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arXiv · 2311.13736

Multi-ion frequency reference using dynamical decoupling

Lennart Pelzer·Kai Dietze·Víctor J. Martínez-Lahuerta·Ludwig Krinner·Johannes Kramer·Fabian Dawel·Nicolas C. H. Spethmann·Klemens Hammerer·Piet O. Schmidt
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Abstract

We present the experimental realization of a continuous dynamical decoupling scheme which suppresses leading frequency shifts in a multi-ion frequency reference based on $^{40}\mathrm{Ca}^+$. By near-resonant magnetic coupling of the $^2\mathrm{S}_{1/2}$ and $^2\mathrm{D}_{5/2}$ Zeeman sub-levels using radio-frequency dressing fields, engineered transitions with reduced sensitivity to magnetic-field fluctuations are obtained. A second stage detuned dressing field reduces the influence of amplitude noise in the first stage driving fields and decreases 2\textsuperscript{nd}-rank tensor shifts, such as the electric quadrupole shift. Suppression of the quadratic dependence of the quadrupole shift to $3(2)\,\text{mHz}/μm^2$ and coherence times of $290(20)\,\text{ms}$ on the optical transition are demonstrated even within a laboratory environment with significant magnetic field noise. Besides removing inhomogeneous line shifts in multi-ion clocks, the demonstrated dynamical decoupling technique may find applications in quantum computing and simulation with trapped ions by a tailored design of decoherence-free subspaces.

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Lennart Pelzer, Kai Dietze, Víctor J. Martínez-Lahuerta, Ludwig Krinner, Johannes Kramer, Fabian Dawel, Nicolas C. H. Spethmann, Klemens Hammerer, Piet O. Schmidt. 2023-11-22. Multi-ion frequency reference using dynamical decoupling. https://arxiv.org/abs/2311.13736

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