A cryogenic Paul trap for probing the nuclear isomeric excited state ${}^{229\text{m}}$Th${}^{3+}$

Abstract

While laser excitation of the nuclear isomeric transition in ${}^{229}$Th has been recently achieved for thorium atoms embedded in large-bandgap crystals, laser excitation and characterization of the nuclear transition in trapped ${}^{229}$Th${}^{3+}$ ions has not yet been accomplished. To address these experiments, a cryogenic Paul trap setup has been designed, built, and commissioned at LMU Munich. Here, we present the specifications of the new experimental platform and demonstrate its successful operation, showing the extraction, subsequent ion-guiding, mass-purification, and trapping of ${}^{229}$Th${}^{3+}$ and ${}^{229\text{m}}$Th${}^{3+}$ ions from a newly designed buffer-gas stopping cell as well as of ${}^{88}$Sr${}^{+}$ ions from laser ablation of a solid target. Further, we show sympathetic laser cooling of ${}^{229\text{(m)}}$Th${}^{3+}$ by Doppler-cooled ${}^{88}$Sr${}^{+}$ ions and the formation of mixed-species Coulomb crystals.

arXiv comment23 pages, 22 figures, raw data available from: https://zenodo.org/records/16691405

References in corpus (24)

• An ${}^{27}$Al${}^{+}$ quantum-logic clock with systematic uncertainty below $10^{-18}$
• Heating of trapped ions from the quantum ground state
• Frequency ratio of two optical clock transitions in ${}^{171}$Yb${}^{+}$ and constraints on the time-variation of fundamental constants
• A Single-Ion Nuclear Clock for Metrology at the 19th Decimal Place
• Direct detection of the 229Th nuclear clock transition
• Enhanced effect of temporal variation of the fine structure constant in diatomic molecules
• A clock with $8\times 10^{-19}$ systematic uncertainty
• Frequency ratio of the ${}^{229\mathrm{m}}$Th nuclear isomeric transition and the ${}^{87}$Sr atomic clock
• Laser spectroscopic characterization of the nuclear clock isomer ${}^{229m}$Th
• Cryogenic Trapped-Ion System for Large Scale Quantum Simulation
• Observation of the radiative decay of the ${}^{229}\mathrm{Th}$ nuclear clock isomer
• A proposed experimental method to determine $\alpha$-sensitivity of splitting between ground and 7.6 eV isomeric states in Th-229
• Fabrication and heating rate study of microscopic surface electrode ion traps
• Radiative lifetime and energy of the low-energy isomeric level in ${}^{229}$Th
• PENTATRAP: A novel cryogenic multi-Penning trap experiment for high-precision mass measurements on highly charged ions
• Closed-cycle, low-vibration 4 K cryostat for ion traps and other applications
• A cryogenic radio-frequency ion trap for quantum logic spectroscopy of highly charged ions
• ${}^{229}{\mathrm{ThF}}_4$ thin films for solid-state nuclear clocks
• Controlling ${}^{229}$Th isomeric state population in a VUV transparent crystal
• Ultra-low vibration closed-cycle cryogenic surface-electrode ion trap apparatus
• Determination of the extraction efficiency for ${}^{233}$U source $\alpha$-recoil ions from the MLL buffer-gas stopping cell
• Long-term drifts of stray electric fields in a Paul trap
• Towards a 229Th-based nuclear clock
• Sympathetic cooling of trapped Th3+ alpha-recoil ions for laser spectroscopy