Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:2506.00177 · Physical Review A

Creation of a degenerate Bose-Bose mixture of erbium and lithium atoms

Jasmine Kalia, Jared Rivera, Rubaiya R. Emran, William J. Solorio Hernandez, Kiryang Kwon, Richard J. Fletcher

Published Dec 19, 2025• 3 citations
arXivHTMLPDF

Abstract

We report the realization of a degenerate mixture of $^{166}$Er and $^{7}$Li atoms in their energetically lowest spin states. The two species are sequentially laser-cooled and loaded into an optical dipole trap, then transported to a glass cell and simultaneously evaporated to degeneracy. Er serves as the coolant for Li, and we observe efficient sympathetic cooling facilitated by a large interspecies elastic scattering cross section. Three-body losses are found to be small, making this platform promising for the study of interacting mixtures with large mass imbalance.

DOI
10.1103/jq84-tb52

Related papers

Preparation and manipulation of quantum degenerate erbium-lithium mixtures

Jared Rivera

Ultracold atoms are powerful platforms through which to study many-body physics. In recent years there has been a marked increase in the number and variety of species (lanthanides, transition metals, dipolar molecules, etc.) brought to ultracold temperatures, providing new ingredients from which to build interesting systems. In this thesis I report on the design and construction of an erbium-lithium mixture apparatus with broad applicability for quantum simulation. The combination of large mass imbalance, competition of interaction length scales, and variable quantum statistics points toward this mixture hosting a rich variety of Bose-Bose and Bose-Fermi phases with applications ranging from condensed matter to astrophysics. Leveraging these desirable properties, however, necessitated the development of a new quantum gas platform. The first section of this thesis is dedicated to describing that process in detail. The second section of this thesis describes the development of experimental sequences through which we synthesize quantum gases. In our experiments we successively laser cool each species before combining them in a suite of optical dipole traps for evaporative cooling to degeneracy. I finally present our creation of the first degenerate Bose-Bose mixture of erbium-166 and lithium-7, as well as a measurement of the interspecies s-wave scattering length.

•May 1, 2026•0 citations

A quantum degenerate Bose–Fermi mixture of 41 K and 6 Li

Yu-Ping Wu, Xing-Can Yao, Hao-Ze Chen +4 more

Abstract We report a new apparatus for the study of two-species quantum degenerate mixture of 41 K and 6 Li atoms. We develop and combine several advanced cooling techniques to achieve both a large atom number and high phase space density of the two-species atom clouds. Furthermore, we build a high efficiency two-species magnetic transport system to transfer atom clouds from the 3D magneto-optical-trap chamber to a full glass science chamber of an extreme high vacuum environment and good optical access. We perform a forced radio-frequency evaporative cooling for 41 K atoms while the 6 Li atoms are sympathetically cooled in an optically plugged magnetic trap. Finally, we achieve the simultaneous quantum degeneracy for the 41 K and 6 Li atoms. The Bose–Einstein condensate of 41 K has 1.4 × 10 5 atoms with a condensate fraction of about 62%, while the degenerate Fermi gas of 6 Li has a total atom number of 5.4 × 10 5 at 0.25 Fermi temperature.

arXiv:1702.08630•Journal of Physics B Atomic Molecular and Optical Physics•Mar 9, 2017•19 citations

Quantum Degenerate Mixtures of Alkali and Alkaline-Earth-Like Atoms

Hideaki Hara, Yosuke Takasu, Yoshifumi Yamaoka +2 more

We realize simultaneous quantum degeneracy in mixtures consisting of the alkali and alkaline-earth-like atoms Li and Yb. This is accomplished within an optical trap by sympathetic cooling of the fermionic isotope $^{6}\mathrm{Li}$ with evaporatively cooled bosonic $^{174}\mathrm{Yb}$ and, separately, fermionic $^{173}\mathrm{Yb}$. Using cross-thermalization studies, we also measure the elastic $s$-wave scattering lengths of both Li-Yb combinations, $|{a}_{^{6}\mathrm{Li}\ensuremath{-}^{174}\mathrm{Yb}}|=1.0\ifmmode\pm\else\textpm\fi{}0.2\text{ }\text{ }\mathrm{nm}$ and $|{a}_{^{6}\mathrm{Li}\ensuremath{-}^{173}\mathrm{Yb}}|=0.9\ifmmode\pm\else\textpm\fi{}0.2\text{ }\text{ }\mathrm{nm}$. The equality of these lengths is found to be consistent with mass-scaling analysis. The quantum degenerate mixtures of Li and Yb, as realized here, can be the basis for creation of ultracold molecules with electron spin degrees of freedom, studies of novel Efimov trimers, and impurity probes of superfluid systems.

