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

Physical Review A

Simultaneous sub-Doppler laser cooling of Li6 and Li7 isotopes

Gentle Dash, Tim de Jongh, Maxime Dixmerias, Christophe Salomon, Tarik Yefsah

Published Sep 12, 2022• 2 citations
Publisher

Abstract

We report on the simultaneous sub-Doppler laser cooling of $^{6}\mathrm{Li}$ and $^{7}\mathrm{Li}$ isotopes using gray molasses operating on their respective ${D}_{1}$ atomic transitions. For $^{7}\mathrm{Li}$ we show that the sub-Doppler cooling can be achieved with two distinct $\mathrm{\ensuremath{\Lambda}}$-type transitions, where the upper level can be either of the two ${2}^{2}\phantom{\rule{0.16em}{0ex}}{P}_{1/2}$ hyperfine states. We obtain temperatures of $\ensuremath{\sim}85\phantom{\rule{0.16em}{0ex}}\ensuremath{\mu}\mathrm{K}$, with atom numbers of $\ensuremath{\sim}{10}^{8}$, and phase-space densities in the range of ${10}^{\ensuremath{-}6}\ensuremath{-}{10}^{\ensuremath{-}5}$ for both isotopes. These conditions provide a good starting point for loading the mixture into an optical dipole trap and performing evaporative cooling to quantum degeneracy. Our work provides a valuable simplification for the preparation of ultracold $^{6}\mathrm{Li}\ensuremath{-}^{7}\mathrm{Li}$ mixtures, which were proven to be a successful system for the study of impurity physics and Bose-Fermi superfluids.

DOI
10.1103/physreva.106.033105

Related papers

Simultaneous sub-Doppler laser cooling of fermionic Li6 and K40 on the D1 line: Theory and experiment

Franz Sievers, Norman Kretzschmar, Diogo Fernandes +7 more

We report on simultaneous sub-Doppler laser cooling of fermionic $^{6}\mathrm{Li}$ and $^{40}\mathrm{K}$ using the ${D}_{1}$ optical transitions. We compare experimental results to a numerical simulation of the cooling process applying a semiclassical Monte Carlo wave-function method. The simulation takes into account the three-dimensional optical molasses setup and the dipole interaction between atoms and the bichromatic light field driving the ${D}_{1}$ transitions. We discuss the physical mechanisms at play, identify the important role of coherences between the ground-state hyperfine levels, and compare ${D}_{1}$ and ${D}_{2}$ sub-Doppler cooling. In 5 ms, the ${D}_{1}$ molasses phase greatly reduces the temperature for both $^{6}\mathrm{Li}$ and $^{40}\mathrm{K}$ at the same time, with final temperatures of 44 and $11\ensuremath{\mu}\mathrm{K}$, respectively. For both species this leads to a phase-space density close to ${10}^{\ensuremath{-}4}$. These conditions are well suited to direct loading of an optical or magnetic trap for efficient evaporative cooling to quantum degeneracy.

arXiv:1410.8545•Physical Review A•Feb 23, 2015•54 citations

Efficient all-optical production of large Li6 quantum gases using D1 gray-molasses cooling

A. Burchianti, Giacomo Valtolina, Jorge Amin Seman +5 more

We use a gray molasses operating on the ${D}_{1}$ atomic transition to produce degenerate quantum gases of $^{6}\mathrm{Li}$ with a large number of atoms. This sub-Doppler cooling phase allows us to lower the initial temperature of $10{}^{9}$ atoms from 500 to 40 $\ensuremath{\mu}\mathrm{K}$ in 2 ms. We observe that ${D}_{1}$ cooling remains effective into a high-intensity infrared dipole trap where two-state mixtures are evaporated to reach the degenerate regime. We produce molecular Bose-Einstein condensates of up to 5 $\ifmmode\times\else\texttimes\fi{}$ $10{}^{5}$ molecules and weakly interacting degenerate Fermi gases of $7\ifmmode\times\else\texttimes\fi{}{10}^{5}$ atoms at $T/{T}_{F}<0.1$ with a typical experimental duty cycle of 11 s.

