Highly accurate atomic clocks that make an error of one second every 300 million years. This watch, which replaced old model, which allowed an error of one second in a hundred million years, now sets the standard for American civil time. Lenta.ru decided to recall the history of the creation of atomic clocks.
First atom
In order to create a clock, it is enough to use any periodic process. And the history of the appearance of time measuring instruments is partly the history of the emergence of either new energy sources or new oscillatory systems used in watches. The simplest clock is probably the sun clock: for its operation you only need the Sun and an object that casts a shadow. The disadvantages of this method of determining time are obvious. Water and hourglasses are no better either: they are suitable only for measuring relatively short periods of time.
The most ancient mechanical watches were found in 1901 near the island of Antikythera on a sunken ship in the Aegean Sea. They contain about 30 bronze gears in a wooden case measuring 33 by 18 by 10 centimeters and date from about the hundredth year BC.
For almost two thousand years, mechanical watches were the most accurate and reliable. The appearance in 1657 of Christian Huygens's classic work “The Pendulum Clock” (“Horologium oscillatorium, sive de motu pendulorum an horologia aptato demonstrationes geometrica”), describing a time-keeping device with a pendulum as an oscillating system, was probably the apogee in the history of the development of mechanical instruments of such a type.
However, astronomers and sailors still used the starry sky and maps to determine their location and exact time. The first electric clock was invented in 1814 by Francis Ronalds. However, the first such device was inaccurate due to sensitivity to temperature changes.
The further history of watches is connected with the use of various oscillating systems in devices. Introduced in 1927 by Bell Laboratories, quartz clocks exploited the piezoelectric properties of a quartz crystal: when exposed to electric current the crystal begins to shrink. Modern quartz chronometers can be accurate to within 0.3 seconds per month. However, because quartz is susceptible to aging, watches become less accurate over time.
With development atomic physics Scientists have proposed using particles of matter as oscillatory systems. This is how the first atomic clocks appeared. The idea of the possibility of using atomic vibrations of hydrogen to measure time was proposed back in 1879 by the English physicist Lord Kelvin, but only by the middle of the 20th century did this become possible.
Reproduction of a painting by Hubert von Herkomer (1907)
In the 1930s, American physicist and nuclear magnetic resonance pioneer Isidor Rabi began working on a cesium-133 atomic clock, but the outbreak of war prevented him from doing so. After the war, in 1949, the first molecular clock using ammonia molecules was created at the US National Standards Committee with the participation of Harold Lyonson. But the first such time measuring instruments were not as accurate as modern atomic clocks.
The relatively low accuracy was due to the fact that due to the interaction of ammonia molecules with each other and with the walls of the container in which this substance was located, the energy of the molecules changed and their spectral lines broadened. This effect is very similar to friction in a mechanical watch.
Later, in 1955, Louis Essen of the UK National Physical Laboratory introduced the first cesium-133 atomic clock. This clock accumulated an error of one second over a million years. The device was named NBS-1 and began to be considered a cesium frequency standard.
Schematic diagram An atomic clock consists of a quartz oscillator controlled by a discriminator using a feedback circuit. The oscillator takes advantage of the piezoelectric properties of quartz, while the discriminator uses the energetic vibrations of the atoms so that the vibrations of the quartz are tracked by signals from transitions from different energy levels in the atoms or molecules. Between the generator and the discriminator there is a compensator tuned to the frequency of atomic vibrations and comparing it with the vibration frequency of the crystal.
The atoms used in the clock must provide stable vibrations. For each frequency of electromagnetic radiation, there are atoms: calcium, strontium, rubidium, cesium, hydrogen. Or even molecules of ammonia and iodine.
Time standard
With the advent of atomic time measuring instruments, it became possible to use them as a universal standard for determining the second. Since 1884, Greenwich Time, considered the world standard, has given way to the standard of atomic clocks. In 1967, by decision of the 12th General Conference of Weights and Measures, one second was defined as the duration of 9192631770 periods of radiation corresponding to the transition between two hyperfine levels of the ground state of the cesium-133 atom. This definition of the second does not depend on astronomical parameters and can be reproduced anywhere on the planet. Cesium-133, used in the atomic clock standard, is the only stable isotope of cesium with 100% abundance on Earth.
Atomic clocks are also used in satellite navigation systems; they are necessary to determine the exact time and satellite coordinates. Thus, each GPS satellite has four sets of such clocks: two rubidium and two cesium, which ensure signal transmission accuracy of 50 nanoseconds. The Russian satellites of the GLONASS system are also equipped with cesium and rubidium atomic time measuring instruments, and the satellites of the deploying European Galileo geopositioning system are equipped with hydrogen and rubidium ones.