arXiv:1104.4430•Physical Review Letters•May 19, 2011•158 citations

Dual-species Bose-Einstein condensates of $^{7}$Li and $^{133}$Cs

Y.-D. Chen, W. -X. Li, Y.-T. Sun +3 more

We report the creation of dual-species Bose-Einstein condensates (BECs) of $^{7}$Li and $^{133}$Cs. These BECs are formed in a bichromatic optical dipole trap created with 1550-nm and 780-nm laser beams. During the production process, an external magnetic field of 886~G is applied to adjust the scattering lengths to $a_{\rm{Cs}} = 123a_0$, $a_{\rm{Li}} = 484a_0$, and $a_{\rm{LiCs}} = 248a_0$. These scattering lengths allow for efficient evaporation and sympathetic cooling. The dual-species BECs are typically produced with $1.5\times 10^4$ Cs atoms and $6.0\times 10^3$ Li atoms. This quantum degenerate mixture of Li and Cs provides an ideal platform for exploring phenomena such as polarons and Efimov trimers, as well as for creating ground-state LiCs molecules.

arXiv:2306.02698•Jun 5, 2023•0 citations

Quantum degenerate mixture of ytterbium and lithium atoms

Anders H. Hansen, Alexander Y. Khramov, William H. Dowd +3 more

We have produced a quantum degenerate mixture of fermionic alkali-metal ${}^{6}$Li and bosonic spin-singlet ${}^{174}$Yb gases. This was achieved using sympathetic cooling of lithium atoms by evaporatively cooled ytterbium atoms in a far-off-resonant optical dipole trap. We observe the coexistence of Bose-condensed ($T/{T}_{\mathrm{c}}\ensuremath{\simeq}0.8$) ${}^{174}$Yb with $2.3\ifmmode\times\else\texttimes\fi{}{10}^{4}$ atoms and Fermi degenerate ($T/{T}_{\mathrm{F}}\ensuremath{\simeq}0.3$) ${}^{6}$Li with $1.2\ifmmode\times\else\texttimes\fi{}{10}^{4}$ atoms. Quasipure Bose-Einstein condensates of up to $3\ifmmode\times\else\texttimes\fi{}{10}^{4}$ ${}^{174}$Yb atoms can be produced in single-species experiments. Our results mark a significant step toward studies of few- and many-body physics with mixtures of alkali-metal and alkaline-earth-metal-like atoms, and for the production of paramagnetic polar molecules in the quantum regime. Our methods also establish a convenient scheme for producing quantum degenerate ytterbium atoms in a 1064 nm optical dipole trap.

arXiv:1105.5751•Physical Review A•Jul 22, 2011•83 citations

All-Optical Production of Quantum Degeneracy and Molecular Bose-Einstein Condensation of 6 Li

Shu-Jin Deng, Peng-Peng Diao, Qian-Li Yu +1 more

We achieve a highly degenerate and strongly interacting Fermi gas in a mixture of the two lowest hyperfine states of 6 Li by direct evaporative cooling in a high power crossed optical dipole trap. The trap is loaded from a large atom number magneto-optical trap realized by a laser system of 2.5-W intracavity-frequency-doubled light output at 671 nm. With this system, we also demonstrate the production of a molecular Bose-Einstein condensate (mBEC) of 6 Li 2 , and observe the anisotropic expansion of Fermi gases in the so-called BEC-Bardeen-Cooper-Schrieffer crossover regime.

