Atomic clock working principle. atomic clock

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What "watchmakers" invented and perfected this extremely precise movement? Is there a replacement for him? Let's try to figure it out.

In 2012, atomic timekeeping will celebrate its 45th anniversary. In 1967, the category of time in international system units began to be determined not by astronomical scales, but by the cesium frequency standard. It is in common people that they call it an atomic clock.

What is the principle of operation of atomic oscillators? As a source of resonant frequency, these "devices" use the quantum energy levels of atoms or molecules. Quantum mechanics connects with the system atomic nucleus- electrons "several discrete energy levels. Electromagnetic field certain frequency can provoke the transition of this system from low level to a higher one. The opposite phenomenon is also possible: an atom can go from a high energy level to a lower one with energy radiation. Both phenomena can be controlled and these energy interlevel jumps can be fixed, thereby creating a semblance oscillatory circuit. The resonant frequency of this circuit will be equal to the energy difference between the two transition levels, divided by Planck's constant.

The resulting atomic oscillator has undeniable advantages over its astronomical and mechanical predecessors. The resonant frequency of all atoms of the substance chosen for the oscillator will be the same, unlike pendulums and piezocrystals. In addition, atoms do not wear out and do not change their properties over time. Perfect option for an almost perpetual and extremely accurate chronometer.

For the first time, the possibility of using interlevel energy transitions in atoms as a frequency standard was considered back in 1879 by the British physicist William Thomson, better known as Lord Kelvin. He proposed using hydrogen as a source of resonator atoms. However, his research was more theoretical. The science of that time was not yet ready to develop an atomic chronometer.

It took almost a hundred years for Lord Kelvin's idea to become a reality. It was a long time, but the task was not easy either. Turning atoms into ideal pendulums proved more difficult in practice than in theory. The difficulty was in the battle with the so-called resonant width - a small fluctuation in the frequency of absorption and emission of energy as atoms move from level to level. The ratio of the resonant frequency to the resonant width determines the quality of the atomic oscillator. Obviously, the larger the value of the resonant width, the lower the quality of the atomic pendulum. Unfortunately, it is not possible to increase the resonant frequency to improve the quality. It is constant for the atoms of each particular substance. But the resonant width can be reduced by increasing the observation time for atoms.

Technically, this can be achieved as follows: let an external, for example, quartz, oscillator periodically generate electromagnetic radiation, causing the atoms of the donor substance to jump over energy levels. In this case, the task of the tuner of the atomic chronograph is the maximum approximation of the frequency of this quartz oscillator to the resonant frequency of the interlevel transition of atoms. It becomes possible if enough long period observing the vibrations of atoms and creating feedback, which regulates the frequency of quartz.

True, besides the problem of reducing the resonant width in an atomic chronograph, there are many other problems. This is the Doppler effect - a shift in the resonant frequency due to the movement of atoms, and mutual collisions of atoms, causing unplanned energy transitions, and even the influence of the all-pervading energy of dark matter.

For the first time, an attempt at the practical implementation of atomic clocks was made in the thirties of the last century by scientists at Columbia University under the guidance of the future Nobel laureate Dr. Isidore Rabi. Rabi proposed to use the cesium isotope 133 Cs as a source of pendulum atoms. Unfortunately, Rabi's work, which greatly interested NBS, was interrupted by World War II.

After its completion, the championship in the implementation of the atomic chronograph passed to NBS employee Harold Lyons. His atomic oscillator worked on ammonia and gave an error commensurate with the best examples quartz resonators. In 1949, ammonia atomic clocks were demonstrated to the general public. Despite the rather mediocre accuracy, they implemented the basic principles of future generations of atomic chronographs.

The prototype of the cesium atomic clock obtained by Louis Essen provided an accuracy of 1 * 10 -9, while having a resonance width of only 340 Hertz.

A little later the professor Harvard University Norman Ramsey improved on the ideas of Isidore Rabi, reducing the influence of the Doppler effect on the accuracy of measurements. He proposed instead of one long high-frequency pulse exciting the atoms, to use two short ones sent to the arms of the waveguide at some distance from each other. This made it possible to drastically reduce the resonant width and actually made it possible to create atomic oscillators that are an order of magnitude better than their quartz ancestors in accuracy.

