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arXiv:2105.01438 · Physical Review Research

Observation of a narrow inner-shell orbital transition in atomic erbium at 1299 nm

A. Patscheider, B. Yang, G. Natale, Daniel Petter, Lauriane Chomaz, M. J. Mark, G. Hovhannesyan, Maxence Lepers, F. Ferlaino

Published Sep 17, 2021• 21 citations
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Abstract

We report on the observation and coherent excitation of atoms on the narrow inner-shell orbital transition, connecting the erbium ground state $[\mathrm{Xe}]4{f}^{12}{(}^{3}{\text{H}}_{6})6{s}^{2}$ to the excited state $[\mathrm{Xe}]4{f}^{11}({{(}^{4}{\text{I}}_{15/2})}^{0})5d{(}^{5}{\text{D}}_{3/2})6{s}^{2}{(15/2,3/2)}_{7}^{0}$. This transition corresponds to a wavelength of 1299 nm and is optically closed. We perform high-resolution spectroscopy to extract the ${g}_{J}$ factor of the 1299-nm state and to determine the frequency shift for four bosonic isotopes. We further demonstrate coherent control of the atomic state and extract a lifetime of 178(19) ms, which corresponds to a linewidth of 0.9(1) Hz. The experimental findings are in good agreement with our semi-empirical model. In addition, we present theoretical calculations of the atomic polarizability, revealing several different magic-wavelength conditions. Finally, we make use of the vectorial polarizability and confirm a possible magic wavelength at 532 nm.

DOI
10.1103/physrevresearch.3.033256

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Observation of a narrow inner-shell orbital transition in atomic erbium at 1299 nm

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We report on the observation and coherent excitation of atoms on the narrow inner-shell orbital transition, connecting the erbium ground state [Xe]4f12(3H6)6s2 to the excited state [Xe]4f11((4I15/2)0)5d(5D3/2)6s2(15/2,3/2)70. This transition corresponds to a wavelength of 1299 nm and is optically closed. We perform high-resolution spectroscopy to extract the gJ factor of the 1299-nm state and to determine the frequency shift for four bosonic isotopes. We further demonstrate coherent control of the atomic state and extract a lifetime of 178(19) ms, which corresponds to a linewidth of 0.9(1) Hz. The experimental findings are in good agreement with our semi-empirical model. In addition, we present theoretical calculations of the atomic polarizability, revealing several different magic-wavelength conditions. Finally, we make use of the vectorial polarizability and confirm a possible magic wavelength at 532 nm.

