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

Journal of the Physical Society of Japan

Controlled Extraction of Ultracold Ions from a Linear Paul Trap for Nanobeam Production

Kenji Izawa, K. Ito, H. Higaki, H. Okamoto

Published Dec 10, 2010• 19 citations
Publisher

Abstract

At ultralow temperatures near absolute zero, a small number of ions confined in a linear Paul trap align along the trap axis forming a string Coulomb crystal. The emittance of an ideal Coulomb crystal is close to zero, which implies that the Paul trap can be a unique source of extremely high quality ion beams. In this paper we address the results of proof-of-principle experiments that demonstrate the feasibility of the nondestructive extraction and acceleration of string Coulomb crystals from a conventional linear Paul trap for nanobeam production. The Doppler laser-cooling technique is employed first to crystallize a few 40 Ca + ions and, then, the DC potentials on the end electrodes are switched to launch the ions from the trap. It is confirmed that ultracold ions can be extracted without serious heating. The time interval of adjacent ions and their arrival time at the detector are controllable by changing the electrode potential. Three-dimensional multiparticle simulations are also carried out, which explain the experimental observations fairly well.

DOI
10.1143/jpsj.79.124502

Related papers

Experimental demonstration of ultrahigh-precision transport and acceleration of single ions

Kento Muroo, Kouichi Hosaka, Y. Yuri +2 more

A basic performance test of a novel ion source is carried out to attain an extremely narrow beam for pinpoint irradiation of single ions onto an intended target. In principle, the normalized root-mean-squared emittance of the beam can reach a sub-femtometer level, which makes a transverse spot size of nanometer order available. The system is based on a compact linear Paul trap equipped with a Doppler-cooling device. The trap is the most popular, economical type consisting simply of a few metal plates and rods. Among several possible choices of ion species, we picked Ca 40 + for the present investigation. A small number of Ca 40 + ions are first laser cooled to near absolute zero where they form a spatially ordered configuration called a . The axial-potential well provided by dc bias voltages on two planar electrodes is then deformed gradually to eject the ions from the trap along the design orbit. We demonstrate that it is possible to launch the ultracold ions one by one at arbitrary timing with no serious radio-frequency heating. These ions are accelerated to 1 keV immediately after the extraction. The effectiveness of a few different ion-ejection schemes is experimentally verified and supported by three-dimensional molecular dynamics simulations.

Physical Review Accelerators and Beams•Apr 3, 2026•0 citations

Research and development of an ultrahigh-precision single-ion implanter

Yuri Yosuke, Hosaka Koichi, Miyawaki Nobumasa +8 more

Ion implantation is an accelerator-based technology used to create defects and introducing impurities into solid materials. A research and development study is currently underway toward ultrahigh-precision single-ion implantation using laser-cooling techniques at Takasaki Institute, National Institutes for Quantum Science and Technology. To achieve this, we incorporate a linear Paul trap as an ultracold single-ion source, where trapped ions can be made “Coulomb-crystallized” through Doppler laser cooling. In our scheme, nitrogen or silicon ions, useful for ion implantation to create color centers in materials, are sympathetically cooled through Coulomb collisions by co-trapping them with laser-cooled calcium ions to form a two-component crystal. These cold ions are then selectively extracted from the trap to be accelerated and focused through a 50-kV electrostatic bipotential-lens system. Our goal is to achieve beam focusing for ultrahigh-precision implantation on the order of 10 nm. The implanter system has already been assembled, and the commissioning is currently ongoing to enable single-ion extraction using a Coulomb crystal. In these proceedings, we describe the scheme for selective ion extraction and nanobeam focusing based on multiparticle simulations and briefly report recent progress in system implementation.