The accuracy of hydrogen clocks is the highest. It is 0.45 nanoseconds in 12 hours. Apparently, Galileo's use of such accurate clocks will make this navigation system a leader already in 2015, when there will be 18 of its satellites in orbit.
Compact atomic clock
Hewlett-Packard became the first company to develop a compact atomic clock. In 1964, she created the HP 5060A cesium device, the size of a large suitcase. The company continued to develop this direction, but in 2005 it sold its division developing atomic clocks to Symmetricom.
In 2011, specialists from Draper Laboratory and Sandia National Laboratories developed and Symmetricom released the first miniature atomic clock, Quantum. At the time of release, they cost about 15 thousand dollars, were enclosed in a sealed case measuring 40 by 35 by 11 millimeters and weighed 35 grams. The power consumption of the clock was less than 120 milliwatts. They were originally developed by order of the Pentagon and were intended to serve navigation systems operating independently of GPS systems, for example, deep under water or ground.
Already at the end of 2013 American company Bathys Hawaii introduced the first atomic wristwatch. They use the SA.45s chip manufactured by Symmetricom as the main component. Inside the chip there is a capsule with cesium-133. The design of the watch also includes photocells and a low-power laser. The latter provides heating of gaseous cesium, as a result of which its atoms begin to move from one energy level another. The measurement of time is precisely carried out by recording such a transition. The cost of a new device is about 12 thousand dollars.
Trends towards miniaturization, autonomy and precision will lead to the fact that in the near future new devices using atomic clocks will appear in all areas human life, starting from space research on orbiting satellites and stations to household applications in room and wrist systems.
We often hear the phrase that atomic clocks always show exact time. But from their name it is difficult to understand why atomic clocks are the most accurate or how they work.
Just because the name contains the word “atomic” does not mean that the watch poses a danger to life, even if thoughts of atomic bomb or nuclear power plant. IN in this case we're just talking about how the watch works. If in an ordinary mechanical watch the oscillatory movements are performed by gears and their movements are counted, then in an atomic clock the oscillations of electrons inside atoms are counted. To better understand the principle of operation, let's remember the physics of elementary particles.
All substances in our world are made of atoms. Atoms consist of protons, neutrons and electrons. Protons and neutrons combine with each other to form a nucleus, which is also called a nucleon. Electrons move around the nucleus, which can be at different energy levels. The most interesting thing is that when absorbing or releasing energy, an electron can move from its energy level to a higher or lower one. An electron can obtain energy from electromagnetic radiation, absorbing or emitting electromagnetic radiation of a certain frequency with each transition.
Most often there are watches in which atoms of the element Cesium -133 are used for change. If in 1 second the pendulum regular watch commits 1 oscillatory motion, then electrons in atomic clocks based on Cesium-133, when transitioning from one energy level to another, they emit electromagnetic radiation with a frequency of 9192631770 Hz. It turns out that one second is divided into exactly this number of intervals if it is calculated in atomic clocks. This value was officially adopted by the international community in 1967. Imagine a huge dial with not 60, but 9192631770 divisions, which make up only 1 second. It is not surprising that atomic clocks are so accurate and have a number of advantages: atoms are not subject to aging, do not wear out, and the oscillation frequency will always be the same for one chemical element, thanks to which it is possible to synchronously compare, for example, the readings of atomic clocks far in space and on Earth, without fear of errors.
Thanks to atomic clocks, humanity was able to test in practice the correctness of the theory of relativity and make sure that it is better than on Earth. Atomic clocks are installed on many satellites and spacecraft; they are used for telecommunications needs, for mobile communications, and they are used to compare the exact time on the entire planet. Without exaggeration, it was thanks to the invention of atomic clocks that humanity was able to enter the era of high technology.
How do atomic clocks work?
Cesium-133 is heated by evaporating cesium atoms, which are passed through a magnetic field, where atoms with the desired energy states are selected.
The selected atoms then pass through a magnetic field with a frequency close to 9192631770 Hz, which is created by a quartz oscillator. Under the influence of the field, cesium atoms again change energy states and fall on a detector, which records when greatest number the incoming atoms will have the “correct” energy state. Maximum amount atoms with a changed energy state indicates that the frequency of the microwave field is selected correctly, and then its value is fed into an electronic device - a frequency divider, which, reducing the frequency by an integer number of times, receives the number 1, which is the reference second.
Thus, cesium atoms are used to check the correctness of the frequency magnetic field, created by a crystal oscillator, helping to maintain it at a constant value.
