Yttrium ion as a platform for quantum information processing

TL;DR

This paper explores the potential of singly-ionized yttrium ($^{89} ext{Y}^+$) as a promising platform for quantum information processing, highlighting its unique features and detailed spectroscopic analysis.

Contribution

It provides the first high-resolution spectroscopy and comprehensive electronic structure calculations for $^{89} ext{Y}^+$, demonstrating its suitability for quantum computing applications.

Findings

Measured hyperfine structure of low-lying levels.

Calculated lifetimes, transition matrix elements, hyperfine coefficients.

Analyzed schemes for qubit operations and error mitigation.

Abstract

Engineering large-scale quantum computers which simultaneously provide high-fidelity quantum operations, low memory errors, low crosstalk, and reasonable resource usage remains an outstanding challenge across quantum computing platforms. In trapped ions, progress has largely focused on alkaline-earth and ytterbium ions, whose simple electronic structures facilitate control over their internal state. Here we investigate singly-ionized yttrium ($^{89}\mathrm{Y}^+$), a two-valence-electron ion whose ground-state manifold hosts a nuclear-spin qubit and which also features a variety of low-lying metastable manifolds, for applications in quantum information processing. Because experimental data are limited, we perform high-resolution laser-induced fluorescence spectroscopy to measure the hyperfine structure of several low-lying levels, and carry out comprehensive electronic structure calculations to determine lifetimes, transition matrix elements, and hyperfine coefficients for manifolds addressable with visible, near-visible, or infrared wavelengths. Using these results, we analyze schemes for qubit storage, initialization, readout, leakage mitigation, and single- and two-qubit gates. These results position $^{89}\mathrm{Y}^+$ as a uniquely capable next-generation trapped-ion qubit, combining field-insensitive nuclear-spin or clock-qubit storage with spectrally isolated transitions for operations.