Measuring the gravitational frequency shift in a hydrogen clock when transmitting a signal via optical and radio frequency communication channels

A scheme for measuring the gravitational frequency shift of hydrogen clocks during their movement between two points located at different orthometric altidudes with simultaneous signal transmission via radio and fiber-optic communication lines has been implemented. Practical interest in studying the gravitational frequency shift of quantum standards is associated with the need to take it into account to improve accuracy in navigation satellite systems. Such measurements were performed using a space synchronization channel using signals from global navigation satellite systems. This became especially relevant when improving the metrological characteristics of quantum frequency and time standards, in particular, using transportable clocks based on optical lattices when transmitting a signal via fiber-optic communication lines. On the other hand, using quantum clocks, measurements of the difference in orthometric heights are performed using the relativistic synchronization method and the simultaneous use of the frequency standard redshift effect due to time dilation in a gravitational field and the redshift effect of photons overcoming the gravitational field. This paper presents the results of measuring the gravitational frequency shift of a hydrogen clock when it is moved between two points located at different orthometric heights with signal transmission via a fiber-optic communication line and via a radio channel. In the first case, the radiation of a diode laser at a wavelength of 1.5 μm amplitude-modulated by a signal from the transported hydrogen clock at a frequency of 10 MHz, was transmitted via a fiber-optic communication line when a stationary hydrogen clock was used as a reference. Transmission via a radio channel was carried out via a coaxial radio frequency cable. The measurements were carried out on the territory of the West Siberian branch of the FSUE "VNIIFTRI".