Conference on Precision Electromagnetic Measurements

Sympathetic cooling of trapped ions with resonant laser radiation [frequency standard application]

T. Shimizu, Y. Oshima, Yoshiki Moriwaki, M. Tachikawa

Published Dec 17, 2002• 0 citations

Abstract

We propose a novel model to describe dynamic properties of ions that are cooled by collisions with other laser-cooled ions in a quadrupole rf trap. The limit temperature of the sympathetic cooling is estimated as functions of the trap and laser parameters, and the mass of the ions.>

DOI: 10.1109/cpem.1994.333320

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Sympathetic cooling of trapped ions with resonant laser radiation

T. Shimizu, Yoshio Oshima, Yoshiki Moriwaki +1 more

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Conference on Precision Electromagnetic Measurements

Sympathetic cooling of trapped ions with resonant laser radiation [frequency standard application]

T. Shimizu, Y. Oshima, Yoshiki Moriwaki, M. Tachikawa

Published Dec 17, 2002• 0 citations

Publisher

Abstract

DOI: 10.1109/cpem.1994.333320

Related papers

Sympathetic cooling of trapped ions with resonant laser radiation

T. Shimizu, Yoshio Oshima, Yoshiki Moriwaki +1 more

We propose a novel model to describe dynamic properties of ions that are cooled by collisions with other laser-cooled ions in a quadrupole rf trap. The limit temperature of the sympathetic Cooling is estimated as functions of the trap and laser parameters, and the mass of the ions.

Dec 31, 19940 citations

Limiting temperature of sympathetically cooled ions in a radio-frequency trap

Taro Hasegawa, Tadao Shimizu

Physical Review AJan 29, 20037 citations

Laser cooling and sympathetic cooling in a linear quadrupole rf trap

Vladimir L. Ryjkov

An investigation of the sympathetic cooling \nmethod for the studies of large ultra-cold molecular ions in a quadrupole ion trap has been conducted.Molecular dynamics simulations are performed to study the rf heating mechanisms in the ion trap. The dependence of \nrf heating rates on the ion temperature, trapping parameters, \nand the number of ions is obtained. New rf heating mechanism \naffecting ultra-cold ion clouds exposed to laser radiation is described.The saturation spectroscopy setup of the hyperfine spectra \nof the molecular iodine has been built to provide an accurate frequency reference for the laser wavelength. This reference is used to obtain the fluorescence lineshapes of \nthe laser cooled Mg $^+$ ions under different trapping conditions.The ion temperatures are deduced from the measurements, and \nthe influence of the rf heating rates on the fluorescence lineshapes \nis also discussed. Cooling of the heavy ( $m=720$ a.u.) fullerene ions to under 10K by the means of the sympathetic cooling by the Mg $^+$ ions( $m=24$ a.u.) is demonstrated. The single-photon imaging system has been developed and used to obtain the images of the Mg $^+$ ion crystal structures at mK temperatures.An investigation of the sympathetic cooling \nmethod for the studies of large ultra-cold molecular ions in a quadrupole ion trap has been conducted.Molecular dynamics simulations are performed to study the rf heating mechanisms in the ion trap. The dependence of \nrf heating rates on the ion temperature, trapping parameters, \nand the number of ions is obtained. New rf heating mechanism \naffecting ultra-cold ion clouds exposed to laser radiation is described.The saturation spectroscopy setup of the hyperfine spectra \nof the molecular iodine has been built to provide an accurate frequency reference for the laser wavelength. This reference is used to obtain the fluorescence lineshapes of \nthe laser cooled Mg$^+$ ions under different trapping conditions.The ion temperatures are deduced from the measurements, and \nthe influence of the rf heating rates on the fluorescence lineshapes \nis also discussed. Cooling of the heavy ($m=720$a.u.) fullerene ions to under 10K by the means of the sympathetic cooling by the Mg$^+$ ions($m=24$a.u.) is demonstrated. The single-photon imaging system has been developed and used to obtain the images of the Mg$^+$ ion crystal structures at mK temperatures.

Feb 17, 20050 citations

Instability heating of sympathetically cooled ions in a linear Paul trap

T. J. Harmon, N. Moazzan-Ahmadi, R. I. Thompson

Sympathetic laser cooling of ions stored within a linear-geometry, radio frequency, electric-quadrupole trap has been investigated using computational and theoretical techniques. The simulation, which allows five sample ions to interact with 35 laser-cooled atomic ions, revealed an instability heating mechanism, which can prevent ions below a certain critical mass from being sympathetically cooled. This critical mass can, however, be varied by changing the trapping field parameters, thus allowing ions with a very large range of masses to be sympathetically cooled using a single ion species. A theoretical explanation of this instability heating mechanism is presented which predicts that the cooling-heating boundary in trapping parameter space is a line of constant ${q}_{u}$ (ion trap stability coefficient), a result supported by the computational results. The threshold value of ${q}_{u}$ depends on the masses of the interacting ions. A functional form of this dependence is given.Sympathetic laser cooling of ions stored within a linear-geometry, radio frequency, electric-quadrupole trap has been investigated using computational and theoretical techniques. The simulation, which allows five sample ions to interact with 35 laser-cooled atomic ions, revealed an instability heating mechanism, which can prevent ions below a certain critical mass from being sympathetically cooled. This critical mass can, however, be varied by changing the trapping field parameters, thus allowing ions with a very large range of masses to be sympathetically cooled using a single ion species. A theoretical explanation of this instability heating mechanism is presented which predicts that the cooling-heating boundary in trapping parameter space is a line of constant ${q}_{u}$ (ion trap stability coefficient), a result supported by the computational results. The threshold value of ${q}_{u}$ depends on the masses of the interacting ions. A functional form of this dependence is given.