This is interesting: Although the current atomic clocks are unprecedentedly accurate and can run for millions of years without errors, physicists are not going to stop there. Using atoms of various chemical elements, they are constantly working to improve the accuracy of atomic clocks. Among the latest inventions is the atomic clock strontium, which are three times more accurate than their cesium counterpart. To lag behind just a second, they will need 15 billion years - time exceeding the age of our Universe...
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An atomic clock is a device for very precise measurement of time. They got their name from the principle of their operation, since the natural vibrations of molecules or atoms are used as the period. Atomic clocks have found very wide application in navigation, in the space industry, for determining the location of satellites, in the military field, for the detection of aircraft, and also in telecommunications.
As you can see, there are a lot of areas of application, but why do they all need such accuracy, because today the error of conventional atomic clocks is only 1 second in 30 million years? But there is something even more precise. Everything is understandable, because time is used to calculate distances, and there a small error can lead to hundreds of meters, or even kilometers, if we take cosmic distances. For example, take the American GPS navigation system, when using conventional electronic watch, the error in measuring coordinates will be quite significant, which can affect all other calculations, and this can lead to consequences when it comes to space technologies. Naturally, for GPS receivers in mobile devices and other gadgets, greater accuracy is not at all important.
The most accurate time in Moscow and the world can be found on the official website - the “precise current time server” www.timeserver.ru
What are atomic clocks made of?
An atomic clock consists of several main parts: a quartz oscillator, a quantum discriminator and electronics units. The main one that sets the reference is a quartz oscillator, which is built on quartz crystals and, as a rule, produces a standard frequency of 10, 5, 2.5 MHz. Because stable work quartz without error is quite small; it must be constantly adjusted.
The quantum discriminator records the frequency of the atomic line, and it is compared in the frequency-phase comparator with the frequency of the quartz oscillator. The comparator has feedback to the quartz oscillator to adjust it in case of frequency mismatch.
Atomic clocks cannot be built on all atoms. The most optimal is the cesium atom. It refers to the primary one by which all others are compared suitable materials, for example, such as: strontium, rubidium, calcium. The primary standard is absolutely suitable for measuring precise time, which is why it is called primary.
The most accurate atomic clock in the world
To date most accurate atomic clock are located in the UK (officially adopted). Their error is only 1 second in 138 million years. They are the standard for the national time standards of many countries, including the United States, and also determine international atomic time. But the kingdom contains not the most accurate clocks on Earth.
most accurate atomic clock photo
The US announced that it had developed experimental type precise clocks on cesium atoms, their error was 1 second in almost 1.5 billion years. Science in this area does not stand still and is developing at a rapid pace.
Atomic clock January 27th, 2016
The birthplace of the world's first pocket watch with a built-in atomic time standard will not be Switzerland or even Japan. The idea of their creation originated in the heart of Great Britain at the London brand Hoptroff
Atomic clocks, or as they are also called “quantum clocks,” are a device that measures time using natural vibrations associated with processes occurring at the level of atoms or molecules. Richard Hoptroff decided that it was time for modern gentlemen who are interested in ultra-technological devices to exchange their mechanical pocket watches for something more extravagant and unusual, and also in line with modern urban trends.
Thus, the public were shown elegant in their own way appearance pocket atomic clock Hoptroff No. 10, which can surprise the modern generation, sophisticated with an abundance of gadgets, not only with its retro style and fantastic accuracy, but also with its service life. According to the developers, having this watch with you, you can remain the most punctual person for at least 5 billion years.
What else can you find out interesting about them...
Photo 2. 
For all those who have never been interested in such watches, it is worth briefly explaining the principle of their operation. There is nothing inside the “atomic device” that resembles a classic mechanical watch. In Hoptroff no. 10 there are no mechanical parts as such. Instead, atomic pocket watches are equipped with a sealed chamber filled with a radioactive gas, the temperature of which is controlled by a special furnace. Accurate timekeeping occurs as follows: lasers excite the atoms of a chemical element, which is a kind of “filler” of the clock, and the resonator records and measures each atomic transition. Today the basic element similar devices is cesium. If we recall the SI system of units, then in it the value of a second is related to the number of periods of electromagnetic radiation during the transition of cesium-133 atoms from one energy level to another.
Photo 3. 
If in smartphones the heart of the device is considered to be a processor chip, then in Hoptroff No. 10 this role is taken on by the reference time generator module. It is supplied by Symmetricom, and the chip itself was initially intended for use in the military industry - in unmanned aerial vehicles.
