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:1310.4014 · Europhysics Letters (EPL)

Gray-molasses cooling of 39 K to a high phase-space density

Guillaume Salomon, Lauriane Fouché, Pengjun Wang, Alain Aspect, Philippe Bouyer, Thomas Bourdel

Published Dec 1, 2013• 112 citations
arXivHTMLPDF

Abstract

We present new techniques in cooling 39 K atoms using laser light close to the D1 transition.First, a new compressed-MOT configuration is taking advantage of gray-molasses-type cooling induced by blue-detuned D1 light.It yields an optimized density of atoms.Then, we use pure D1 gray molasses to further cool the atoms to an ultra-low temperature of 6 μK.The resulting phase-space density is 2 × 10 -4 and will ease future experiments with ultracold potassium.As an example, we use it to directly load up to 3 × 10 7 atoms in a far detuned optical trap, a result that opens the way to the all-optical production of potassium degenerate gases.

DOI
10.1209/0295-5075/104/63002

Related papers

Técnica de resfriamento molasses cinza para a otimização de temperatura do 39K

Edward Gutenberg Iraita Salcedo

Alkali-metal atoms are the foremost candidates for studies of degenerate quantum gases employing sub-Doppler cooling techniques operating either on the D1 or D2 transition. However, the case of 39K atoms has a narrow excited-state structure of the D2 transition compromising difficulty to achieve below the Doppler limit temperature (TD = hΓ/2kB = 140μK) by employing conventional cooling techniques such as optical molasses or polarization gradient cooling on this transition. In this work, a sub-Doppler cooling known as Gray molasses operating on the ¦42S½} → ¦42P½} 770nm transition D1 is applied to cool a cloud of 39K atoms to sub-Doppler temperatures, which is an important step to reach the quantum degeneracy of the quantum gases. With this approach we reach temperatures below the Doppler limit around 14.3μK by the formation of dark states using the cooling and repumping lasers detuned to the blue side at the Raman resonance (two-photon) in Λ configuration. Then, we ramp down the intensities of each laser beam, in order to cool the atoms to an ultra-low temperature of 8.62μK, getting closer to the photon recoil limit of (Tr = h2k2L/2mkB = 0.4μK). In our results, we present a study of the behaviour of the temperature and the number of atoms by the influence of the relative detuning, and also a particular analysis of the temperature by the influence of the global detuning. In the following, we present the lowest temperature as a function of the final intensities D1 molasses. Finally, we compare the performance of our Gray molasses cloud with other works by using a phase space density analysis.

•Aug 5, 2021•0 citations

Comparison of an efficient implementation of gray molasses to narrow-line cooling for the all-optical production of a lithium quantum gas

Christine Satter, Shina Tan, Kai Dieckmann

We present an efficient scheme to implement a gray optical molasses for sub-Doppler cooling of $^{6}\mathrm{Li}$ atoms with minimum experimental overhead. To integrate the ${D}_{1}$ light for the gray molasses cooling into the same optical setup that is used for the ${D}_{2}$ light for a standard magneto-optical trap (MOT), we rapidly switch the injection seeding of a slave laser between the ${D}_{2}$ and the ${D}_{1}$ light sources. Switching times as short as 30 $\ensuremath{\mu}\mathrm{s}$ can be achieved, inferred from monitor optical beat signals. The resulting low-intensity molasses cools a sample of $N=9\ifmmode\times\else\texttimes\fi{}{10}^{8}$ atoms to about 60 $\ensuremath{\mu}\mathrm{K}$. A maximum phase-space density of $\ensuremath{\rho}=1.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ is observed. On the same setup, the performance of the GM is compared to that of narrow-line cooling in an ultraviolet (UV) MOT, following the procedure in Sebastian et al. [J. Sebastian, Ch. Gross, K. Li, H. C. J. Gan, W. Li, and K. Dieckmann, Phys. Rev. A 90, 033417 (2014)]. Further, we compare the production of a degenerate Fermi gas using both methods. Loading an optical dipole trap from the gray molasses yields a quantum degenerate sample with $3.3\ifmmode\times\else\texttimes\fi{}{10}^{5}$ atoms, while loading from the denser UV MOT yields $2.4\ifmmode\times\else\texttimes\fi{}{10}^{6}$ atoms. Where the highest atom numbers are not a priority this implementation of the gray molasses technique yields sufficiently large samples for a comparatively low technical effort.

