In this thesis the dynamics of a trapped ion immersed in \na spatially localized buffer gas is investigated. For a homogeneous buffer gas, the ion’s energy distribution reaches a stable equilibrium only if the mass of the buffer gas atoms is below a critical value. This limitation can be overcome by using multipole traps in combination and/or a spatially confined buffer gas. Using a generalized model \nfor elastic collisions of the ion with the buffer gas atoms, the ion’s energy distribution is numerically determined for arbitrary buffer gas distributions and trap parameters. Three regimes characterized by the respective analytic form of the ion’s equilibrium energy distribution \nare found. One of these is a novel regime at large atom-to-ion mass ratios where the final ion temperature can tuned by adiabatically decreasing the spatial extension of the buffer gas and the effective ion trap depth (forced sympathetic cooling). The second part of the thesis presents a hybrid atom ion trap designed for sympathetic cooling of hydroxide anions. In this hybrid trap the anions are immersed in a cloud of laser cooled rubidium atoms. The translational and rovibrational temperatures of the anions is probed by photodetachment tomography and spectroscopy which shows the first ever indication of sympathetic cooling of anions by laser cooled atoms.In this thesis the dynamics of a trapped ion immersed in \na spatially localized buffer gas is investigated. For a homogeneous buffer gas, the ion’s energy distribution reaches a stable equilibrium only if the mass of the buffer gas atoms is below a critical value. This limitation can be overcome by using multipole traps in combination and/or a spatially confined buffer gas. Using a generalized model \nfor elastic collisions of the ion with the buffer gas atoms, the ion’s energy distribution is numerically determined for arbitrary buffer gas distributions and trap parameters. Three regimes characterized by the respective analytic form of the ion’s equilibrium energy distribution \nare found. One of these is a novel regime at large atom-to-ion mass ratios where the final ion temperature can tuned by adiabatically decreasing the spatial extension of the buffer gas and the effective ion trap depth (forced sympathetic cooling). The second part of the thesis presents a hybrid atom ion trap designed for sympathetic cooling of hydroxide anions. In this hybrid trap the anions are immersed in a cloud of laser cooled rubidium atoms. The translational and rovibrational temperatures of the anions is probed by photodetachment tomography and spectroscopy which shows the first ever indication of sympathetic cooling of anions by laser cooled atoms.

Jan 1, 20160 citations

Efficient Sympathetic Cooling of Trapped Atomic Ions

Grahame Vittorini, Craig Robert Clark, Kenneth R. Brown

Bulletin of the American Physical SocietyJun 16, 20110 citations

Blue-sky bifurcation of ion energies and the limits of neutral-gas sympathetic cooling of trapped ions

Steven J. Schowalter, Alexander J. Dunning, Kuang Chen +3 more

Sympathetic cooling of trapped ions through collisions with neutral buffer gases is critical to a variety of modern scientific fields, including fundamental chemistry, mass spectrometry, nuclear and particle physics, and atomic and molecular physics. Despite its widespread use over four decades, there remain open questions regarding its fundamental limitations. To probe these limits, here we examine the steady-state evolution of up to 10 barium ions immersed in a gas of three-million laser-cooled calcium atoms. We observe and explain the emergence of nonequilibrium behaviour as evidenced by bifurcations in the ion steady-state temperature, parameterized by ion number. We show that this behaviour leads to the limitations in creating and maintaining translationally cold samples of trapped ions using neutral-gas sympathetic cooling. These results may provide a route to studying non-equilibrium thermodynamics at the atomic level.Sympathetic cooling of trapped ions through collisions with neutral buffer gases is critical to a variety of modern scientific fields, including fundamental chemistry, mass spectrometry, nuclear and particle physics, and atomic and molecular physics. Despite its widespread use over four decades, there remain open questions regarding its fundamental limitations. To probe these limits, here we examine the steady-state evolution of up to 10 barium ions immersed in a gas of three-million laser-cooled calcium atoms. We observe and explain the emergence of nonequilibrium behaviour as evidenced by bifurcations in the ion steady-state temperature, parameterized by ion number. We show that this behaviour leads to the limitations in creating and maintaining translationally cold samples of trapped ions using neutral-gas sympathetic cooling. These results may provide a route to studying non-equilibrium thermodynamics at the atomic level.

