arXiv:1407.5317 · Physical Review A

All-optical cooling of K39 to Bose-Einstein condensation

Guillaume Salomon, Lauriane Fouché, S. Lepoutre, Alain Aspect, Thomas Bourdel

Published Sep 5, 2014• 40 citations

Abstract

We report the all-optical production of Bose-Einstein condensates (BEC) of $^{39}\mathrm{K}$ atoms. We directly load $3\ifmmode\times\else\texttimes\fi{}{10}^{7}$ atoms in a large volume optical dipole trap from gray molasses on the D1 transition. We then apply a small magnetic quadrupole field to polarize the sample before transferring the atoms in a tightly confining optical trap. Evaporative cooling is finally performed close to a Feshbach resonance to enhance the scattering length. Our setup allows one to cross the BEC threshold with $3\ifmmode\times\else\texttimes\fi{}{10}^{5}$ atoms every 7 s. As an illustration of the interest of the tunability of the interactions we study the expansion of Bose-Einstein condensates in the one-dimensional to three-dimensional crossover.

DOI: 10.1103/physreva.90.033405

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Efficient production of large K39 Bose-Einstein condensates

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Production of dual species Bose–Einstein condensates of 39K and 87Rb*

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Bose-Einstein condensates in a large-volume optical trap

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arXiv:1407.5317 · Physical Review A

All-optical cooling of K39 to Bose-Einstein condensation

Guillaume Salomon, Lauriane Fouché, S. Lepoutre, Alain Aspect, Thomas Bourdel

Published Sep 5, 2014• 40 citations

arXiv HTML PDF

Abstract

We report the all-optical production of Bose-Einstein condensates (BEC) of

^{39}\mathrm{K}

atoms. We directly load

3\ifmmode\times\else\texttimes\fi{}{10}^{7}

atoms in a large volume optical dipole trap from gray molasses on the D1 transition. We then apply a small magnetic quadrupole field to polarize the sample before transferring the atoms in a tightly confining optical trap. Evaporative cooling is finally performed close to a Feshbach resonance to enhance the scattering length. Our setup allows one to cross the BEC threshold with

3\ifmmode\times\else\texttimes\fi{}{10}^{5}

atoms every 7 s. As an illustration of the interest of the tunability of the interactions we study the expansion of Bose-Einstein condensates in the one-dimensional to three-dimensional crossover.

DOI: 10.1103/physreva.90.033405

Related papers

Efficient production of large K39 Bose-Einstein condensates

Robert L. D. Campbell, Robert P. Smith, Naaman Tammuz +3 more

We describe an experimental setup and the cooling procedure for producing $^{39}\mathrm{K}$ Bose-Einstein condensates of over $4\ifmmode\times\else\texttimes\fi{}{10}^{5}$ atoms. Condensation is achieved via a combination of sympathetic cooling with $^{87}\mathrm{Rb}$ in a quadrupole-Ioffe-configuration (QUIC) magnetic trap and direct evaporation in a large-volume crossed optical dipole trap, where we exploit the broad Feshbach resonance at 402 G to tune the $^{39}\mathrm{K}$ interactions from weak and attractive to strong and repulsive. In the same apparatus we create quasipure $^{87}\mathrm{Rb}$ condensates of over $8\ifmmode\times\else\texttimes\fi{}{10}^{5}$ atoms.We describe an experimental setup and the cooling procedure for producing $^{39}\mathrm{K}$ Bose-Einstein condensates of over $4\ifmmode\times\else\texttimes\fi{}{10}^{5}$ atoms. Condensation is achieved via a combination of sympathetic cooling with $^{87}\mathrm{Rb}$ in a quadrupole-Ioffe-configuration (QUIC) magnetic trap and direct evaporation in a large-volume crossed optical dipole trap, where we exploit the broad Feshbach resonance at 402 G to tune the $^{39}\mathrm{K}$ interactions from weak and attractive to strong and repulsive. In the same apparatus we create quasipure $^{87}\mathrm{Rb}$ condensates of over $8\ifmmode\times\else\texttimes\fi{}{10}^{5}$ atoms.

