Have you ever noticed that your clock in the house shows different times? And how do you know which of all the options is correct? We will learn the answers to all these questions by thoroughly studying the operating principle of atomic clocks.

Atomic clock: description and principle of operation

Let's first understand what the atomic clock mechanism is. An atomic clock is a device with which time is measured, but it uses its own oscillations as the periodicity of the process, and also everything happens on the atomic and molecular level. Hence such precision.

It is safe to say that atomic clocks are the most accurate! It is thanks to them that the Internet and GPS navigation function in the world; we know the exact location of the planets in solar system. The error of this device is so minimal that we can confidently say that they are world class! Thanks to the atomic clock, the entire world synchronization occurs; it is known where certain changes are located.

Who invented, who created, and also who came up with this miracle watch?

Back in the early forties of the twentieth century, it was known about the atomic beam magnetic resonance. At first, its application had nothing to do with watches - it was only a theory. But already in 1945, Isidor Rabi proposed creating a device, the concept of which was that they would work based on the technique described above. But they were designed in such a way that they did not show accurate results. And already in 1949, the National Bureau of Standards notified the whole world about the creation of the first atomic clock, which was based on molecular compounds of ammonia, and already in 1952, technologies were mastered to create a prototype based on cesium atoms.

Having heard about ammonia and cesium atoms, the question arises: is this wonderful clock radioactive? The answer is clear - no! There is no atomic decay in them.

Nowadays, there are many materials from which atomic clocks are made. For example, this is silicon, quartz, aluminum and even silver.

How does the device work?

Let's figure out what a atomic energy clock looks like and how it works. To do this, we offer a description of their work:

For the correct functioning of this particular clock, neither a pendulum nor a quartz oscillator is needed. They use signals that arise from the quantum transition of a single electron between two energy levels of an atom. As a result, we are able to observe an electromagnetic wave. In other words, we get frequent fluctuations and an ultra-high level of system stability. Every year, due to new discoveries, processes are modernized. Not long ago, specialists from The National Institute of Standards and Technology (NIST) became record holders, setting an absolute world record. They were able to bring the accuracy of the atomic clock (based on strontium) to the very minimum deviation, namely: in 15 billion years one second ticks by. Yes, yes, you didn’t think so, this is exactly the age currently assigned to our Universe. This is a colossal discovery! After all, it was strontium that played vital role in this record. An analogue of the “tick” was the moving strontium atoms in its spatial lattice, which was created by scientists using a laser. As always in science, in theory everything seems enchanting and already improved, but the instability of such a system may turn out to be less joyful in practice. It is precisely because of its instability that the cesium device has gained worldwide popularity.

Now let's look at what such a device consists of. The main details here are:

• quantum discriminator;
• quartz generator;
• electronics.

A quartz generator is similar to a self-oscillator, but to produce resonant element, it uses piezoelectric modes of a quartz crystal.

Having a quantum discriminator and a quartz oscillator, under the influence of their frequency, they are compared and when a difference is detected, the feedback circuit requires the quartz oscillator to adjust to the required value and increase stability and accuracy. As a result, at the output we see on the dial exact value, which means exact time.

Early models had quite large sizes, however, in October 2013, the Bathys Hawaii company made a splash by releasing a miniature atomic wristwatch. At first everyone took this statement as a joke, but it soon became clear that it was indeed true, and they operate on the basis of a Cesium 133 atomic source. The safety of the device is ensured by the fact that What radioactive element contained in the form of gas in a special capsule. Photos of this device spread all over the world.

Many people in the topic of atomic clocks are interested in the issue of power source. A lithium-ion battery is used as a battery. But alas, it is not yet known how long such a battery will last.

BathysHawaii's clocks were truly the first atomic ones. wristwatch. Previously, there were already known cases of the release of a relatively portable device, but, unfortunately, it did not have an atomic power source, but only synchronized with a real dimensional clock via wireless radio. It is also worth mentioning the cost of such a gadget. The pleasure was valued at 12 thousand US dollars. It was clear that at such a price the watch would not gain wide popularity, but the company did not strive for this, because it released it in a very limited batch.