arXiv:1406.4788•Physical Review A•Oct 8, 2014•101 citations

Λ -enhanced sub-Doppler cooling of lithium atoms in D 1 gray molasses

Andrew T. Grier, Igor Ferrier-Barbut, Benno S. Rem +4 more

Following the bichromatic sub-Doppler cooling scheme on the ${D}_{1}$ line of ${}^{40}$K recently demonstrated in Fernandes et al. [Europhys. Lett. 100, 63001 (2012)], we introduce a similar technique for ${}^{7}$Li atoms and obtain temperatures of $60\phantom{\rule{0.28em}{0ex}}\ensuremath{\mu}\mathrm{K}$ while capturing all of the $5\ifmmode\times\else\texttimes\fi{}{10}^{8}$ atoms present from the previous stage. We investigate the influence of the detuning between the the two cooling frequencies and observe a threefold decrease of the temperature when the Raman condition is fulfilled. We interpret this effect as arising from extra cooling due to long-lived coherences between hyperfine states. Solving the optical Bloch equations for a simplified $\ensuremath{\Lambda}$-type three-level system we identify the presence of an efficient cooling force near the Raman condition. After transfer into a quadrupole magnetic trap, we measure a phase space density of $\ensuremath{\sim}$${10}^{\ensuremath{-}5}$. This laser cooling offers a promising route for fast evaporation of lithium atoms to quantum degeneracy in optical or magnetic traps.

arXiv:1304.6971•Physical Review A•Jun 12, 2013•132 citations

\Lambda-enhanced Sub-Doppler Cooling of Lithium Atoms in D1 Gray Molasses

Andrew T. Grier, Igor Ferrier-Barbut, Benno S. Rem +4 more

Following the bichromatic sub-Doppler cooling scheme on the D1-line of 40K recently demonstrated in (Fernandes et al. 2012), we introduce a similar technique for 7Li atoms and obtain temperatures of 60 uK while capturing all of the 5x10^8 atoms present from the previous stage. We investigate the influence of the detuning between the the two cooling frequencies and observe a threefold decrease of the temperature when the Raman condition is fulfilled. We interpret this effect as arising from extra cooling due to long-lived coherences between hyperfine states. Solving the optical Bloch equations for a simplified, \Lambda-type three-level system we identify the presence of an efficient cooling force near the Raman condition. After transfer into a quadrupole magnetic trap, we measure a phase space density of ~10^-5. This laser cooling offers a promising route for fast evaporation of lithium atoms to quantum degeneracy in optical or magnetic traps.

•Apr 25, 2013•0 citations

All-optical production of6Li quantum gases

A. Burchianti, Jorge Amin Seman, Giacomo Valtolina +4 more

We report efficient production of quantum gases of 6 Li using a sub-Doppler cooling scheme based on the D 1 transition. After loading in a standard magneto-optical trap, an atomic sample of 10 9 atoms is cooled at a temperature of 40 μ K by a bichromatic D 1 gray-molasses. More than 2 × 10 7 atoms are then transferred into a high-intensity optical dipole trap, where a two-spin state mixture is evaporatively cooled down to quantum degeneracy. We observe that D 1 cooling remains effective in the deep trapping potential, allowing an effective increase of the atomic phase-space density before starting the evaporation. In a total experimental cycle of 11 s, we produce weakly-interacting degenerate Fermi gases of 7 × 10 5 atoms at T/T F < 0.1 and molecular Bose-Einstein condensates of up 5 × 10 5 molecules. We further describe a simple and compact optical system both for high-resolution imaging and for imprinting a thin optical barrier on the atomic cloud; this represents a first step towards the study of quantum tunneling in strongly interacting superfluid Fermi gases.

Journal of Physics Conference Series•Mar 18, 2015•5 citations

Sub-Doppler cooling of sodium atoms in gray molasses

Giacomo Colzi, Gianmaria Durastante, Eleonora Fava +3 more

We report on the realization of sub-Doppler laser cooling of sodium atoms in gray molasses using the ${D}_{1}$ optical transition $(3s\phantom{\rule{0.16em}{0ex}}^{2}S_{1/2}\ensuremath{\rightarrow}3p\phantom{\rule{0.16em}{0ex}}^{2}P_{1/2})$ at 589.8 nm. The technique is applied to samples containing $3\ifmmode\times\else\texttimes\fi{}{10}^{9}$ atoms, previously cooled to $350\phantom{\rule{0.28em}{0ex}}\ensuremath{\mu}\mathrm{K}$ in a magneto-optical trap, and it leads to temperatures as low as $9\phantom{\rule{0.28em}{0ex}}\ensuremath{\mu}\mathrm{K}$ and phase-space densities in the range of ${10}^{\ensuremath{-}4}$. The capture efficiency of the gray molasses is larger than 2/3, and we observe no density-dependent heating for densities up to ${10}^{11}\phantom{\rule{0.28em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$.

