Russian physicists from the Institute of Physics (Russian academy of sciences) work on a compact atomic clock of a new generation, and they have already created clock’s “heart” – a small quantum discriminator, which would allow new clock to be as accurate as one millionth part of a second per 24 hours.

Relative instability of one of the most accurate atomic standards of frequency and time in the world (cesium fountains) is as small as 10^-16. Such clocks measure time in national metrological laboratories. Clocks with lower accuracy 10^-13 provide time measurements at navigation satellites, GPS or GLONASS satellites, for instance. Most time measurements in our life do not need such extreme accuracy – 10^-11-10^-9 is enough. For example, currently produced precision quartz-controlled oscillators have relative long-term instability of 10^-10-10^-9 seconds per 24 hours. Traditional rubidium standards, which weigh up to several kilograms, show output frequency instability of 10^-12.

Russian physicists decided to combine in their clock small size and relative instability of 10^-11. “Pendulum” of this clock is cesium atom, in which nucleus-electron orientation changes about 10 billion times per second. Such clocks are expected to be largely used and to replace precision quartz-controlled oscillators, because they have better long-term stability, combined with smaller size and energy consumption. New clocks will be as small as 50 cm ³ and power demand of 0.3 Wt.

 

 

Previous generation of atomic clocks had size restrictions due to wavelength of resonance microwave field, which interacted with atomic environment. This fact made scientists think that creating clocks with dimensions less than several centimeters was impossible. However, discovery of coherent population trapping (CPT) in 1970s, and development of tiny diode lasers eliminated these restrictions. Now physicists use two optical fields, and do not need bulky microwave resonators.

Tiny lasers, used for optical excitation instead of gas-discharge lamps, allow minimizing size of atomic standards with relative instability of 10^-11 without performance degradation, and cutting energy consumption and costs. Such clocks can be embedded into various portable devices. Field of atomic clocks is a promising one – researchers in many countries are working on similar projects.

Russian physicists currently develop an electronic circuit of appropriate size and work on further reduction of size for a quantum discriminator, as well as on new technologies for building its main blocks. Development work will end by 2012, and after that a Russian company will start serial production of small and accurate domestic atomic clocks. Affordable device will allow significantly enhancing response of consumer navigation devices, developing jam-resistant broadband communication, introducing new detection techniques, and many more.

Source: Press-release of the Institute of Physics

Kizilova Anna