In the fifties of the last century, based on the scheme proposed by Norman Ramsey, at the National Physical Laboratory (Great Britain), its employee Louis Essen worked on an atomic oscillator based on the cesium isotope 133 Cs proposed earlier by Rabi. Cesium was not chosen by chance.

Scheme of hyperfine transition levels of atoms of the cesium-133 isotope

Relating to the group alkali metals, cesium atoms are extremely easily excited to jump between energy levels. So, for example, a beam of light is easily capable of knocking out a stream of electrons from the atomic structure of cesium. It is due to this property that cesium is widely used in photodetectors.

The device of a classical cesium oscillator based on the Ramsey waveguide

First official cesium frequency standard NBS-1

A descendant of NBS-1 - the NIST-7 oscillator used laser pumping of a beam of cesium atoms

It took more than four years. After all, fine tuning of atomic clocks was possible only by comparison with existing ephemeris units of time. For four years, the atomic oscillator was calibrated by observing the rotation of the Moon around the Earth using the most accurate lunar camera invented by William Markowitz of the US Naval Observatory.

"Adjustment" of atomic clocks to lunar ephemeris was carried out from 1955 to 1958, after which the device was officially recognized by NBS as a frequency standard. Moreover, the unprecedented accuracy of cesium atomic clocks prompted NBS to change the unit of time in the SI standard. Since 1958, "the duration of 9,192,631,770 periods of radiation corresponding to the transition between two hyperfine levels of the standard state of the cesium-133 isotope atom" has been officially adopted as a second.

Louis Essen's device was named NBS-1 and was considered the first cesium frequency standard.

Over the next thirty years, six modifications of the NBS-1 were developed, the latest of which, NIST-7, created in 1993 by replacing magnets with laser traps, provides an accuracy of 5 * 10 -15 with a resonant width of only sixty-two Hertz.

Comparison table of characteristics of cesium frequency standards used by NBS

Cesium frequency standard	Operating time	Operating time as an official NPFS standard	Resonant Width	Microwave guide length	Error value
NBS-1	1952-1962	1959-1960	300 Hz	55 cm	1*10 -11
NBS-2	1959-1965	1960-1963	110 Hz	164 cm	8*10 -12
NBS-3	1959-1970	1963-1970	48 Hz	366 cm	5*10 -13
NBS-4	1965-1990s	No	130 Hz	52.4 cm	3*10 -13
NBS-5	1966-1974	1972-1974	45 Hz	374 cm	2*10 -13
NBS-6	1974-1993	1975-1993	26 Hz	374 cm	8*10 -14
NBS-7	1988-2001	1993-1998	62 Hz	155 cm	5*10 -15

NBS devices are stationary test benches, which makes it possible to attribute them to standards rather than to practically used oscillators. But for purely practical purposes, Hewlett-Packard has worked for the benefit of the cesium frequency standard. In 1964, the future computer giant created a compact version of the cesium frequency standard - the HP 5060A device.

Calibrated using NBS standards, the HP 5060 frequency standards fit into a typical radio equipment rack and had commercial success. It was thanks to the cesium frequency standard set by Hewlett-Packard that the unprecedented accuracy of atomic clocks went to the masses.

Hewlett-Packard 5060A.

As a result, such things as satellite television and communications became possible, global systems navigation and information network time synchronization services. There were many applications of the atomic chronograph technology brought to an industrial design. At the same time, Hewlett-Packard did not stop there and constantly improve the quality of cesium standards and their weight and size indicators.

Hewlett-Packard family of atomic clocks

In 2005, Hewlett-Packard's atomic clock division was sold to Simmetricom.

Along with cesium, whose reserves in nature are very limited, and the demand for it in a variety of technological fields extremely large, rubidium was used as a donor substance, its properties are very close to cesium.

It would seem that the existing scheme of atomic clocks has been brought to perfection. Meanwhile, it had an unfortunate drawback, the elimination of which became possible in the second generation of cesium frequency standards, called cesium fountains.

Fountains of time and optical molasses

Despite the highest accuracy of the NIST-7 atomic chronometer, which uses laser detection of the state of cesium atoms, its scheme does not fundamentally differ from the schemes of the first versions of cesium frequency standards.