arXiv:1010.3739Physical Review ADec 8, 201045 citations

Production of large K41 Bose-Einstein condensates using D1 gray molasses

Hao-Ze Chen, Xing-Can Yao, Yu-Ping Wu +5 more

We use ${D}_{1}$ gray molasses to achieve Bose-Einstein condensation of a large number of $^{41}\mathrm{K}$ atoms in an optical dipole trap. By combining a specific configuration of a compressed magneto-optical trap with ${D}_{1}$ gray molasses, we obtain a cold sample of $2.4\ifmmode\times\else\texttimes\fi{}{10}^{9}$ atoms with a temperature as low as 42 $\ensuremath{\mu}\mathrm{K}$. After magnetically transferring the atoms into the final glass cell, we perform a two-stage evaporative cooling. A condensate with up to $1.2\ifmmode\times\else\texttimes\fi{}{10}^{6}$ atoms in the lowest Zeeman state $|F=1,{m}_{F}=1\ensuremath{\rangle}$ is achieved in the optical dipole trap. Furthermore, we observe two narrow Feshbach resonances in the lowest hyperfine channel, which are in good agreement with theoretical predictions.We use ${D}_{1}$ gray molasses to achieve Bose-Einstein condensation of a large number of $^{41}\mathrm{K}$ atoms in an optical dipole trap. By combining a specific configuration of a compressed magneto-optical trap with ${D}_{1}$ gray molasses, we obtain a cold sample of $2.4\ifmmode\times\else\texttimes\fi{}{10}^{9}$ atoms with a temperature as low as 42 $\ensuremath{\mu}\mathrm{K}$. After magnetically transferring the atoms into the final glass cell, we perform a two-stage evaporative cooling. A condensate with up to $1.2\ifmmode\times\else\texttimes\fi{}{10}^{6}$ atoms in the lowest Zeeman state $|F=1,{m}_{F}=1\ensuremath{\rangle}$ is achieved in the optical dipole trap. Furthermore, we observe two narrow Feshbach resonances in the lowest hyperfine channel, which are in good agreement with theoretical predictions.

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We report the production of 39K and 87Rb Bose–Einstein condensates (BECs) in the lowest hyperfine states | F = 1,mF = 1 〉 simultaneously. We collect atoms in bright/dark magneto-optical traps (MOTs) of 39K/87Rb to overcome the light-assisted losses of 39K atoms. Gray molasses cooling on the D1 line of the 39K is used to effectively increase the phase density, which improves the loading efficiency of 39K into the quadrupole magnetic trap. Simultaneously, the normal molasses is employed for 87Rb. After the microwave evaporation cooling on 87Rb in the optically plugged magnetic trap, the atoms mixture is transferred to a crossed optical dipole trap, where the collisional properties of the two species in different combinations of the hyperfine states are studied. The dual species BECs of 39K and 87Rb are obtained by further evaporative cooling in an optical dipole trap at a magnetic field of 372.6 G with the background repulsive interspecies scattering length a KRb = 34 a 0 (a 0 is the Bohr radius) and the intraspecies scattering length a K = 20.05a 0.We report the production of 39K and 87Rb Bose–Einstein condensates (BECs) in the lowest hyperfine states | F = 1,mF = 1 〉 simultaneously. We collect atoms in bright/dark magneto-optical traps (MOTs) of 39K/87Rb to overcome the light-assisted losses of 39K atoms. Gray molasses cooling on the D1 line of the 39K is used to effectively increase the phase density, which improves the loading efficiency of 39K into the quadrupole magnetic trap. Simultaneously, the normal molasses is employed for 87Rb. After the microwave evaporation cooling on 87Rb in the optically plugged magnetic trap, the atoms mixture is transferred to a crossed optical dipole trap, where the collisional properties of the two species in different combinations of the hyperfine states are studied. The dual species BECs of 39K and 87Rb are obtained by further evaporative cooling in an optical dipole trap at a magnetic field of 372.6 G with the background repulsive interspecies scattering length a KRb = 34 a 0 (a 0 is the Bohr radius) and the intraspecies scattering length a K = 20.05a 0.