We know of several types of atomic clocks. There are no significant differences in their design and principles, but there are still some differences. So, the main ones are the means of finding changes and their elements. You can select following types hours:

1. Hydrogen. Their essence lies in the fact that hydrogen atoms are supported at the required energy level, but the walls are made of a special material. Based on this, we conclude that it is hydrogen atoms that very quickly lose their energy state.
2. Cesium. They are based on cesium beams. It is worth noting that these watches are the most accurate.
3. Rubidium. They are the simplest and very compact.

As mentioned earlier, atomic clocks are a very expensive gadget. Thus, the Hoptroff pocket watch No. 10 is a bright representative of a new generation of toys. The price of such a stylish and very precise accessory is 78 thousand dollars. Only 12 copies were produced. The mechanism of this device uses a high-frequency oscillating system, which is also equipped with a GPS signal.

The company did not stop there, and in its tenth version of the watch it wants to use the method of placing the mechanism in a gold case, which will be printed on a popular 3D printer. It has not yet been calculated exactly how much gold will be used for this version of the case, but the estimated retail price of this masterpiece is already known - it was about 50 thousand pounds sterling. And this is not the final price, although it takes into account all the volumes of research, as well as the novelty and uniqueness of the gadget itself.

Historical facts about the use of watches

How can we talk about atomic clocks without mentioning the most interesting facts, which are associated with them and time in general:

1. Did you know that in ancient Egypt the oldest sundial ever found?
2. The error of atomic clocks is minimal - it is only 1 second per 6 million years.
3. Everyone knows that there are 60 seconds in a minute. But few people delved into how many milliseconds are in one second? And there are not many and not few of them - a thousand!
4. Every tourist who was able to visit London always wanted to see Big Ben with his own eyes. But unfortunately, not many people know that Big Ben is not a tower at all, but the name of a huge bell that weighs 13 tons and rings inside the tower.
5. Have you ever wondered why the hands of our clocks go from left to right or, as we used to say, “clockwise”? This fact is directly related to the way the shadow moves on a sundial.
6. The very first wristwatches were invented back in 1812. They were made by the founder of Breguet for the Queen of Neapolitan.
7. Before the First World War, wristwatches were considered only a women's accessory, but soon, due to their convenience, they were also chosen by the male part of the population.

These are devices for measuring time, the operating principle of which is based on atomic physics. Due to the properties of the chemical elements used in the design, the error of these watches is minimal. For example, devices based on thorium-229 will lag by a tenth of a second in about 14 billion years.

How do atomic clocks work?

If in quartz watches the reference frequency for determining the second is the number of vibrations of a quartz crystal, then in atomic watches it is taken to be the frequency of electron transitions in the atoms of certain chemical elements from one energy level to another.

1 - Electronic component (chip)

2 - Nuclear source

3 - Photodetector

4 - Upper heater

5 - Resonant cell

6 - Wave plate

7 - Bottom heater

8 - Vertical emitting laser

Here's the point: atoms have electrons. They have energy. When absorbing or releasing energy, electrons jump from one energy level to another, absorbing or emitting electromagnetic waves, the frequency of which is always the same. This phenomenon can be controlled: when an atom is exposed to microwave radiation, it responds with a certain number of vibrations.

This property is used to improve the accuracy of time measurements. Thus, it is recognized that a second is the duration of 9192631770 radiation cycles. This frequency corresponds to a transition between two energy levels of the cesium-133 atom. By comparing the oscillation frequency of a quartz oscillator with the transition frequency of the element’s atoms, the slightest deviations are recorded. If there are deviations, the quartz vibrations are adjusted.

Cesium is not the only material used in atomic clocks. Devices based on chemical elements are appearing that can provide even greater precision: ytterbium, thorium-229, strontium.

Why are atomic clocks accurate?

Oscillation frequency chemical element is the same, and this minimizes the possibility of error. In addition, unlike a quartz crystal, the atoms do not wear out or lose their chemical properties over time.

Other names for atomic clocks: quantum, molecular.

Firstly, mankind uses clocks as a means of program-time control.

Secondly, nowadays the measurement of time is the most exact view of all measurements carried out: the accuracy of time measurement is now determined by an incredible error of the order of 1·10-11%, or 1 s in 300 thousand years.