And the design flaw of all these schemes is that it is fundamentally impossible to control the propagation speed of a beam of cesium atoms moving in a waveguide. And this despite the fact that the speed of movement of cesium atoms at room temperature is one hundred meters per second. Quite quickly.

That is why all modifications of cesium standards are a search for a balance between the size of the waveguide, which has time to act on fast cesium atoms at two points, and the accuracy of detecting the results of this effect. The smaller the waveguide, the more difficult it is to make successive electromagnetic pulses affecting the same atoms.

But what if we find a way to reduce the speed of movement of cesium atoms? It was this thought that the student of the Massachusetts Institute of Technology Jerrold Zacharius, who studied the influence of gravity on the behavior of atoms in the late forties of the last century. Later, involved in the development of a variant of the cesium frequency standard Atomichron, Zacharius proposed the idea of ​​a cesium fountain - a method to reduce the speed of cesium atoms to one centimeter per second and get rid of the two-arm waveguide of traditional atomic oscillators.

Zacharius' idea was simple. What if you run cesium atoms inside the oscillator vertically? Then the same atoms will pass through the detector twice: the first time when traveling up, and the second time down, where they will rush under the action of gravity. At the same time, the downward movement of atoms will be much slower than their take-off, because during the journey in the fountain they lose energy. Unfortunately, in the fifties of the last century, Zacharius could not realize his ideas. In his experimental facilities atoms moving up interacted with those falling down, which reduced the accuracy of detection.

The idea of ​​Zacharius returned only in the eighties. Scientists at Stanford University, led by Steven Chu, have found a way to implement the Zacharius Fountain using a technique they call "optical molasses."

In the Chu cesium fountain, a cloud of cesium atoms shot upwards is pre-cooled by a system of three pairs of oppositely directed lasers having a resonant frequency just below the optical resonance of cesium atoms.

Diagram of a cesium fountain with optical molasses.

Cooled by lasers, cesium atoms begin to move slowly, as if through molasses. Their speed drops to three meters per second. Reducing the speed of atoms gives researchers the opportunity to more accurately detect the state (it's much easier to see the numbers of a car moving at a speed of one kilometer per hour than a car moving at a speed of one hundred kilometers per hour).

A ball of cooled cesium atoms is launched up about a meter, passing a waveguide along the way, through which an electromagnetic field of resonant frequency acts on the atoms. And the detector of the system captures the change in the state of atoms for the first time. Having reached the "ceiling", the cooled atoms begin to fall due to gravity and pass through the waveguide a second time. On the way back the detector captures their state again. Since the atoms move extremely slowly, their flight in the form of a fairly dense cloud is easy to control, which means that there will be no atoms flying up and down at the same time in the fountain.

Chu's cesium fountain setup was adopted by NBS as the frequency standard in 1998 and named NIST-F1. Its error was 4 * 10 -16, which means that NIST-F1 was more accurate than its predecessor NIST-7.

In fact, NIST-F1 reached the limit of accuracy in measuring the state of cesium atoms. But scientists did not stop at this victory. They decided to eliminate the error introduced into the work of atomic clocks by the radiation of a completely black body - the result of the interaction of cesium atoms with the thermal radiation of the body of the installation in which they move. In the new NIST-F2 atomic chronograph, a cesium fountain was placed in a cryogenic chamber, reducing the black body radiation to almost zero. The NIST-F2 margin of error is an incredible 3*10 -17 .

Graph of the error reduction of variants of cesium frequency standards

Currently, atomic clocks based on cesium fountains give humanity the most accurate standard of time, relative to which the pulse of our technogenic civilization beats. Thanks to engineering tricks, the pulsed hydrogen masers that cool the cesium atoms in the stationary versions of NIST-F1 and NIST-F2 have been replaced with a conventional laser beam paired with a magneto-optical system. This made it possible to create compact and very stable external influences versions of the NIST-Fx standards capable of working in spacecraft. Rather figuratively named "Aerospace Cold Atom Clock", these frequency standards are installed in the satellites of navigation systems such as GPS, which provides them with amazing synchronization to solve the problem very exact calculation coordinates of GPS receivers used in our gadgets.

