1000th issue of Uspekhi Fizicheskikh Nauk journal: Accurate frequency and time dissemination in the optical domain. (February 2018)

• Record Type: Journal Article
• Authors: Khabarova, K Yu; Kalganova, E S; Kolachevsky, N N
• Is Part Of: Physics Uspekhi. Volume 61:Number 2(2018:Feb.)
• Page Start: 203
• Page End: 211
• Publication Date: 2018-02
• Subjects: fiber links -- optical frequency and time dissemination -- femtosecond lasers -- erbium doped lasers -- frequency stabilization; 06.20.Jr -- 06.30.Ft -- 12.20.Fv -- 32.10.Fn -- 32.30.Jc -- 42.62.Fi; Physics -- Periodicals; 530.05
• DOI: 10.3367/UFNe.2017.05.038131
• Languages: English
• ISSNs: 1063-7869

Abstract

Abstract: The development of the optical frequency comb technique has enabled a wide use of atomic optical clocks by allowing frequency conversion from the optical to the radio frequency range. Today, the fractional instability of such clocks has reached the record eighteen-digit level, two orders of magnitude better than for cesium fountains representing the primary frequency standard. This is paralleled by the development of techniques for transferring accurate time and optical frequency signals, including fiber links. With this technology, the fractional instability of transferred frequency can be lowered to below 10 −18 with an averaging time of 1000 s for a 1000 km optical link. At a distance of 500 km, a time signal uncertainty of 250 ps has been achieved. Optical links allow comparing optical clocks and creating a synchronized time and frequency standard network at a new level of precision. Prospects for solving new problems arise, including the determination of the gravitational potential, the measurement of the continental Sagnac effect, and precise tests of fundamental theories.