arXiv:1808.06836•Physical Review A•Aug 24, 2018•10 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

Sub-Doppler laser cooling of40K with Raman gray molasses on the ${D}_{2}$ line

G D Bruce, E Haller, Bruno Peaudecerf +6 more

Gray molasses is a powerful tool for sub-Doppler laser cooling of atoms to low temperatures. For alkaline atoms, this technique is commonly implemented with cooling lasers which are blue-detuned from either the D 1 or D 2 line. Here we show that efficient gray molasses can be implemented on the D 2 line of 40 K with red -detuned lasers. We obtained temperatures of , which enables direct loading of atoms from a magneto-optical trap into an optical dipole trap. We support our findings by a one-dimensional model and three-dimensional numerical simulations of the optical Bloch equations which qualitatively reproduce the experimentally observed cooling effects.

arXiv:1612.04583•Journal of Physics B Atomic Molecular and Optical Physics•Apr 12, 2017•24 citations

A Laser System for Gray-Molasses Cooling on the D1 Transition of an Atomic Gas of 39K

Baraa Shammout

In this work we present the design and the construction of a laser system for cooling an atomic gas of potassium 39K on the D1-Line by gray molasses technique. The seed laser is an Interference-filter-stabilized external-cavity diode laser (ECDL). The laser frequency is stabilized to one of the atomic features of 39K D1-transition thanks to frequency modulation (FM) spectroscopy. The low seed power is then amplified by means of tapered amplifier (TA). Finally, the cooling and repumping beams are generated and blue-detuned from the atomic transitions |F = 2> → |F'= 2> and |F = 1> → |F'= 2> using two acousto-optic modulators (AOMs).

•Jan 1, 2020•2 citations

Laser cooling of cesium atoms in gray optical molasses down to 1.1 μK

Denis Boiron, A. Michaud, P. Lemonde +6 more

We have studied the behavior of cesium atoms cooled in six-beam "gray" optical molasses. Cooling occurs for a laser detuned to the blue side of the $6{S}_{\frac{1}{2}}$, $F=3\ensuremath{\rightarrow}6{P}_{\frac{3}{2}}$, ${F}^{\ensuremath{'}}=2$ transition, and a Sisyphus-type effect accumulates the atoms in states not coupled to the light. We measure a minimum temperature of 1.1\ifmmode\pm\else\textpm\fi{}0.1 \ensuremath{\mu}K at low atomic density. The typical cooling time is on the order of 1 ms. A linear dependence of the temperature versus atomic density is found with a slope of \ensuremath{\sim}0.6 \ensuremath{\mu}K/(${10}^{10}$ atoms/${\mathrm{cm}}^{3}$).

