Nuclear coherent population transfer to the $^{229m}$Th isomer using x-ray pulses

TL;DR

This paper explores theoretical methods for populating the $^{229m}$Th nuclear isomer using coherent x-ray pulses, comparing schemes like STIRAP and $\pi$ pulses across different experimental setups.

Contribution

It introduces the application of quantum optics techniques to nuclear state manipulation and identifies the Gamma Factory as the most promising experimental platform.

Findings

Gamma Factory setup is most promising for isomer population.

Theoretical transition probabilities are provided and discussed.

Numerical simulations demonstrate feasibility of population transfer schemes.

Abstract

Population of the 8 eV $^{229m}$Th isomer via the second nuclear excited state at 29.19 keV by means of coherent x-ray pulses is investigated theoretically. We focus on two nuclear coherent population transfer schemes using partially overlapping x-ray pulses known from quantum optics: stimulated Raman adiabatic passage (STIRAP), and successive $\pi$ pulses. Numerical results are presented for three possible experimental setups. Our results identify the Gamma Factory as the most promising scenario, where two ultraviolet pulses combined with relativistically accelerated ions deliver the required intensities for efficient isomer population. Our simulations require knowledge of the in-band and cross-band nuclear transition probabilities. We give theoretically predicted values for the latter and discuss them in the context of recent experiments.