On possible ways for future redefinition of the SI time unit

TL;DR

This paper explores future redefinition options for the SI second, focusing on optical and nuclear frequency standards, and analyzes constants relevant to redefining units of time, mass, and electric current.

Contribution

It provides a comprehensive analysis of potential future standards for redefining the SI second using optical, thorium, and super-high frequency standards.

Findings

Optical frequency standards offer promising accuracy improvements.

Constants related to time, mass, and electric current are evaluated for redefinition.

Multiple pathways for future SI unit redefinition are discussed.

Abstract

The current methods for realization of the second with the highest accuracy through the frequency of the hyperfine transition between two levels of the ground state of the cesium 133 atom are considered. It is discussed possible ways for the future redefinition of the SI time unit with the help of optical frequency standards, as well as thorium and super-high frequency standards. Several constants which can be also used for definitions of the time, mass and electric current units are analyzed.