A compact version of the cesium fountain atomic clock called the "Aerospace Cold Atom Clock" is used in GPS satellites.

The calculation of the reference time is performed by an "ensemble" of ten NIST-F2s located in different research centers cooperating with NBS. The exact value of the atomic second is obtained collectively, and thus various errors and the influence of the human factor are eliminated.

However, it is possible that one day the cesium frequency standard will be perceived by our descendants as a very crude mechanism for measuring time, just as we now condescendingly look at the movements of the pendulum in the mechanical grandfather clocks of our ancestors.

A sensation has spread around the scientific world - time is evaporating from our Universe! So far, this is only a hypothesis of Spanish astrophysicists. But the fact that the flow of time on Earth and in space is different has already been proven by scientists. Time flows more slowly under the influence of gravity, accelerating as you move away from the planet. The task of synchronizing terrestrial and cosmic time is performed by hydrogen frequency standards, which are also called "atomic clocks".

First atomic time appeared along with the advent of astronautics, atomic clocks appeared in the mid-1920s. Now atomic clocks have become ordinary thing, each of us uses them every day: with their help, it works digital communications, GLONAS, navigation, transport.

Owners mobile phones one hardly thinks about how much complex work in space is carried out for tight time synchronization, and yet we are talking about only millionths of a second.

The exact time standard is stored in the Moscow region, in scientific institute physical-technical and radio-technical measurements. There are 450 such watches in the world.

The monopoly on atomic clocks is Russia and the United States, but in the United States clocks are based on cesium - radioactive metal, very harmful to the environment, and in Russia - based on hydrogen - a safer durable material.

This watch has no dial and hands: it looks like a big barrel made of rare and valuable metals, filled with the most advanced technologies - high-precision measuring instruments and equipment with atomic standards. The process of their creation is very long, complex and takes place in conditions of absolute sterility.

For 4 years, the clock installed on the Russian satellite has been studying dark energy. By human standards, they lose accuracy by 1 second in many millions of years.

Very soon, atomic clocks will be installed on Spektr-M - space observatory, which will see how stars and exoplanets form, look over the edge black hole at the center of our galaxy. According to scientists, due to the monstrous gravity, time flows here so slowly that it almost stops.

tvroscosmos

Often we 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.

The fact that the name contains the word "atomic" does not mean at all that the watch is a danger to life, even if thoughts about it immediately come to mind. atomic bomb or nuclear power plant. AT this case we're just talking about how the clock works. If in ordinary mechanical watch vibrational movements are made by gears and their movements are counted, then in atomic clocks vibrations of electrons inside atoms are counted. To better understand the principle of operation, let's recall the physics of elementary particles.

All substances in our world are made up of atoms. Atoms are made up 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 giving off energy, an electron can move from its energy level to a higher or lower one. An electron can receive energy from electromagnetic radiation by absorbing or emitting electromagnetic radiation of a certain frequency at each transition.

Most often there are watches in which atoms of the element Cesium -133 are used to change. If in 1 second the pendulum conventional watches commits 1 oscillating motion, then the electrons in atomic clocks based on Cesium-133, when moving 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, where there are not 60, but 9192631770 divisions, which are only 1 second. It is not surprising that atomic clocks are so accurate and have a number of advantages: atoms do not age, do not wear out, and the oscillation frequency will always be the same for one chemical element, thanks to which it is possible to simultaneously compare, for example, the readings of atomic clocks far in space and on Earth, not afraid of mistakes.

Thanks to atomic clocks, mankind in practice was able to test the correctness of the theory of relativity and make sure that, than on Earth. Atomic clocks are installed on many satellites and spacecraft, they are used for telecommunications needs, for mobile communications, they compare the exact time on the entire planet. Without exaggeration, it was thanks to the invention of the atomic clock 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.

Then the selected atoms pass through a magnetic field with a frequency close to 9192631770 Hz, which creates a quartz oscillator. Under the influence of the field, the cesium atoms change their energy states again, and fall on the detector, which fixes when the largest number falling 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, gets the number 1, which is the reference second.

So cesium atoms are used to check if the frequency is correct magnetic field generated by the crystal oscillator, helping to keep it constant.

