accurate clocks Redefining the second This involves subjects such as fiber optic communication of time, GNSS
Cite error: There are <ref group=Microsemi>
tags on this page, but the references will not show without a {{reflist|group=Microsemi}}
template (see the
help page).