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arXiv · 2609.10725

Narrow-line magneto-optical trap of titanium atoms

Rowan Duim·Scott Eustice·Jackson Schrott·Hiromitsu Sawaoka·Dan M. Stamper-Kurn
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Abstract

We realize narrow-linewidth magneto-optical traps of $^{46}$Ti, $^{48}$Ti and $^{50}$Ti atoms based on a 1040 nm-wavelength transition, cooling atoms to a minimum temperature in one dimension of $T_z=990(20)$ nK and a three-dimensional temperature of $T_\mathrm{3D}=1.28(7)$ $μ$K. Atoms are pre-cooled in a broad-line magneto-optical trap and then transferred with about 25% efficiency to the narrow-line trap. We operate the narrow-line trap in two stages over 85 ms. First, a single cooling beam, blue-detuned from the narrow-linewidth atomic resonance, optically pumps and traps the atoms on a two-dimensional surface where the Zeeman shift from the applied spherical quadrupole magnetic field brings the light nearly to resonance. Second, four additional beams, counter-propagating in the transverse directions, cool and compress the atoms in all dimensions. The high magnetic moment of the laser cooling state makes the dynamics of the narrow-line titanium trap similar to those of other magnetic atoms. We measure the lifetime of the excited state of the transition to be $τ=8.2(9)$ $μ$s, indicating a transition linewidth of $γ/2π=20(2)$ kHz, and also measure isotope shifts on the narrow-line transition. We use Stern-Gerlach separation on the ultracold Ti gas to measure the $m_J$-distribution in the narrow-line magneto-optical trap, finding over 98% of the atoms in the stretched spin state.

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Rowan Duim, Scott Eustice, Jackson Schrott, Hiromitsu Sawaoka, Dan M. Stamper-Kurn. 2026-09-09. Narrow-line magneto-optical trap of titanium atoms. https://arxiv.org/abs/2609.10725

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