arXiv:1512.07053•Physical Review A•Feb 18, 2016•45 citations
We report on the simultaneous sub-Doppler laser cooling of 6Li^{6}\mathrm{Li}6Li and 7Li^{7}\mathrm{Li}7Li isotopes using gray molasses operating on their respective D1{D}_{1}D1​ atomic transitions. For 7Li^{7}\mathrm{Li}7Li we show that the sub-Doppler cooling can be achieved with two distinct \ensuremathΛ\mathrm{\ensuremath{\Lambda}}\ensuremathΛ-type transitions, where the upper level can be either of the two 22P1/2{2}^{2}\phantom{\rule{0.16em}{0ex}}{P}_{1/2}22P1/2​ hyperfine states. We obtain temperatures of \ensuremath∼85\ensuremathμK\ensuremath{\sim}85\phantom{\rule{0.16em}{0ex}}\ensuremath{\mu}\mathrm{K}\ensuremath∼85\ensuremathμK, with atom numbers of \ensuremath∼108\ensuremath{\sim}{10}^{8}\ensuremath∼108, and phase-space densities in the range of 10\ensuremath−6\ensuremath−10\ensuremath−5{10}^{\ensuremath{-}6}\ensuremath{-}{10}^{\ensuremath{-}5}10\ensuremath−6\ensuremath−10\ensuremath−5 for both isotopes. These conditions provide a good starting point for loading the mixture into an optical dipole trap and performing evaporative cooling to quantum degeneracy. Our work provides a valuable simplification for the preparation of ultracold 6Li\ensuremath−7Li^{6}\mathrm{Li}\ensuremath{-}^{7}\mathrm{Li}6Li\ensuremath−7Li mixtures, which were proven to be a successful system for the study of impurity physics and Bose-Fermi superfluids.
We report on simultaneous sub-Doppler laser cooling of fermionic 6Li^{6}\mathrm{Li}6Li and 40K^{40}\mathrm{K}40K using the D1{D}_{1}D1​ optical transitions. We compare experimental results to a numerical simulation of the cooling process applying a semiclassical Monte Carlo wave-function method. The simulation takes into account the three-dimensional optical molasses setup and the dipole interaction between atoms and the bichromatic light field driving the D1{D}_{1}D1​ transitions. We discuss the physical mechanisms at play, identify the important role of coherences between the ground-state hyperfine levels, and compare D1{D}_{1}D1​ and D2{D}_{2}D2​ sub-Doppler cooling. In 5 ms, the D1{D}_{1}D1​ molasses phase greatly reduces the temperature for both 6Li^{6}\mathrm{Li}6Li and 40K^{40}\mathrm{K}40K at the same time, with final temperatures of 44 and $11\ensuremath{\mu}\mathrm{K}$, respectively. For both species this leads to a phase-space density close to ${10}^{\ensuremath{-}4}$. These conditions are well suited to direct loading of an optical or magnetic trap for efficient evaporative cooling to quantum degeneracy.
We use a gray molasses operating on the D1{D}_{1}D1​ atomic transition to produce degenerate quantum gases of 6Li^{6}\mathrm{Li}6Li with a large number of atoms. This sub-Doppler cooling phase allows us to lower the initial temperature of 10910{}^{9}109 atoms from 500 to 40 $\ensuremath{\mu}\mathrm{K}$ in 2 ms. We observe that D1{D}_{1}D1​ cooling remains effective into a high-intensity infrared dipole trap where two-state mixtures are evaporated to reach the degenerate regime. We produce molecular Bose-Einstein condensates of up to 5 $\ifmmode\times\else\texttimes\fi{}$ 10510{}^{5}105 molecules and weakly interacting degenerate Fermi gases of $7\ifmmode\times\else\texttimes\fi{}{10}^{5}$ atoms at T/TF<0.1T/{T}_{F}<0.1T/TF​<0.1 with a typical experimental duty cycle of 11 s.