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Bose-Einstein condensates in a large-volume optical trap

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Summary form only given. Bose-Einstein condensates (BEC) are generally produced by evaporative cooling of laser cooled atomic samples in magnetic traps. Though magnetic traps are indispensable for the production of a BEC, they pose restrictions on the possible studies with a BEC. Previous experiments of our group have demonstrated that it is possible to trap a BEC in the circular focus of a far-detuned infrared laser beam. This first realization of an optical dipole trap (ODT) for BEC was used to prepare and investigate spinor condensates of Na atoms in the F=1 hyperfine manifold. However, the initial peak density in this ODT after loading from the magnetic trap reached 10/sup 15/ atoms/cm/sup 3/, leading to rapid losses due to three-body collisions. To realize an ODT capable of storing large condensates for a long time, we have used a laser beam with an elliptical beam profile. The optical trap is loaded by superimposing the light field onto the magnetic trap and then slowly turning off the magnetic fields. The transfer efficiency is close to 100%, and thus more than 10/sup 7/ Bose-condensed atoms can be loaded into the ODT.Summary form only given. Bose-Einstein condensates (BEC) are generally produced by evaporative cooling of laser cooled atomic samples in magnetic traps. Though magnetic traps are indispensable for the production of a BEC, they pose restrictions on the possible studies with a BEC. Previous experiments of our group have demonstrated that it is possible to trap a BEC in the circular focus of a far-detuned infrared laser beam. This first realization of an optical dipole trap (ODT) for BEC was used to prepare and investigate spinor condensates of Na atoms in the F=1 hyperfine manifold. However, the initial peak density in this ODT after loading from the magnetic trap reached 10/sup 15/ atoms/cm/sup 3/, leading to rapid losses due to three-body collisions. To realize an ODT capable of storing large condensates for a long time, we have used a laser beam with an elliptical beam profile. The optical trap is loaded by superimposing the light field onto the magnetic trap and then slowly turning off the magnetic fields. The transfer efficiency is close to 100%, and thus more than 10/sup 7/ Bose-condensed atoms can be loaded into the ODT.

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K39 Bose-Einstein Condensate with Tunable Interactions

G. Roati, Matteo Zaccanti, Chiara D’Errico +5 more

We produce a Bose-Einstein condensate of 39K atoms. Condensation of this species with a naturally small and negative scattering length is achieved by a combination of sympathetic cooling with 87Rb and direct evaporation, exploiting the magnetic tuning of both inter- and intraspecies interactions at Feshbach resonances. We explore the tunability of the self-interactions by studying the expansion and the stability of the condensate. We find that a 39K condensate is interesting for future experiments requiring a weakly-interacting Bose gas.We produce a Bose-Einstein condensate of 39K atoms. Condensation of this species with a naturally small and negative scattering length is achieved by a combination of sympathetic cooling with 87Rb and direct evaporation, exploiting the magnetic tuning of both inter- and intraspecies interactions at Feshbach resonances. We explore the tunability of the self-interactions by studying the expansion and the stability of the condensate. We find that a 39K condensate is interesting for future experiments requiring a weakly-interacting Bose gas.