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We report on the observation and coherent excitation of atoms on the narrow inner-shell orbital transition, connecting the erbium ground state [Xe]4f12(3H6)6s2[\mathrm{Xe}]4{f}^{12}{(}^{3}{\text{H}}_{6})6{s}^{2}[Xe]4f12(3H6​)6s2 to the excited state [Xe]4f11((4I15/2)0)5d(5D3/2)6s2(15/2,3/2)70[\mathrm{Xe}]4{f}^{11}({{(}^{4}{\text{I}}_{15/2})}^{0})5d{(}^{5}{\text{D}}_{3/2})6{s}^{2}{(15/2,3/2)}_{7}^{0}[Xe]4f11((4I15/2​)0)5d(5D3/2​)6s2(15/2,3/2)70​. This transition corresponds to a wavelength of 1299 nm and is optically closed. We perform high-resolution spectroscopy to extract the gJ{g}_{J}gJ​ factor of the 1299-nm state and to determine the frequency shift for four bosonic isotopes. We further demonstrate coherent control of the atomic state and extract a lifetime of 178(19) ms, which corresponds to a linewidth of 0.9(1) Hz. The experimental findings are in good agreement with our semi-empirical model. In addition, we present theoretical calculations of the atomic polarizability, revealing several different magic-wavelength conditions. Finally, we make use of the vectorial polarizability and confirm a possible magic wavelength at 532 nm.
We report on the observation and coherent excitation of atoms on the narrow inner-shell orbital transition, connecting the erbium ground state [Xe]4f12(3H6)6s2 to the excited state [Xe]4f11((4I15/2)0)5d(5D3/2)6s2(15/2,3/2)70. This transition corresponds to a wavelength of 1299 nm and is optically closed. We perform high-resolution spectroscopy to extract the gJ factor of the 1299-nm state and to determine the frequency shift for four bosonic isotopes. We further demonstrate coherent control of the atomic state and extract a lifetime of 178(19) ms, which corresponds to a linewidth of 0.9(1) Hz. The experimental findings are in good agreement with our semi-empirical model. In addition, we present theoretical calculations of the atomic polarizability, revealing several different magic-wavelength conditions. Finally, we make use of the vectorial polarizability and confirm a possible magic wavelength at 532 nm.
We observe a weakly allowed optical transition of atomic ytterbium from the ground state to the metastable state 4f^{13}5d6s^{2} (J=2) for all five bosonic and two fermionic isotopes with resolved Zeeman and hyperfine structures. This inner-shell orbital transition has been proposed as a new frequency standard as well as a quantum sensor for new physics. We find magic wavelengths through the measurement of the scalar and tensor polarizabilities and reveal that the measured trap lifetime in a three-dimensional optical lattice is 1.9(1) s, which is crucial for precision measurements. We also determine the g factor by an interleaved measurement, consistent with our relativistic atomic calculation. This work opens the possibility of an optical lattice clock with improved stability and accuracy as well as novel approaches for physics beyond the standard model.
Rare-earth (RE) atoms, such as erbium (Er), have inner-shell optical transitions in the near-infrared, some of which are in the telecom bands. These transitions are largely insensitive to the host environment due to effective shielding by the filled outer shells. Cryogenic rare-gas (RG) solids, such as solid neon (Ne) and argon (Ar), combine high chemical purity with a nearly nuclear-spin-free environment, making them attractive solid hosts for preserving optical and spin coherence. In this work, we isolate neutral Er atoms in solid Ne and Ar at 6 K and characterize their emission by steady-state and time-resolved photoluminescence (PL) spectroscopy. In both hosts, we observe several near-infrared transitions between 1000--1500 nm, including inner-shell emission in the telecom O and E bands. The 4f→5d4f \rightarrow 5d4f→5d transition near 1299 nm forms a multiplet of narrow components, consistent with crystal-field splitting, and decays on a microsecond timescale. The 4f→4f4f \rightarrow 4f4f→4f transition near 1437 nm shows a matrix shift below 1 cm−1^{-1}−1 in both hosts. In solid Ne, its inhomogeneous linewidth is bounded by the spectrometer resolution to < 22 GHz, and its PL lifetime reaches up to 78.9 ms, close to the estimated radiative limit. Thermal annealing extends the 1437 nm lifetime in Ne and suppresses the phonon sidebands relative to the zero-phonon lines in Ar. These results identify RG solids as promising hosts for long-lived telecom-band Er emission and provide a foundation for future spin-photon interfaces and hybrid quantum architectures.
We have measured and analyzed the hyperfine structure of two lines, one at 583 nm and one at 401 nm, of the only stable fermionic isotope of atomic erbium as well as determined its isotope shift relative to the four most-abundant bosonic isotopes. Our work focuses on the $J\ensuremath{\rightarrow}J+1$ laser cooling transitions from the [Xe]4f126s2(3H6)[\text{Xe}]4{f}^{12}6{s}^{2}{(}^{3}{H}_{6})[Xe]4f126s2(3H6​) ground state to two levels of the excited [Xe]4f126s6p[\text{Xe}]4{f}^{12}6s6p[Xe]4f126s6p configuration, which are of major interest for experiments on quantum degenerate dipolar Fermi gases. From a fit to the observed spectra of the strong optical transition at 401 nm we find that the magnetic dipole and electric quadrupole hyperfine constants for the excited state are ${A}_{e}/h=\ensuremath{-}100.1(3)\phantom{\rule{0.28em}{0ex}}\mathrm{MHz}$ and ${B}_{e}/h=\ensuremath{-}3079(30)\phantom{\rule{0.28em}{0ex}}\mathrm{MHz}$, respectively. The hyperfine spectrum of the narrow transition at 583 nm, was previously observed and accurate Ae{A}_{e}Ae​ and Be{B}_{e}Be​ coefficients are available. A simulated spectrum based on these coefficients agrees well with our measurements. We have also determined the hyperfine constants using relativistic configuration-interaction ab initio calculations. The agreement between the ab initio and fitted data for the ground state is better than 0.1%, while for the two excited states the agreement is 1% and 11% for the Ae{A}_{e}Ae​ and Be{B}_{e}Be​ constants, respectively.
Optical lattice clocks of fermionic strontium offer a versatile platform for probing fundamental physics and developing quantum technologies. The bivalent electronic structure of strontium gives rise to a doubly forbidden atomic transition that is accessible due to hyperfine mixing in fermionic strontium-87, thus resulting in a submillihertz natural linewidth. Currently, the most accurate optical lattice clocks operate on this narrow transition by tightly trapping strontium-87 atoms in a optical lattice at 813 nm. Magic wavelengths occur where the Stark shifts of both the ground and excited states are equal, thus eliminating any position- and intensity-dependent broadening of the corresponding transition. Theoretical calculations of the electronic structure of strontium-87 have also predicted another magic wavelength of the clock transition at 497.01(57) nm. In this work, we experimentally measure the magic wavelength to be 497.4364(4) nm. Compared to the 813-nm magic wavelength, 497 nm is closer to the strong 461-nm dipolar transition of strontium, resulting in an order-of-magnitude increase in atomic polarizability and deeper traps with less optical power. The proximity to the 461-nm transition also leads to an enhanced sensitivity of 334(10) Hz/(nm E R ) at the magic wavelength.
We report on spectroscopy of cold dysprosium atoms on the $1001\text{\ensuremath{-}}\mathrm{nm}$ transition and present measurements of the excited-state lifetime which is at least 87(7)ms87(7)\phantom{\rule{4pt}{0ex}}\mathrm{ms}87(7)ms long. Due to the long excited-state lifetime we are able to measure the ratio of the excited-state polarizability to the ground-state polarizability at 1064nm1064\phantom{\rule{4pt}{0ex}}\mathrm{nm}1064nm to be 0.83(0.13) by parametric heating in an optical dipole trap. In addition we measure the isotope shifts of the three most abundant bosonic isotopes of dysprosium on the $1001\text{\ensuremath{-}}\mathrm{nm}$ transition with an accuracy better than 30kHz30\phantom{\rule{4pt}{0ex}}\mathrm{kHz}30kHz.