Measurements of interactions between cold molecules and ultracold atoms can allow for a detailed understanding of fundamental collision processes. These measurements can be done using various experimental geometries, including where both species are in a beam, where one species is trapped, or when both species are trapped. Simultaneous trapping offers significantly longer interaction times and an associated increased sensitivity to rare collision events. However, there are significant practical challenges associated with combining atomic and molecular systems, which often have competing experimental requirements. Here, we describe in detail an experimental system that allows for studies of cold collisions between ultracold atoms and cold molecules in a dual trap, where the atoms and molecules are trapped using static magnetic and electric fields, respectively. As a demonstration of the system's capabilities, we study cold collisions between ammonia ( $^{14}\mathrm{ND}_{3}$ and $^{15}\mathrm{ND}_{3}$ ) molecules and rubidium ( $^{87}\mathrm{Rb}$ and $^{85}\mathrm{Rb}$ ) atoms.Measurements of interactions between cold molecules and ultracold atoms can allow for a detailed understanding of fundamental collision processes. These measurements can be done using various experimental geometries, including where both species are in a beam, where one species is trapped, or when both species are trapped. Simultaneous trapping offers significantly longer interaction times and an associated increased sensitivity to rare collision events. However, there are significant practical challenges associated with combining atomic and molecular systems, which often have competing experimental requirements. Here, we describe in detail an experimental system that allows for studies of cold collisions between ultracold atoms and cold molecules in a dual trap, where the atoms and molecules are trapped using static magnetic and electric fields, respectively. As a demonstration of the system's capabilities, we study cold collisions between ammonia ($^{14}\mathrm{ND}_{3}$ and $^{15}\mathrm{ND}_{3}$) molecules and rubidium ($^{87}\mathrm{Rb}$ and $^{85}\mathrm{Rb}$) atoms.

arXiv:2001.02317Physical Review AMar 16, 20209 citations

Cold N+NH Collisions in a Magnetic Trap

Matthew T. Hummon, Timur V. Tscherbul, Jacek A. Kłos +5 more

We present an experimental and theoretical study of atom-molecule collisions in a mixture of cold, trapped N atoms and NH molecules at a temperature of $\ensuremath{\sim}600\text{ }\text{ }\mathrm{mK}$. We measure a small $\mathrm{N}+\mathrm{NH}$ trap loss rate coefficient of ${k}_{\mathrm{loss}}^{(\mathrm{N}+\mathrm{NH})}=9(5)(3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13}\text{ }\text{ }{\mathrm{cm}}^{3}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$. Accurate quantum scattering calculations based on ab initio interaction potentials are in agreement with experiment and indicate the magnetic dipole interaction to be the dominant loss mechanism. Our theory further indicates the ratio of $\mathrm{N}+\mathrm{NH}$ elastic-to-inelastic collisions remains large ( $>100$ ) into the mK regime.We present an experimental and theoretical study of atom-molecule collisions in a mixture of cold, trapped N atoms and NH molecules at a temperature of $\ensuremath{\sim}600\text{ }\text{ }\mathrm{mK}$. We measure a small $\mathrm{N}+\mathrm{NH}$ trap loss rate coefficient of ${k}_{\mathrm{loss}}^{(\mathrm{N}+\mathrm{NH})}=9(5)(3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13}\text{ }\text{ }{\mathrm{cm}}^{3}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$. Accurate quantum scattering calculations based on ab initio interaction potentials are in agreement with experiment and indicate the magnetic dipole interaction to be the dominant loss mechanism. Our theory further indicates the ratio of $\mathrm{N}+\mathrm{NH}$ elastic-to-inelastic collisions remains large ($>100$) into the mK regime.

arXiv:1009.2513Physical Review LettersFeb 2, 201191 citations

Collisional losses of magnetically trapped cold methyl radicals

Jiahong Hu

Collisions between cold polyatomic molecules and atoms are essential in various processes, including interstellar chemical reactions, quantum tunneling, and precision measurements.The methyl radical was the rst polyatomic radical trapped in a magnetic trap. This was achieved by our group in 2017, where the trapped radicals were trapped at a temperature of approximately 130 mK. The methyl radical has been proposed as a potential candidate for sympathetic cooling, which can achieve temperatures below 1 mK. In order to elucidate the collisional properties of the methyl radical, collisions between magnetically trapped, cold methyl radicals, and room temperature helium and argon atoms were investigated experimentally. This work presents the results of these collisional studies and their comparison with theoretically derived trap loss rates. Quantum diffractive collisions dominate the collisions between room temperature helium atoms and cold methyl radicals in a magnetic trap with a trap depth of about 134 mK. More than 10 % of trap loss is attributed to inelastic collisions, in which the methyl radicals are excited to a rotationally excited state. On the other hand, collisions between cold methyl radicals and room temperature argon at this trap depth is near the border between quantum diffractive collisions and classical collisions.Collisions between cold polyatomic molecules and atoms are essential in various processes, including interstellar chemical reactions, quantum tunneling, and precision measurements.The methyl radical was the rst polyatomic radical trapped in a magnetic trap. This was achieved by our group in 2017, where the trapped radicals were trapped at a temperature of approximately 130 mK. The methyl radical has been proposed as a potential candidate for sympathetic cooling, which can achieve temperatures below 1 mK. In order to elucidate the collisional properties of the methyl radical, collisions between magnetically trapped, cold methyl radicals, and room temperature helium and argon atoms were investigated experimentally. This work presents the results of these collisional studies and their comparison with theoretically derived trap loss rates. Quantum diffractive collisions dominate the collisions between room temperature helium atoms and cold methyl radicals in a magnetic trap with a trap depth of about 134 mK. More than 10 % of trap loss is attributed to inelastic collisions, in which the methyl radicals are excited to a rotationally excited state. On the other hand, collisions between cold methyl radicals and room temperature argon at this trap depth is near the border between quantum diffractive collisions and classical collisions.

Jan 1, 20210 citations

Investigation of cold collisions in a mixtured of trapped atoms

Vanderlei Salvador Bagnato, Gustavo Deczka Telles, Marília Wellichan Mancini +7 more

Jan 1, 20010 citations

^{14}\mathrm{ND}_{3}

and

^{15}\mathrm{ND}_{3}

) molecules and rubidium (

^{87}\mathrm{Rb}

and

^{85}\mathrm{Rb}

) atoms.

\mathrm{N}+\mathrm{NH}

trap loss rate coefficient of ${k}_{\mathrm{loss}}^{(\mathrm{N}+\mathrm{NH})}=9(5)(3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13}\text{ }\text{ }{\mathrm{cm}}^{3}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$. Accurate quantum scattering calculations based on ab initio interaction potentials are in agreement with experiment and indicate the magnetic dipole interaction to be the dominant loss mechanism. Our theory further indicates the ratio of

\mathrm{N}+\mathrm{NH}

elastic-to-inelastic collisions remains large (

>100

) into the mK regime.