Second-Scale ${}^9{\text{Be}}^{+}$ Spin Coherence in a Compact Penning Trap

Abstract

We report microwave spectroscopy of co-trapped ${}^9{\text{Be}}^{+}$ and ${}^{40}{\text{Ca}}^{+}$ within a compact permanent-magnet-based Penning ion trap. The trap is constructed with a reconfigurable array of NdFeB rings providing a 0.654 T magnetic field that is near the 0.6774-T magnetic-field-insensitive hyperfine transition in ${}^9{\text{Be}}^{+}$. Performing Ramsey spectroscopy on this hyperfine transition, we demonstrate nuclear spin coherence with a contrast decay time of >1 s. The ${}^9{\text{Be}}^{+}$ is sympathetically cooled by a Coulomb crystal of ${}^{40}{\text{Ca}}^{+}$, which minimizes ${}^9{\text{Be}}^{+}$ illumination and thus mitigates reactive loss. Introducing a unique high-magnetic-field optical detection scheme for ${}^{40}{\text{Ca}}^{+}$, we perform spin state readout without a 729~nm shelving laser. We record a fractional trap magnetic field instability below 20 ppb (<13 nT) at 43 s of averaging time with no magnetic shielding and only passive thermal isolation. We discuss potential applications of this compact, reconfigurable Penning trap.

6 pages, 4 figures

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Cited by in corpus (3)

• Rapid cooling of the in-plane motion of two-dimensional ion crystals in a Penning trap to millikelvin temperatures
• Absorption Spectroscopy of ${}^{40}$Ca Atomic Beams Produced via Pulsed Laser Ablation: A Quantitative Comparison of Ca and CaTiO${}_3$ Targets
• Adiabatic Cooling of Planar Motion in a Penning Trap Ion Crystal to Sub-Millikelvin Temperatures