How an Atomic Clock Works
Atomic clocks are used for thousands of applications all over the world. From controlling satellites to even synchronising a computer network using a NTP server, atomic clocks have changed the way we control and govern time.
In terms of accuracy an atomic clock is unrivalled. Digital quartz clocks may keep accurate time for a week, not losing more than a second but an atomic clock can keep time for millions of years without drifting as much.
Atomic clocks work on the principle of quantum leaps, a branch of quantum mechanics which states that an electron; a negatively charged particle, will orbit a nucleus of an atom (the centre) in a certain plain or level. When it absorbs or releases enough energy, in the form of electromagnetic radiation, the electron will jump to a different plane – the quantum leap.
By measuring the frequency of the electromagnetic radiation corresponding to the transition between the two levels, the passage of time can be recorded. Caesium atoms (caesium 133) are preferred for timing as they have 9,192,631,770 cycles of radiation in every second. Because the energy levels of the caesium atom (the quantum standards) are always the same and is such a high number, the caesium atomic clock is incredibly precise.
The most common form of atomic clock used in the world today is the caesium fountain. In this type of clock a cloud of atoms is projected up into a microwave chamber and allowed to fall down under gravity. Laser beams slow these atoms down and the transition between the atom’s energy levels are measured.
The next generation of atomic clocks are being developed use ion traps rather than a fountain. Ions are positively charged atoms which can be trapped by a magnetic field. Other elements such as strontium are being used in these next generation clocks and it is estimated that the potential accuracy of a strontium ion trap clock could be 1000 times that of the current atomic clocks.
Atomic clocks are utilised by all sorts of technologies; satellite communication, the Global Positioning System and even Internet trading is reliant on atomic clocks. Most computers synchronise indirectly to an atomic clock by using a NTP server. These devices receive the time from an atomic clock and distribute around their networks ensuring precise time on all devices.