arXiv:1502.00280•Chinese Physics Letters•May 1, 2015•13 citations
We report the realization of a degenerate mixture of 166^{166}166Er and 7^{7}7Li atoms in their energetically lowest spin states. The two species are sequentially laser-cooled and loaded into an optical dipole trap, then transported to a glass cell and simultaneously evaporated to degeneracy. Er serves as the coolant for Li, and we observe efficient sympathetic cooling facilitated by a large interspecies elastic scattering cross section. Three-body losses are found to be small, making this platform promising for the study of interacting mixtures with large mass imbalance.
Ultracold atoms are powerful platforms through which to study many-body physics. In recent years there has been a marked increase in the number and variety of species (lanthanides, transition metals, dipolar molecules, etc.) brought to ultracold temperatures, providing new ingredients from which to build interesting systems. In this thesis I report on the design and construction of an erbium-lithium mixture apparatus with broad applicability for quantum simulation. The combination of large mass imbalance, competition of interaction length scales, and variable quantum statistics points toward this mixture hosting a rich variety of Bose-Bose and Bose-Fermi phases with applications ranging from condensed matter to astrophysics. Leveraging these desirable properties, however, necessitated the development of a new quantum gas platform. The first section of this thesis is dedicated to describing that process in detail. The second section of this thesis describes the development of experimental sequences through which we synthesize quantum gases. In our experiments we successively laser cool each species before combining them in a suite of optical dipole traps for evaporative cooling to degeneracy. I finally present our creation of the first degenerate Bose-Bose mixture of erbium-166 and lithium-7, as well as a measurement of the interspecies s-wave scattering length.
Abstract We report a new apparatus for the study of two-species quantum degenerate mixture of 41 K and 6 Li atoms. We develop and combine several advanced cooling techniques to achieve both a large atom number and high phase space density of the two-species atom clouds. Furthermore, we build a high efficiency two-species magnetic transport system to transfer atom clouds from the 3D magneto-optical-trap chamber to a full glass science chamber of an extreme high vacuum environment and good optical access. We perform a forced radio-frequency evaporative cooling for 41 K atoms while the 6 Li atoms are sympathetically cooled in an optically plugged magnetic trap. Finally, we achieve the simultaneous quantum degeneracy for the 41 K and 6 Li atoms. The Bose–Einstein condensate of 41 K has 1.4 × 10 5 atoms with a condensate fraction of about 62%, while the degenerate Fermi gas of 6 Li has a total atom number of 5.4 × 10 5 at 0.25 Fermi temperature.
We realize simultaneous quantum degeneracy in mixtures consisting of the alkali and alkaline-earth-like atoms Li and Yb. This is accomplished within an optical trap by sympathetic cooling of the fermionic isotope 6Li^{6}\mathrm{Li}6Li with evaporatively cooled bosonic 174Yb^{174}\mathrm{Yb}174Yb and, separately, fermionic 173Yb^{173}\mathrm{Yb}173Yb. Using cross-thermalization studies, we also measure the elastic sss-wave scattering lengths of both Li-Yb combinations, $|{a}_{^{6}\mathrm{Li}\ensuremath{-}^{174}\mathrm{Yb}}|=1.0\ifmmode\pm\else\textpm\fi{}0.2\text{ }\text{ }\mathrm{nm}$ and $|{a}_{^{6}\mathrm{Li}\ensuremath{-}^{173}\mathrm{Yb}}|=0.9\ifmmode\pm\else\textpm\fi{}0.2\text{ }\text{ }\mathrm{nm}$. The equality of these lengths is found to be consistent with mass-scaling analysis. The quantum degenerate mixtures of Li and Yb, as realized here, can be the basis for creation of ultracold molecules with electron spin degrees of freedom, studies of novel Efimov trimers, and impurity probes of superfluid systems.
Dual-species Bose-Einstein condensates of 7^{7}7Li and 133^{133}133Cs
We report the creation of dual-species Bose-Einstein condensates (BECs) of 7^{7}7Li and 133^{133}133Cs. These BECs are formed in a bichromatic optical dipole trap created with 1550-nm and 780-nm laser beams. During the production process, an external magnetic field of 886~G is applied to adjust the scattering lengths to aCs=123a0a_{\rm{Cs}} = 123a_0aCs​=123a0​, aLi=484a0a_{\rm{Li}} = 484a_0aLi​=484a0​, and aLiCs=248a0a_{\rm{LiCs}} = 248a_0aLiCs​=248a0​. These scattering lengths allow for efficient evaporation and sympathetic cooling. The dual-species BECs are typically produced with 1.5×1041.5\times 10^41.5×104 Cs atoms and 6.0×1036.0\times 10^36.0×103 Li atoms. This quantum degenerate mixture of Li and Cs provides an ideal platform for exploring phenomena such as polarons and Efimov trimers, as well as for creating ground-state LiCs molecules.
We have produced a quantum degenerate mixture of fermionic alkali-metal 6{}^{6}6Li and bosonic spin-singlet 174{}^{174}174Yb gases. This was achieved using sympathetic cooling of lithium atoms by evaporatively cooled ytterbium atoms in a far-off-resonant optical dipole trap. We observe the coexistence of Bose-condensed ($T/{T}_{\mathrm{c}}\ensuremath{\simeq}0.8$) 174{}^{174}174Yb with $2.3\ifmmode\times\else\texttimes\fi{}{10}^{4}$ atoms and Fermi degenerate ($T/{T}_{\mathrm{F}}\ensuremath{\simeq}0.3$) 6{}^{6}6Li with $1.2\ifmmode\times\else\texttimes\fi{}{10}^{4}$ atoms. Quasipure Bose-Einstein condensates of up to $3\ifmmode\times\else\texttimes\fi{}{10}^{4}$ 174{}^{174}174Yb atoms can be produced in single-species experiments. Our results mark a significant step toward studies of few- and many-body physics with mixtures of alkali-metal and alkaline-earth-metal-like atoms, and for the production of paramagnetic polar molecules in the quantum regime. Our methods also establish a convenient scheme for producing quantum degenerate ytterbium atoms in a 1064 nm optical dipole trap.
We achieve a highly degenerate and strongly interacting Fermi gas in a mixture of the two lowest hyperfine states of 6 Li by direct evaporative cooling in a high power crossed optical dipole trap. The trap is loaded from a large atom number magneto-optical trap realized by a laser system of 2.5-W intracavity-frequency-doubled light output at 671 nm. With this system, we also demonstrate the production of a molecular Bose-Einstein condensate (mBEC) of 6 Li 2 , and observe the anisotropic expansion of Fermi gases in the so-called BEC-Bardeen-Cooper-Schrieffer crossover regime.