The CSAC atomic clock is equipped with a temperature-controlled thermostat, which contains a chamber containing cesium vapor. Under the influence of a laser on cesium-133 atoms, their transition from one energy state to another begins, which is measured using a microwave resonator. Since 1967, the International System of Units (SI) has defined one second as 9,192,631,770 periods of electromagnetic radiation produced during the transition between two hyperfine levels of the ground state of a cesium-133 atom. Based on this, it is difficult to imagine a more technically accurate cesium-based watch. Over time, given the latest advances in the field of time measurement, the accuracy of new optical clocks based on an aluminum ion pulsating at the frequency of ultraviolet radiation (100,000 times higher than the microwave frequencies of cesium clocks) will be hundreds of times higher than the accuracy of atomic chronometers. To put it simply, Hoptroff's new Pocket Model No.10 has a running error of 0.0015 seconds per year, which is 2.4 million times better than COSC standards.
Photo 4. 
The functional side of the device is also on the verge of fantasy. With its help you can find out: time, date, day of the week, year, latitude and longitude in different sizes, pressure, humidity, sidereal hours and minutes, tide forecast and many other indicators. The watch comes in gold, and 3D printing is planned to be used to create its case from the precious metal.
Richard Hoptrof sincerely believes that this particular option for producing his brainchild is the most preferable. To slightly change the design component of the structure, it will not be necessary to rebuild the production line at all, but to use the functional flexibility of the 3D printing device for this. However, it is worth noting that the prototype of the watch shown was made in the classical way.
Photo 5. 
Time is very expensive these days, and the Hoptroff No. 10 is a direct confirmation of this. According to preliminary information, the first batch of atomic devices will be 12 units, and as for the cost, the price for 1 copy will be $78,000.
Photo 6. 
According to Richard Hoptroff, managing director of the brand, Hoptroff's London location played a key role in the emergence of this idea. “In our quartz movements we use a high-precision oscillating system with a GPS signal. But in the center of London it is not so easy to catch this very signal. One day, during a trip to the Greenwich Observatory, I saw a Hewlett Packard atomic clock there and decided to buy something similar for myself via the Internet. And I couldn't. Instead, I came across information about a chip from Symmetricon, and after three days of thinking, I realized that it would be perfect for a pocket watch.”
The chip in question is the SA.45s cesium atomic clock (CSAC), one of the first generation of miniature atomic clocks for GPS receivers, backpack radios and unmanned vehicles. Despite its modest dimensions (40 mm x 34.75 mm), the wrist watch It's still unlikely to fit. Therefore, Hoptroff decided to equip them with a pocket model of rather respectable dimensions (82 mm in diameter).
In addition to being the most accurate watch in the world, the Hoptroff No 10 (the brand's tenth movement) also claims to be the first gold case made using 3D printing technology. Hoptroff cannot yet say with certainty how much gold will be required to make the case (work on the first prototype was completed when the issue had already gone to press), but estimates that its cost will be “at least several thousand pounds.” And considering all that volume scientific research, required to develop the product (take, for example, the function of calculating the ebb and flow of tides using harmonic constants for 3 thousand different ports), we can expect its final retail price to be about 50 thousand pounds sterling.
Gold body of model No. 10 as it comes out of the 3D printer and in finished form
Buyers automatically become members of an exclusive club and will be required to sign a written pledge not to use the atomic clock chip as a weapon. “This is one of the conditions of our contract with the supplier,” explains Mr. Hoptroff, “since the atomic chip was originally used in missile guidance systems.” Not much to pay for the opportunity to have a watch with impeccable accuracy.
The lucky owners of the No.10 from Hoptroff will have much more at their disposal than just a high-precision watch. The model also functions as a pocket navigation device, allowing one to determine longitude with an accuracy of one nautical mile, even after many years at sea, using a simple sextant. The model will receive two dials, but the design of one of them is still kept secret. The other is a whirlwind of counters displaying as many as 28 complications: from all possible chronometric functions and calendar indicators to a compass, thermometer, hygrometer (a device for measuring humidity levels), barometer, latitude and longitude counters and a high/low tide indicator. And this is not to mention the vital indicators of the state of the atomic thermostat.
Hoptroff has plans to produce a number of new products, including an electronic version of George Daniels' legendary Space Traveler complication watch. Work is currently underway on them, the goal of which is to integrate Bluetooth technology into the watch to save personal information owner and provide automatic adjustment of complications such as the moon phase indicator.