•May 1, 2026•0 citations

Research and Development of an Ultrahigh Precision Single Ion Implanter

Yosuke Yuri, Kouichi Hosaka, Nobumasa Miyawaki +9 more

Ion implantation is an accelerator technology essential for creating defects or introducing impurities into materials. A research and development study is currently underway at QST Takasaki Institute toward ultrahigh-precision single-ion implantation based on laser-cooling techniques. To achieve this, we incorporate a linear Paul trap as an ultracold single-ion source, where trapped ions can be cooled to the order of mK or even “Coulomb-crystallized” by Doppler laser cooling. In our scheme, N or Si ions, useful for ion implantation to create color centers, are sympathetically cooled down to the mK range through Coulomb collisions by co-trapping them with laser-cooled Ca ions. Then, the ions are extracted selectively from the trap to be accelerated and focused through a 50-kV electrostatic bipotential lens system. We aim to focus the ions on the order of 10 nm for ultrahigh-precision implantation. The implantation system has already been assembled, and the commissioning is currently underway to enable ion extraction using a Coulomb crystal and focusing extracted cold ions. We present the status of system development and outline the scheme for selective ion extraction and nanobeam focusing based on multiparticle simulations.

JACOW•Nov 28, 2025•0 citations

Simulation study of ultrahigh-precision single-ion extraction from a linear Paul trap

Kento Muroo, H. Okamoto, Nobumasa Miyawaki +1 more

Abstract A detailed simulation study is conducted to explore the possibility of transporting a single ion precisely along a particular design orbit. As a practically useful example, we consider nitrogen ions sympathetically cooled with ultracold calcium ions produced in a linear Paul trap (LPT) by the Doppler laser-cooling technique. A single nitrogen almost completely frozen in the laboratory frame is extracted from the LPT by manipulating the axial potential barriers. A similar idea was recently implemented by Groot-Berning et al. [New J. Phys. 23, 063067 (2021)] to create nitrogen-vacancy centers in diamond as a platform for some important quantum technologies. We here perform systematic 3D simulations taking a standard LPT structure into account and figure out the necessary conditions to achieve the ultrahigh-precision irradiation of a single nitrogen onto any target. In addition to the string Coulomb crystal used in the previous work above, we show that even the shell crystalline structure can be employed for our purpose. When several specific conditions are satisfied, a normalized root-mean-squared emittance of ejected nitrogen ions can be made of the order of 10−16 m·rad in transverse dimensions perpendicular to the design orbit.

Progress of Theoretical and Experimental Physics•Jun 1, 2023•6 citations

Characterization of ion Coulomb crystals in a linear Paul trap

K. Okada, M. Wada, Toshiyuki Takayanagi +2 more

We describe a simple and fast method for simulating observed images of ion Coulomb crystals. In doing so, cold elastic collisions between Coulomb crystals and virtual very light atoms are implemented in a molecular dynamics (MD) simulation code. Such an approach reproduces the observed images of Coulomb crystals by obtaining density plots of the statistics of existence of each ion. The simple method has the advantage of short computing time in comparison with previous calculation methods. As a demonstration of the simulation, the formation of a planar Coulomb crystal with a small number of ions has been investigated in detail in a linear ion trap both experimentally and by simulation. However, also large Coulomb crystals including up to 1400 ions have been photographed and simulated to extract the secular temperature and the number of ions. For medium-sized crystals, a comparison between experiments and calculations has been performed. Moreover, an MD simulation of the sympathetic cooling of small molecular ions was performed in order to test the possibility of extracting the temperature and the number of refrigerated molecular ions from crystal images of laser-cooled ions. Such information is basic to studying ultracold ion-molecule reactions using ion Coulomb crystals including sympathetically cooled molecular ions.