It is interesting: although the atomic clocks that exist today are unprecedentedly accurate and can run without errors for millions of years, physicists are not going to stop there. Using atoms of various chemical elements, they are constantly working to improve the accuracy of atomic clocks. Of the latest inventions - atomic clocks on strontium, which are three times more accurate than their cesium counterpart. It would take them 15 billion years to be just a second behind – a time longer than the age of our universe…

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Atomic clocks are the most accurate time-measuring instruments in existence today, and are becoming increasingly popular. greater value with development and complication modern technologies.

Principle of operation

Atomic clocks do not keep accurate time thanks to radioactive decay, as it may seem from their name, 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. It doesn't quite match the usual clockwork. Atomic clocks are more reliable time keepers because their fluctuations do not change depending on such factors. environment like humidity, temperature or pressure.

The evolution of atomic clocks

Over the years, scientists have realized that atoms have resonant frequencies associated with the ability of each to absorb and emit electromagnetic radiation. In the 1930s and 1940s, high-frequency communications and radar equipment was developed that could interact with the resonance frequencies of atoms and molecules. This contributed to the idea of ​​the watch.

The first copies were built in 1949 National Institute standards and technologies (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 time accuracy 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 most stable atomic clock in the world was created in 1968 and was used as part of the NIST time reference system until the 1990s.

Improvement car

One of recent achievements in this area is laser cooling. This improved the signal-to-noise ratio and reduced the uncertainty in the clock signal. This cooling system and other equipment used to improve the cesium clock would require space the size of a railroad car to house it, although commercial options can fit in a suitcase. One of these laboratory installations keeps time in Boulder, Colorado, and is the most precise clock on the ground. They are only wrong by 2 nanoseconds per day, or 1 s in 1.4 million years.

Sophisticated technology

This tremendous accuracy is the result of complex technological process. First of all, 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 hole in the furnace. Electromagnets cause them to separate into separate beams with different energies. The required beam passes through the U-shaped hole, and the atoms are exposed to microwave energy at a frequency of 9.192.631.770 Hz. Due to this, they are excited and move into a different energy state. The magnetic field then filters out the other energy states of the atoms.

The detector responds to cesium and shows a maximum at correct meaning frequencies. This is necessary to set up the crystal oscillator that controls the clocking mechanism. Dividing its frequency by 9.192.631.770 gives one pulse per second.

Not only cesium

Although the most common atomic clocks use the properties of cesium, there are other types as well. They differ in the applied element and means of determining the change in energy level. Other materials are hydrogen and rubidium. Hydrogen atomic clocks function like 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 most simple and compact. In them, a glass cell filled with gaseous rubidium changes the absorption of light when exposed to microwave frequency.

Who needs accurate time?

Today, time can be counted with extreme precision, but why is this important? This is necessary in systems such as mobile phones, the Internet, GPS, aviation programs and digital television. At first glance, this is not obvious.

An example of how accurate time is used is packet synchronization. Through middle line communications go through thousands of phone calls. This is possible only because the conversation is not transmitted completely. The telecom company splits it into small packets and even skips some of the information. Then they pass through the line along with packets of other conversations and are restored at the other end without mixing. The telephone exchange clock 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 the 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, which leads to random fluctuations in the length of years and days. In the past, these changes would have gone unnoticed because timekeeping tools were too inaccurate. However, much to the dismay of researchers and scientists, the time of atomic clocks has to be adjusted to compensate for anomalies. real world. They are amazing tools for advancing modern technology, but their perfection is limited by the limits set by nature itself.

Firstly, the clock uses humanity as a means of program-time control.

Secondly, today the measurement of time is also the most accurate type of measurement of all conducted: the accuracy of time measurement is now determined by an incredibly error of the order of 1 10-11%, or 1 s in 300 thousand years.

And have achieved such accuracy modern people when they started using atoms, which, as a result of their oscillations, are the regulator of the atomic clock. Cesium atoms are in the two we need, energy states(+) and (-). Electromagnetic radiation with a frequency of 9 192 631 770 hertz is formed when the atoms move from the state (+) to (-), creating an accurate constant periodic process - the regulator of the atomic clock code.