arXiv:physics/0208069Physical Review AJan 31, 20037 citations

Spectral shape of in situ mass spectra of sympathetically cooled molecular ions

Takashi Baba, Izumi Waki

We formulated a model to reproduce the spectral shape of in situ mass spectra of sympathetically cooled molecular ions trapped in a linear radio-frequency-quadrupole. The molecular ions are sympathetically cooled by laser cooled ions. The mass spectrum is obtained by observing fluorescence emitted from the laser-cooled ions as we excite the resonant motion of the sympathetically cooled molecular ions in the trap. The model, which uses a pseudopotential and space-charge approach, reproduces the mass spectra of molecules. The model suggests that the variation of the space-charge density of the laser-cooled ions can produce in-trap kinetic excitation without the loss of the excited ions from the trap.We formulated a model to reproduce the spectral shape of in situ mass spectra of sympathetically cooled molecular ions trapped in a linear radio-frequency-quadrupole. The molecular ions are sympathetically cooled by laser cooled ions. The mass spectrum is obtained by observing fluorescence emitted from the laser-cooled ions as we excite the resonant motion of the sympathetically cooled molecular ions in the trap. The model, which uses a pseudopotential and space-charge approach, reproduces the mass spectra of molecules. The model suggests that the variation of the space-charge density of the laser-cooled ions can produce in-trap kinetic excitation without the loss of the excited ions from the trap.

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Resonant oscillation modes of sympathetically cooled ions in a radio-frequency trap

Taro Hasegawa, Tadao Shimizu

Sympathetic cooling of ${\mathrm{Ca}}^{+},$ ${\mathrm{Zn}}^{+},$ ${\mathrm{Sr}}^{+},$ ${\mathrm{Ba}}^{+},$ and ${\mathrm{Yb}}^{+}$ as guest ions with laser-cooled ${}^{24}{\mathrm{Mg}}^{+}$ as host ions in a rf ion trap is carried out, and resonant frequencies of their motion in the trap potential are measured. Various oscillation modes of the sympathetically cooled ions are observed. The resonant frequency of the oscillation mode is different from the frequency of either the collective oscillation frequency of the trapped ions or the oscillation frequency of each ion without host ions. This difference is well explained by a theoretical model in which coupled equations of motion of the host ion cloud with a single guest ion are considered.Sympathetic cooling of ${\mathrm{Ca}}^{+},$ ${\mathrm{Zn}}^{+},$ ${\mathrm{Sr}}^{+},$ ${\mathrm{Ba}}^{+},$ and ${\mathrm{Yb}}^{+}$ as guest ions with laser-cooled ${}^{24}{\mathrm{Mg}}^{+}$ as host ions in a rf ion trap is carried out, and resonant frequencies of their motion in the trap potential are measured. Various oscillation modes of the sympathetically cooled ions are observed. The resonant frequency of the oscillation mode is different from the frequency of either the collective oscillation frequency of the trapped ions or the oscillation frequency of each ion without host ions. This difference is well explained by a theoretical model in which coupled equations of motion of the host ion cloud with a single guest ion are considered.

Physical Review ADec 12, 200210 citations

^+

ions under different trapping conditions.The ion temperatures are deduced from the measurements, and \nthe influence of the rf heating rates on the fluorescence lineshapes \nis also discussed. Cooling of the heavy (

m=720

a.u.) fullerene ions to under 10K by the means of the sympathetic cooling by the Mg

^+

ions(

m=24

a.u.) is demonstrated. The single-photon imaging system has been developed and used to obtain the images of the Mg

^+

ion crystal structures at mK temperatures.

{q}_{u}

(ion trap stability coefficient), a result supported by the computational results. The threshold value of

{q}_{u}

depends on the masses of the interacting ions. A functional form of this dependence is given.

Sympathetic cooling of

{\mathrm{Ca}}^{+},

{\mathrm{Zn}}^{+},

{\mathrm{Sr}}^{+},

{\mathrm{Ba}}^{+},

and

{\mathrm{Yb}}^{+}

as guest ions with laser-cooled

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

as host ions in a rf ion trap is carried out, and resonant frequencies of their motion in the trap potential are measured. Various oscillation modes of the sympathetically cooled ions are observed. The resonant frequency of the oscillation mode is different from the frequency of either the collective oscillation frequency of the trapped ions or the oscillation frequency of each ion without host ions. This difference is well explained by a theoretical model in which coupled equations of motion of the host ion cloud with a single guest ion are considered.