Performance of a 229 Thorium solid-state nuclear clock

TL;DR

This paper explores the development of a solid-state nuclear clock using Thorium nuclei in Calcium fluoride, analyzing its potential stability and limitations at low temperatures for ultra-precise timekeeping.

Contribution

It introduces a novel solid-state nuclear clock concept with specific analysis of crystal effects and proposes a photon counting stabilization method for enhanced stability.

Findings

Potential fractional instability of 10^{-19}

Decoherence limits at liquid Nitrogen temperatures

Proposed photon counting stabilization method

Abstract

The 7.8 eV nuclear isomer transition in 229 Thorium has been suggested as an etalon transition in a new type of optical frequency standard. Here we discuss the construction of a "solid-state nuclear clock" from Thorium nuclei implanted into single crystals transparent in the vacuum ultraviolet range. We investigate crystal-induced line shifts and broadening effects for the specific system of Calcium fluoride. At liquid Nitrogen temperatures, the clock performance will be limited by decoherence due to magnetic coupling of the Thorium nucleus to neighboring nuclear moments, ruling out the commonly used Rabi or Ramsey interrogation schemes. We propose a clock stabilization based on counting of flourescence photons and present optimized operation parameters. Taking advantage of the high number of quantum oscillators under continuous interrogation, a fractional instability level of 10^{-19} might be reached within the solid-state approach.