arXiv:1608.03376Nature CommunicationsAug 11, 201630 citations

Sympathetic cooling of ions in an RF trap

Yoshitaka Oshima, Yoshiki Moriwaki, Tadao Shimizu

Progress in Crystal Growth and Characterization of MaterialsJan 1, 19964 citations

Sympathetic cooling of fullerene ions by laser-cooled Mg+ ions in a linear rf trap

Vladimir L. Ryjkov, XianZhen Zhao, Hans A. Schuessler

A large sample $(N\ensuremath{\approx}{10}^{4})$ of fullerene ions $(m=720\phantom{\rule{0.3em}{0ex}}\mathrm{a}.\mathrm{u})$ is cooled by means of a much smaller number$(\ensuremath{\approx}100)$ of laser-cooled magnesium ions $(m=24\phantom{\rule{0.3em}{0ex}}\mathrm{a}.\mathrm{u})$ . The results demonstrate that sympathetic cooling of large molecules to low temperatures is feasible. The temperature of the $^{24}\mathrm{Mg}^{+}$ ions in the mixed ${\mathrm{Mg}}^{+}\text{\ensuremath{-}}{{\mathrm{C}}_{60}}^{+}$ ion cloud stored in an rf trap is found to be ${T}_{\mathrm{Mg}}=5\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ from their fluorescence signal. Molecular dynamics simulations are used to obtain the corresponding equilibrium temperature of the fullerene ions, and show that ${T}_{{\mathrm{C}}_{60}}=14\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ .A large sample $(N\ensuremath{\approx}{10}^{4})$ of fullerene ions $(m=720\phantom{\rule{0.3em}{0ex}}\mathrm{a}.\mathrm{u})$ is cooled by means of a much smaller number$(\ensuremath{\approx}100)$ of laser-cooled magnesium ions $(m=24\phantom{\rule{0.3em}{0ex}}\mathrm{a}.\mathrm{u})$. The results demonstrate that sympathetic cooling of large molecules to low temperatures is feasible. The temperature of the $^{24}\mathrm{Mg}^{+}$ ions in the mixed ${\mathrm{Mg}}^{+}\text{\ensuremath{-}}{{\mathrm{C}}_{60}}^{+}$ ion cloud stored in an rf trap is found to be ${T}_{\mathrm{Mg}}=5\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ from their fluorescence signal. Molecular dynamics simulations are used to obtain the corresponding equilibrium temperature of the fullerene ions, and show that ${T}_{{\mathrm{C}}_{60}}=14\phantom{\rule{0.3em}{0ex}}\mathrm{K}$.

Physical Review AAug 2, 200627 citations

Towards Non-Equilibrium Dynamics with Trapped Ions

Ariel L. Silbert, Sierra Jubin, Charlie Doret

Bulletin of the American Physical SocietyMay 25, 20160 citations

A large sample $(N\ensuremath{\approx}{10}^{4})$ of fullerene ions

(m=720\phantom{\rule{0.3em}{0ex}}\mathrm{a}.\mathrm{u})

is cooled by means of a much smaller number$(\ensuremath{\approx}100)$ of laser-cooled magnesium ions

(m=24\phantom{\rule{0.3em}{0ex}}\mathrm{a}.\mathrm{u})

. The results demonstrate that sympathetic cooling of large molecules to low temperatures is feasible. The temperature of the

^{24}\mathrm{Mg}^{+}

ions in the mixed ${\mathrm{Mg}}^{+}\text{\ensuremath{-}}{{\mathrm{C}}_{60}}^{+}$ ion cloud stored in an rf trap is found to be

{T}_{\mathrm{Mg}}=5\phantom{\rule{0.3em}{0ex}}\mathrm{K}

from their fluorescence signal. Molecular dynamics simulations are used to obtain the corresponding equilibrium temperature of the fullerene ions, and show that

{T}_{{\mathrm{C}}_{60}}=14\phantom{\rule{0.3em}{0ex}}\mathrm{K}