Following the bichromatic sub-Doppler cooling scheme on the D1{D}_{1}D1​ line of 40{}^{40}40K recently demonstrated in Fernandes et al. [Europhys. Lett. 100, 63001 (2012)], we introduce a similar technique for 7{}^{7}7Li atoms and obtain temperatures of $60\phantom{\rule{0.28em}{0ex}}\ensuremath{\mu}\mathrm{K}$ while capturing all of the $5\ifmmode\times\else\texttimes\fi{}{10}^{8}$ atoms present from the previous stage. We investigate the influence of the detuning between the the two cooling frequencies and observe a threefold decrease of the temperature when the Raman condition is fulfilled. We interpret this effect as arising from extra cooling due to long-lived coherences between hyperfine states. Solving the optical Bloch equations for a simplified $\ensuremath{\Lambda}$-type three-level system we identify the presence of an efficient cooling force near the Raman condition. After transfer into a quadrupole magnetic trap, we measure a phase space density of $\ensuremath{\sim}$${10}^{\ensuremath{-}5}$. This laser cooling offers a promising route for fast evaporation of lithium atoms to quantum degeneracy in optical or magnetic traps.
Following the bichromatic sub-Doppler cooling scheme on the D1-line of 40K recently demonstrated in (Fernandes et al. 2012), we introduce a similar technique for 7Li atoms and obtain temperatures of 60 uK while capturing all of the 5x10^8 atoms present from the previous stage. We investigate the influence of the detuning between the the two cooling frequencies and observe a threefold decrease of the temperature when the Raman condition is fulfilled. We interpret this effect as arising from extra cooling due to long-lived coherences between hyperfine states. Solving the optical Bloch equations for a simplified, \Lambda-type three-level system we identify the presence of an efficient cooling force near the Raman condition. After transfer into a quadrupole magnetic trap, we measure a phase space density of ~10^-5. This laser cooling offers a promising route for fast evaporation of lithium atoms to quantum degeneracy in optical or magnetic traps.
We report efficient production of quantum gases of 6 Li using a sub-Doppler cooling scheme based on the D 1 transition. After loading in a standard magneto-optical trap, an atomic sample of 10 9 atoms is cooled at a temperature of 40 μ K by a bichromatic D 1 gray-molasses. More than 2 × 10 7 atoms are then transferred into a high-intensity optical dipole trap, where a two-spin state mixture is evaporatively cooled down to quantum degeneracy. We observe that D 1 cooling remains effective in the deep trapping potential, allowing an effective increase of the atomic phase-space density before starting the evaporation. In a total experimental cycle of 11 s, we produce weakly-interacting degenerate Fermi gases of 7 × 10 5 atoms at T/T F < 0.1 and molecular Bose-Einstein condensates of up 5 × 10 5 molecules. We further describe a simple and compact optical system both for high-resolution imaging and for imprinting a thin optical barrier on the atomic cloud; this represents a first step towards the study of quantum tunneling in strongly interacting superfluid Fermi gases.
We report on the realization of sub-Doppler laser cooling of sodium atoms in gray molasses using the D1{D}_{1}D1​ optical transition $(3s\phantom{\rule{0.16em}{0ex}}^{2}S_{1/2}\ensuremath{\rightarrow}3p\phantom{\rule{0.16em}{0ex}}^{2}P_{1/2})$ at 589.8 nm. The technique is applied to samples containing $3\ifmmode\times\else\texttimes\fi{}{10}^{9}$ atoms, previously cooled to $350\phantom{\rule{0.28em}{0ex}}\ensuremath{\mu}\mathrm{K}$ in a magneto-optical trap, and it leads to temperatures as low as $9\phantom{\rule{0.28em}{0ex}}\ensuremath{\mu}\mathrm{K}$ and phase-space densities in the range of ${10}^{\ensuremath{-}4}$. The capture efficiency of the gray molasses is larger than 2/3, and we observe no density-dependent heating for densities up to ${10}^{11}\phantom{\rule{0.28em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$.