In the future, it is planned to disseminate this light also within a European network. With a linewidth of only 10 mHz, the laser that researchers from the Physikalisch-Technische Bundesanstalt (PTB) have now developed together with US researchers from JILA, a joint institute of the National Institute of Standards and Technology (NIST) and the University of Colorado, Boulder, has established a new world record. For researchers, this is a measure for the light wave&China led Tri proof lights39;s regular frequency and linewidth. The thermal noise of the silicon body is so low that the length fluctuations observed only originate from the thermal noise of the dielectric SiO2/Ta2O5 mirror layers. Within the scope of a nearly 10-year-long joint project with the US colleagues from JILA in Boulder, Colorado, a laser has now been developed at PTB whose linewidth is only 10 mHz (0. With novel crystalline mirror layers and lower temperatures, the disturbing thermal noise can be further reduced. The results have been published in the current issue of "Physical Review Letters".

"The smaller the linewidth of the laser, the more accurate the measurement of the atom's frequency in an optical clock. Lasers have brought about a real revolution in many fields of research and in metrology – or even made some new fields possible in the first place. More than 50 years have passed since the first technical realization of the laser, and we cannot imagine how we could live without them today. Similar to an organ pipe, the resonator length determines the frequency of the wave which begins to oscillate, i.Lasers were once deemed a solution without problems – but that is now history. At PTB, the ultrastable light from these lasers is already being distributed via optical waveguides and is then used by the optical clocks in Braunschweig. This length corresponds to nearly ten times the distance between the Earth and the moon. Although the mirror layers are only a few micrometers thick, they dominate the resonator's length stability., the light wave inside the resonator. Its extent depends on the materials used to build the resonator as well as on the resonator's temperature.

This precision is useful for various applications such as optical atomic clocks, precision spectroscopy, radioastronomy and for testing the theory of relativity. In total, the resonator length, however, only fluctuates in the range of 10 attometers.01 Hz), hereby establishing a new world record. 3. The linewidth could then even become smaller than 1 mHz.In addition to the new laser’s extremely small linewidth, Legero and his colleagues found out by means of measurements that the emitted laser light's frequency was more precise than what had ever been achieved before.The scientists at PTB had to isolate the resonator nearly perfectly from all environmental influences which might change its length.The core piece of each of the lasers is a 21-cm long Fabry-Pérot silicon resonator. The resonator consists # of two highly reflecting mirrors which are located opposite each other and are kept at a fixed distance by means of a double cone. This plan would allow even more precise comparisons between the optical clocks in Braunschweig and the clocks of our European colleagues in Paris and London", Legero says.