And we 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 found in the two we need, energy states(+) and (-). Electromagnetic radiation with a frequency of 9,192,631,770 hertz is produced when atoms change from the (+) state to the (-) state, creating a precise, 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, a process that releases its atoms. Behind the furnace there is a sorting magnet, which has the capacity of atoms in the (+) state, and in it, due to irradiation in the microwave field, the atoms go into the (-) state. The second magnet directs the atoms that have changed state (+) to (-) into the receiving device. Many atoms that have changed their state are obtained only if the frequency of the microwave emitter exactly coincides with the cesium vibration frequency of 9,192,631,770 hertz. Otherwise, the number of atoms (-) in the receiving device decreases.

The devices constantly monitor and regulate the constant frequency of 9,192,631,770 hertz. This means that the dream of watch designers has come true, an absolutely constant periodic process has been found: a frequency of 9,192,631,770 hertz, which regulates the course of atomic clocks.

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

To measure precise 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 different atoms With the standard (cesium), a titanium-sapphire laser was created, generating a wide range of frequencies 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 using a beam of cesium atoms. As a result of this work, 3 years later (1958) a time service based on the atomic frequency standard arose.

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

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

IN modern world When you simply cannot do without navigation, atomic clocks have become indispensable assistants. They are able to determine the location spaceship, satellite, ballistic missile, airplane, submarine, car automatically via satellite communication.

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

The atomic clock device includes 3 parts:

quantum discriminator,

quartz oscillator,

electronics complex.

The quartz oscillator generates a frequency (5 or 10 MHz). The oscillator is an RC radio generator, which uses piezoelectric modes of a quartz crystal as a resonant element, where atoms that have changed 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 increasing the stability and accuracy of the watch to the desired level.

In the modern world, atomic clocks can be manufactured in any country in the world for use in everyday life. They are very small in size and beautiful. The size of the latest new atomic clock is no more than matchbox and their low power consumption - less than 1 Watt. And this is not the limit, perhaps in the future technical progress will reach mobile phones. In the meantime, compact atomic clocks are installed only on strategic missiles to increase navigation accuracy 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 specialists from Symmetricom and Sandia National Laboratories. This watch is 100 times more compact than previous commercially available versions. The size of an atomic chronometer is no larger than a matchbox. To operate, it only needs 100 mW of power - this is 100 times less compared to its predecessors.

It was possible to reduce the size of the watch by installing instead of springs and gears a mechanism operating on the principle of determining frequency electromagnetic waves, emitted by cesium atoms under the influence 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 precise time services, because the error of atomic clocks is less than 0.000001 fractions of a second per day. The cost of the record small atomic clock Symmetricom was about $1,500.

Highly accurate atomic clocks that make an error of one second every 300 million years. This clock, which replaced an older model that had an error of one second every 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 most simple watch are probably solar: for their operation, only the Sun and an object that casts a shadow are needed. The disadvantages of this method of determining time are obvious. Water and hourglass are also no better: they are suitable only for measuring relatively short periods of time.

The most ancient mechanical watch 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 Christiaan 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 this 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 oscillatory systems in devices. Introduced in 1927 by Bell Labs employees quartz watch used piezoelectric properties quartz crystal: when exposed to it 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 ​​using atomic vibrations Hydrogen for measuring 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 the discoverer of nuclear magnetic resonance, Isidor Rabi, began working on atomic clock with cesium-133, but the outbreak of war prevented him. After the war in 1949, the first US National Standards Committee was created with the participation of Harold Lyonson. molecular clock using ammonia molecules. 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 widened. This effect is very similar to friction in a mechanical watch.

Later, in 1955, Louis Essen of the National physical laboratory Great Britain introduced the first atomic clock using cesium-133. 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 electromagnetic radiation there are their own 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 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 ensures the heating of cesium gas, as a result of which its atoms begin to move from one energy level to 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.

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 are widely used in navigation, space industry, to determine the location of satellites, in military sphere,for 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 you take cosmic distances. For example, let's take American system GPS navigation, when using conventional electronic watch, the coordinate measurement error will be quite significant, which can affect all other calculations, and this can lead to consequences if we're talking about about 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 with a 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 based 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 the international atomic time. But in the kingdom there are not the most accurate watch on Earth.

most accurate atomic clock photo

The United States announced that it had developed an experimental type of precise clock based on cesium atoms; its 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.