In order for atomic clocks to work accurately, cesium must be evaporated in a furnace, as a result of which its atoms are ejected. Behind the furnace is a sorting magnet, which has the capacity of atoms in the (+) state, and in it, due to irradiation in a microwave field, the atoms go into the (-) state. The second magnet directs atoms that have changed state (+) to (-) to the receiving device. Many atoms that have changed their state are obtained only if the frequency of the microwave emitter coincides exactly with the frequency of vibrations of cesium 9 192 631 770 hertz. Otherwise, the number of atoms (-) in the receiver decreases.

Instruments constantly monitor and adjust the constancy of the frequency 9 192 631 770 hertz. So, the dream of watch designers came true, an absolutely constant periodic process was found: the frequency of 9,192,631,770 hertz, which regulates the course of atomic clocks.

Today, as a result international agreement, a second is defined as the radiation period multiplied by 9 192 631 770, corresponding to the transition between two hyperfine structural levels the ground state of the cesium atom (cesium-133 isotope).

To measure the exact time, you can also use vibrations of other atoms and molecules, such as atoms of calcium, rubidium, cesium, strontium, hydrogen molecules, iodine, methane, etc. However, the radiation of the cesium atom is recognized as the frequency standard. In order to compare the vibrations of different atoms with a standard (cesium), a titanium-sapphire laser was created that generates a wide frequency range in the range from 400 to 1000 nm.

The first creator of quartz and atomic clocks was an English experimental physicist Essen Lewis (1908-1997). In 1955, he created the first atomic frequency (time) standard on a beam of cesium atoms. As a result of this work, 3 years later (1958) a time service emerged based on the atomic frequency standard.

In the USSR, Academician Nikolai Gennadievich Basov put forward his ideas for creating atomic clocks.

So, atomic clock, one of exact types clock - a device for measuring time, where the natural oscillations of atoms or molecules are used as a pendulum. The stability of atomic clocks is the best among all existing types hours, which is a pledge highest precision. The atomic clock generator produces more than 32,768 pulses per second, unlike conventional clocks. Oscillations of atoms do not depend on air temperature, vibrations, humidity and many other external factors.

AT modern world When navigation is simply indispensable, atomic clocks have become indispensable helpers. They are able to locate spaceship, satellite, ballistic missile, aircraft, submarine, car automatically by satellite.

Thus, for the last 50 years, atomic clocks, or rather cesium clocks, have been considered the most accurate. They have long been used by timekeeping services, and time signals are also broadcast by some radio stations.

The atomic clock device includes 3 parts:

quantum Discriminator,

quartz oscillator,

electronics complex.

A quartz oscillator generates a frequency (5 or 10 MHz). The oscillator is an RC radio generator, in which the piezoelectric modes of a quartz crystal are used as a resonant element, where the atoms that have changed the state (+) to (-) are compared. To increase stability, its frequency is constantly compared with the oscillations of a quantum discriminator (atoms or molecules) . When a difference in oscillations appears, the electronics adjusts the frequency of the quartz oscillator to zero level, thereby improving the stability and accuracy of the clock to the desired level.

In the modern world, atomic clocks can be made in any country of the world for use in Everyday life. They are very small in size and beautiful. The size of the latest novelty of atomic clocks is not more than matchbox and their low power consumption - less than 1 Watt. And this is not the limit, perhaps in the future technical progress reaches mobile phones. In the meantime, compact atomic clocks are installed only on strategic missiles to increase the accuracy of navigation many times over.

Today, men's and women's atomic watches for every taste and budget can be bought in online stores.

In 2011, the world's smallest atomic clock was created by Symmetricom and the Sandia National Laboratory. This watch is 100 times more compact than previous commercially available versions. The size of an atomic chronometer is no larger than a matchbox. It needs 100 mW of power to operate, which is 100 times less than its predecessors.

It was possible to reduce the size of the watch by installing a mechanism that operates on the principle of determining the frequency instead of springs and gears. electromagnetic waves emitted by cesium atoms under the action of a laser beam of negligible power.

Such clocks are used in navigation, as well as in the work of miners, divers, where it is necessary to accurately synchronize time with colleagues on the surface, as well as accurate time services, because the error of atomic clocks is less than 0.000001 fractions of a second per day. The cost of the record-breaking small Symmetricom atomic clock was about $1,500.