Physical Review A•Jun 1, 1996•91 citations
We present new techniques in cooling 39 K atoms using laser light close to the D1 transition.First, a new compressed-MOT configuration is taking advantage of gray-molasses-type cooling induced by blue-detuned D1 light.It yields an optimized density of atoms.Then, we use pure D1 gray molasses to further cool the atoms to an ultra-low temperature of 6 μK.The resulting phase-space density is 2 × 10 -4 and will ease future experiments with ultracold potassium.As an example, we use it to directly load up to 3 × 10 7 atoms in a far detuned optical trap, a result that opens the way to the all-optical production of potassium degenerate gases.
Alkali-metal atoms are the foremost candidates for studies of degenerate quantum gases employing sub-Doppler cooling techniques operating either on the D1 or D2 transition. However, the case of 39K atoms has a narrow excited-state structure of the D2 transition compromising difficulty to achieve below the Doppler limit temperature (TD = hΓ/2kB = 140μK) by employing conventional cooling techniques such as optical molasses or polarization gradient cooling on this transition. In this work, a sub-Doppler cooling known as Gray molasses operating on the ¦42S½} → ¦42P½} 770nm transition D1 is applied to cool a cloud of 39K atoms to sub-Doppler temperatures, which is an important step to reach the quantum degeneracy of the quantum gases. With this approach we reach temperatures below the Doppler limit around 14.3μK by the formation of dark states using the cooling and repumping lasers detuned to the blue side at the Raman resonance (two-photon) in Λ configuration. Then, we ramp down the intensities of each laser beam, in order to cool the atoms to an ultra-low temperature of 8.62μK, getting closer to the photon recoil limit of (Tr = h2k2L/2mkB = 0.4μK). In our results, we present a study of the behaviour of the temperature and the number of atoms by the influence of the relative detuning, and also a particular analysis of the temperature by the influence of the global detuning. In the following, we present the lowest temperature as a function of the final intensities D1 molasses. Finally, we compare the performance of our Gray molasses cloud with other works by using a phase space density analysis.
We present an efficient scheme to implement a gray optical molasses for sub-Doppler cooling of 6Li^{6}\mathrm{Li}6Li atoms with minimum experimental overhead. To integrate the D1{D}_{1}D1​ light for the gray molasses cooling into the same optical setup that is used for the D2{D}_{2}D2​ light for a standard magneto-optical trap (MOT), we rapidly switch the injection seeding of a slave laser between the D2{D}_{2}D2​ and the D1{D}_{1}D1​ light sources. Switching times as short as 30 $\ensuremath{\mu}\mathrm{s}$ can be achieved, inferred from monitor optical beat signals. The resulting low-intensity molasses cools a sample of $N=9\ifmmode\times\else\texttimes\fi{}{10}^{8}$ atoms to about 60 $\ensuremath{\mu}\mathrm{K}$. A maximum phase-space density of $\ensuremath{\rho}=1.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ is observed. On the same setup, the performance of the GM is compared to that of narrow-line cooling in an ultraviolet (UV) MOT, following the procedure in Sebastian et al. [J. Sebastian, Ch. Gross, K. Li, H. C. J. Gan, W. Li, and K. Dieckmann, Phys. Rev. A 90, 033417 (2014)]. Further, we compare the production of a degenerate Fermi gas using both methods. Loading an optical dipole trap from the gray molasses yields a quantum degenerate sample with $3.3\ifmmode\times\else\texttimes\fi{}{10}^{5}$ atoms, while loading from the denser UV MOT yields $2.4\ifmmode\times\else\texttimes\fi{}{10}^{6}$ atoms. Where the highest atom numbers are not a priority this implementation of the gray molasses technique yields sufficiently large samples for a comparatively low technical effort.
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 ${10}^{11}\phantom{\rule{0.28em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$.
Sub-Doppler laser cooling of40K with Raman gray molasses on the D2{D}_{2}D2​ line
Gray molasses is a powerful tool for sub-Doppler laser cooling of atoms to low temperatures. For alkaline atoms, this technique is commonly implemented with cooling lasers which are blue-detuned from either the D 1 or D 2 line. Here we show that efficient gray molasses can be implemented on the D 2 line of 40 K with red -detuned lasers. We obtained temperatures of , which enables direct loading of atoms from a magneto-optical trap into an optical dipole trap. We support our findings by a one-dimensional model and three-dimensional numerical simulations of the optical Bloch equations which qualitatively reproduce the experimentally observed cooling effects.
In this work we present the design and the construction of a laser system for cooling an atomic gas of potassium 39K on the D1-Line by gray molasses technique. The seed laser is an Interference-filter-stabilized external-cavity diode laser (ECDL). The laser frequency is stabilized to one of the atomic features of 39K D1-transition thanks to frequency modulation (FM) spectroscopy. The low seed power is then amplified by means of tapered amplifier (TA). Finally, the cooling and repumping beams are generated and blue-detuned from the atomic transitions |F = 2> → |F'= 2> and |F = 1> → |F'= 2> using two acousto-optic modulators (AOMs).
We have studied the behavior of cesium atoms cooled in six-beam "gray" optical molasses. Cooling occurs for a laser detuned to the blue side of the 6S126{S}_{\frac{1}{2}}6S21​​, $F=3\ensuremath{\rightarrow}6{P}_{\frac{3}{2}}$, ${F}^{\ensuremath{'}}=2$ transition, and a Sisyphus-type effect accumulates the atoms in states not coupled to the light. We measure a minimum temperature of 1.1\ifmmode\pm\else\textpm\fi{}0.1 \ensuremath{\mu}K at low atomic density. The typical cooling time is on the order of 1 ms. A linear dependence of the temperature versus atomic density is found with a slope of \ensuremath{\sim}0.6 \ensuremath{\mu}K/(1010{10}^{10}1010 atoms/cm3{\mathrm{cm}}^{3}cm3).