The first copies of No.10 will appear in next year, in the meantime, the company is looking for suitable partners among retailers. “We could, of course, try to sell it online, but this is a premium model, so you still need to hold it in your hands to really appreciate it. This means that we will still have to use the services of retailers, and we are ready to start negotiations,” says Mr. Hoptroff in conclusion.
And even The original article is on the website InfoGlaz.rf Link to the article from which this copy was made -
Atomic clocks are the most accurate time measuring instruments that exist today, and are becoming increasingly important as they develop and become more complex. modern technologies.
Principle of operation
Atomic clocks do not keep accurate time thanks to radioactive decay, as their name might suggest, but using vibrations of nuclei and the electrons surrounding them. Their frequency is determined by the mass of the nucleus, gravity and the electrostatic “balancer” between the positively charged nucleus and electrons. This does not quite correspond to a regular watch movement. Atomic clocks are more reliable time keepers because their oscillations do not change depending on such factors environment, such as humidity, temperature or pressure.
Evolution of atomic clocks
Over the years, scientists have realized that atoms have resonant frequencies related to each's ability to absorb and emit electromagnetic radiation. In the 1930s and 1940s, high-frequency communications and radar equipment was developed that could interface with the resonance frequencies of atoms and molecules. This contributed to the idea of a watch.
The first examples were built in 1949 by the National Institute of Standards and Technology (NIST). Ammonia was used as a vibration source. However, they were not much more accurate than the existing time standard, and cesium was used in the next generation.
New standard
The change in the precision of time measurement was so great that in 1967 the General Conference on Weights and Measures defined the SI second as 9,192,631,770 vibrations of a cesium atom at its resonant frequency. This meant that time was no longer related to the movement of the Earth. The world's most stable atomic clock was created in 1968 and was used as part of the NIST timekeeping system until the 1990s.
Improvement car
One of latest achievements in this area is laser cooling. This improved the signal-to-noise ratio and reduced the uncertainty in the clock signal. Housing this cooling system and other equipment used to improve cesium clocks would require space the size of a railroad car, although commercial versions could fit in a suitcase. One of these laboratory installations keeps time in Boulder, Colorado, and is the most accurate clock on Earth. They are only wrong by 2 nanoseconds per day, or 1 second per 1.4 million years.
Complex technology
This enormous precision is the result of complex technological process. First, liquid cesium is placed in a furnace and heated until it turns into a gas. The metal atoms exit at high speed through a small opening in the furnace. Electromagnets cause them to split into separate beams with different energies. The required beam passes through a U-shaped hole, and the atoms are irradiated with microwave energy with a frequency of 9,192,631,770 Hz. Thanks to this, they are excited and move into a different energy state. The magnetic field then filters out other energy states of the atoms.
The detector reacts to cesium and shows a maximum at the correct frequency value. This is necessary to configure the quartz oscillator that controls the clock mechanism. Dividing its frequency by 9.192.631.770 gives one pulse per second.
Not just cesium
Although the most common atomic clocks use the properties of cesium, there are other types. They differ in the element used and the means for determining changes in energy level. Other materials are hydrogen and rubidium. Hydrogen atomic clocks function similarly to cesium clocks, but require a container with walls made of a special material that prevents the atoms from losing energy too quickly. Rubidium watches are the simplest and most compact. In them, a glass cell filled with rubidium gas changes the absorption of light when exposed to ultrahigh frequency.
Who needs accurate time?
Today, time can be measured with extreme precision, but why is this important? This is necessary in systems such as Cell phones, Internet, GPS, aviation programs and digital television. At first glance this is not obvious.
An example of how precise time is used is in packet synchronization. Thousands of telephone calls pass through the average communication line. This is only possible because the conversation is not transmitted completely. The telecommunications company splits it into small packets and even skips some of the information. They then pass through the line along with packets of other conversations and are restored at the other end without mixing. The telephone exchange's clocking system can determine which packets belong to a given conversation by the exact time the information was sent.
GPS
Another implementation of precise time is a global positioning system. It consists of 24 satellites that transmit their coordinates and time. Any GPS receiver can connect to them and compare broadcast times. The difference allows the user to determine their location. If these clocks were not very accurate, then the GPS system would be impractical and unreliable.
The limit of perfection
With the development of technology and atomic clocks, the inaccuracies of the Universe became noticeable. The earth moves unevenly, causing random variations in the length of years and days. In the past, these changes would have gone unnoticed because the tools for measuring time were too imprecise. However, much to the frustration of researchers and scientists, the time of atomic clocks has to be adjusted to compensate for anomalies real world. They are amazing tools that help advance modern technology, but their excellence is limited by the limits set by nature itself.