Measurement of the dynamic polarizability of Dy atoms near the 626-nm intercombination line

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Measurement of the dynamic polarizability of Dy atoms near the 626-nm intercombination line

Marian Kreyer, Jeong Ho Han, Cornelis Ravensbergen, Vincent Corre, Elisa Soave, Emil Kirilov, and Rudolf Grimm

Phys. Rev. A 104, 033106 – Published 10 September 2021

Abstract

We report on measurements of the anisotropic dynamical polarizability of Dy near the 626-nm intercombination line, employing modulation spectroscopy in a one-dimensional optical lattice. To eliminate large systematic uncertainties resulting from the limited knowledge of the spatial intensity distribution, we use K as a reference species with accurately known polarizability. This method can be applied independently of the sign of the polarizability, i.e., for both attractive and repulsive optical fields on both sides of a resonance. By variation of the laser polarization we extract the scalar and the tensorial part. To characterize the strength of the transition, we also derive the natural linewidth. We find our result to be in excellent agreement with literature values, which provide a sensitive benchmark for the accuracy of our method. In addition we demonstrate optical dipole trapping on the intercombination line, confirming the expected long lifetimes and low heating rates. This provides an additional tool to tailor optical potentials for Dy atoms and for the species-specific manipulation of atoms in the Dy-K mixture.

Received 22 March 2021
Accepted 17 August 2021

DOI:https://doi.org/10.1103/PhysRevA.104.033106

Physics Subject Headings (PhySH)

Cold gases in optical lattices Cooling & trapping Electronic transitions Fermi gases Lifetimes & widths Mixtures of atomic and/or molecular quantum gases Optical lattices & traps

Atomic, Molecular & Optical

Authors & Affiliations

Marian Kreyer ¹, Jeong Ho Han ^1,2,*, Cornelis Ravensbergen ¹, Vincent Corre ^1,2, Elisa Soave¹, Emil Kirilov ^1,2, and Rudolf Grimm ^1,2

¹Institut für Experimentalphysik and Forschungszentrum für Quantenphysik, Universität Innsbruck, 6020 Innsbruck, Austria
²Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria

^*Present address: Korea Research Institute of Standards and Science, Daejeon 34113, South Korea.

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Vol. 104, Iss. 3 — September 2021

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Images

Figure 1
(a) Schematic of our experiment. The 1D optical lattice beam (OL) is overlapped by the optical dipole trap (ODT) and imaging beam at the sample position. The second beam of the crossed dipole trap propagates along the $z$ direction (direction of gravity) and is not shown here. The external magnetic field $\vec{B}$ is aligned with the gravity axis, defining the polarization angle $θ$ for the $\vec{E}$ field of the lattice beam. $θ$ can be changed by rotating a half-wave plate. (b) and (c) Band structures of an optical lattice for Dy and K with a typical depth of $V_{Dy} = 30 E_{r, Dy}$ and $V_{K} = 5 E_{r, K}$ , respectively. Atoms are transferred if the photon energy $h ν$ from the modulation matches the energy difference between bands at a given quasimomentum $q$ .
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Figure 2
Representative amplitude-modulation spectra for an optical lattice at $λ = 626.174$ nm. The atomic cloud size is plotted as a function of the modulation frequency. (a) For ${}^{161}{Dy}$ , at a power $P = 33.5$ mW, we obtain a lattice depth of ${\hat{V}}_{Dy} = 28.96 (9) E_{r, Dy}$ by matching $ν_{0} - Δ ν$ , extracted from a Gaussian fit (solid line), to the band gap. (b) For ${}^{40}K$ the spectrum, taken at $P = 67$ mw, shows an asymmetric profile due to the broad band structure. We take into account systematic errors in the numerical simulation used to determine the lattice depth. The fitted simulation (solid line) yields a depth of ${\hat{V}}_{K} = 4.70 (14) E_{r, K}$ , which is consistent with the depth of ${\hat{V}}_{K} = 4.73 (8) E_{r, K}$ obtained from an arctangent fit (dashed line). The errors given here represent the statistical fitting errors. The systematic errors are much larger (see text).
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Figure 3
Measurements of anisotropic polarizability for ${}^{161}{Dy}$ . (a) Angle dependence of the polarizability at $λ = 625.884$ nm. The variation reveals the scalar and tensor contributions. The solid line shows a fit according to Eq. (4). (b) Wavelength dependence of the dynamical polarizability of ${}^{161}{Dy}$ near the intercombination transition line for two different polarization angles $θ = 0, π / 2$ (parallel and perpendicular to the quantization axis). The dashed line indicates the resonance center. In (a) the error bars represent the $1 σ$ statistical fitting errors from the individual spectra used to determine the lattice depth. In (b) the error bars are smaller than the symbol size.
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Figure 4
Measured (a) scalar and (b) tensor components of the dynamical polarizability of ${}^{161}{Dy}$ near the 626-nm line. Solid lines show a fit according to Eq. (5). Error bars are smaller than the symbol size.
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Figure 5
Time evolution of temperature and atom number in a bichromatic crossed dipole trap. (a) Temperature in the $x$ and $y$ directions with linear fits for the first 1 s (dashed vertical line). (b) Atom number and corresponding exponential fit from 1 s onward.
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