arXiv:cond-mat/0703714Physical Review LettersJul 6, 2007239 citations

Direct evaporative cooling of 39 K atoms to Bose-Einstein condensation

Manuele Landini, Sanjukta Roy, G. Roati +4 more

We report the realization of a Bose-Einstein condensate of ${}^{39}$ K atoms without the aid of an additional atomic coolant. Our route to Bose-Einstein condensation comprises sub-Doppler laser cooling of large atomic clouds with more than ${10}^{10}$ atoms and evaporative cooling in an optical dipole trap where the collisional cross section can be increased using magnetic Feshbach resonances. Large condensates with almost ${10}^{6}$ atoms can be produced in less than 15 s. Our achievements eliminate the need for sympathetic cooling with Rb atoms, which was the usual route implemented until now due to the unfavorable collisional property of ${}^{39}$ K. Our findings simplify the experimental setup for producing Bose-Einstein condensates of ${}^{39}$ K atoms with tunable interactions, which have a wide variety of promising applications, including atom interferometry to studies on the interplay of disorder and interactions in quantum gases.We report the realization of a Bose-Einstein condensate of ${}^{39}$K atoms without the aid of an additional atomic coolant. Our route to Bose-Einstein condensation comprises sub-Doppler laser cooling of large atomic clouds with more than ${10}^{10}$ atoms and evaporative cooling in an optical dipole trap where the collisional cross section can be increased using magnetic Feshbach resonances. Large condensates with almost ${10}^{6}$ atoms can be produced in less than 15 s. Our achievements eliminate the need for sympathetic cooling with Rb atoms, which was the usual route implemented until now due to the unfavorable collisional property of ${}^{39}$K. Our findings simplify the experimental setup for producing Bose-Einstein condensates of ${}^{39}$K atoms with tunable interactions, which have a wide variety of promising applications, including atom interferometry to studies on the interplay of disorder and interactions in quantum gases.

arXiv:1207.4713Physical Review ASep 20, 201241 citations

We report the all-optical production of Bose-Einstein condensates (BEC) of

^{39}\mathrm{K}

atoms. We directly load

3\ifmmode\times\else\texttimes\fi{}{10}^{7}

3\ifmmode\times\else\texttimes\fi{}{10}^{5}

atoms every 7 s. As an illustration of the interest of the tunability of the interactions we study the expansion of Bose-Einstein condensates in the one-dimensional to three-dimensional crossover.

We describe an experimental setup and the cooling procedure for producing

^{39}\mathrm{K}

Bose-Einstein condensates of over $4\ifmmode\times\else\texttimes\fi{}{10}^{5}$ atoms. Condensation is achieved via a combination of sympathetic cooling with

^{87}\mathrm{Rb}

in a quadrupole-Ioffe-configuration (QUIC) magnetic trap and direct evaporation in a large-volume crossed optical dipole trap, where we exploit the broad Feshbach resonance at 402 G to tune the

^{39}\mathrm{K}

interactions from weak and attractive to strong and repulsive. In the same apparatus we create quasipure

^{87}\mathrm{Rb}

condensates of over $8\ifmmode\times\else\texttimes\fi{}{10}^{5}$ atoms.

We use

{D}_{1}

gray molasses to achieve Bose-Einstein condensation of a large number of

^{41}\mathrm{K}

atoms in an optical dipole trap. By combining a specific configuration of a compressed magneto-optical trap with

{D}_{1}

gray molasses, we obtain a cold sample of $2.4\ifmmode\times\else\texttimes\fi{}{10}^{9}$ atoms with a temperature as low as 42 $\ensuremath{\mu}\mathrm{K}$. After magnetically transferring the atoms into the final glass cell, we perform a two-stage evaporative cooling. A condensate with up to $1.2\ifmmode\times\else\texttimes\fi{}{10}^{6}$ atoms in the lowest Zeeman state $|F=1,{m}_{F}=1\ensuremath{\rangle}$ is achieved in the optical dipole trap. Furthermore, we observe two narrow Feshbach resonances in the lowest hyperfine channel, which are in good agreement with theoretical predictions.

We report the realization of a Bose-Einstein condensate of

{}^{39}

K atoms without the aid of an additional atomic coolant. Our route to Bose-Einstein condensation comprises sub-Doppler laser cooling of large atomic clouds with more than

{10}^{10}

atoms and evaporative cooling in an optical dipole trap where the collisional cross section can be increased using magnetic Feshbach resonances. Large condensates with almost

{10}^{6}

atoms can be produced in less than 15 s. Our achievements eliminate the need for sympathetic cooling with Rb atoms, which was the usual route implemented until now due to the unfavorable collisional property of

{}^{39}

K. Our findings simplify the experimental setup for producing Bose-Einstein condensates of

{}^{39}

K atoms with tunable interactions, which have a wide variety of promising applications, including atom interferometry to studies on the interplay of disorder and interactions in quantum gases.