Physical Review A•Jan 28, 2010•52 citations

Sympathetic cooling and crystallization of ions in a linear Paul trap

Michael Drewsen, Paul David Bowe, Liv Hornekær +3 more

Coulomb crystals, containing up to a few hundred ions of which more than 50% were cooled sympathetically by the Coulomb interaction with laser cooled Mg+ ions, have been produced in a linear Paul trap. By controlling the balance of the radiation pressure from the two cooling lasers, the Coulomb crystals could be segregated according to ion species. Previous studies of ion crystals and molecular dynamics simulations suggest that the temperature may be around 10 mK or lower. The obtained results indicate that a wide range of atomic and molecular ions, which due to their internal structures are not amenable to direct laser cooling, can be effectively cooled and localized (crystallized) in linear Paul traps. For high resolution spectroscopy of such ions this may turn out to be very useful.

AIP conference proceedings•Jan 1, 1999•0 citations
At ultralow temperatures near absolute zero, a small number of ions confined in a linear Paul trap align along the trap axis forming a string Coulomb crystal. The emittance of an ideal Coulomb crystal is close to zero, which implies that the Paul trap can be a unique source of extremely high quality ion beams. In this paper we address the results of proof-of-principle experiments that demonstrate the feasibility of the nondestructive extraction and acceleration of string Coulomb crystals from a conventional linear Paul trap for nanobeam production. The Doppler laser-cooling technique is employed first to crystallize a few 40 Ca + ions and, then, the DC potentials on the end electrodes are switched to launch the ions from the trap. It is confirmed that ultracold ions can be extracted without serious heating. The time interval of adjacent ions and their arrival time at the detector are controllable by changing the electrode potential. Three-dimensional multiparticle simulations are also carried out, which explain the experimental observations fairly well.
A basic performance test of a novel ion source is carried out to attain an extremely narrow beam for pinpoint irradiation of single ions onto an intended target. In principle, the normalized root-mean-squared emittance of the beam can reach a sub-femtometer level, which makes a transverse spot size of nanometer order available. The system is based on a compact linear Paul trap equipped with a Doppler-cooling device. The trap is the most popular, economical type consisting simply of a few metal plates and rods. Among several possible choices of ion species, we picked Ca 40 + for the present investigation. A small number of Ca 40 + ions are first laser cooled to near absolute zero where they form a spatially ordered configuration called a . The axial-potential well provided by dc bias voltages on two planar electrodes is then deformed gradually to eject the ions from the trap along the design orbit. We demonstrate that it is possible to launch the ultracold ions one by one at arbitrary timing with no serious radio-frequency heating. These ions are accelerated to 1 keV immediately after the extraction. The effectiveness of a few different ion-ejection schemes is experimentally verified and supported by three-dimensional molecular dynamics simulations.
Ion implantation is an accelerator-based technology used to create defects and introducing impurities into solid materials. A research and development study is currently underway toward ultrahigh-precision single-ion implantation using laser-cooling techniques at Takasaki Institute, National Institutes for Quantum Science and Technology. To achieve this, we incorporate a linear Paul trap as an ultracold single-ion source, where trapped ions can be made “Coulomb-crystallized” through Doppler laser cooling. In our scheme, nitrogen or silicon ions, useful for ion implantation to create color centers in materials, are sympathetically cooled through Coulomb collisions by co-trapping them with laser-cooled calcium ions to form a two-component crystal. These cold ions are then selectively extracted from the trap to be accelerated and focused through a 50-kV electrostatic bipotential-lens system. Our goal is to achieve beam focusing for ultrahigh-precision implantation on the order of 10 nm. The implanter system has already been assembled, and the commissioning is currently ongoing to enable single-ion extraction using a Coulomb crystal. In these proceedings, we describe the scheme for selective ion extraction and nanobeam focusing based on multiparticle simulations and briefly report recent progress in system implementation.
Ion implantation is an accelerator technology essential for creating defects or introducing impurities into materials. A research and development study is currently underway at QST Takasaki Institute toward ultrahigh-precision single-ion implantation based on laser-cooling techniques. To achieve this, we incorporate a linear Paul trap as an ultracold single-ion source, where trapped ions can be cooled to the order of mK or even “Coulomb-crystallized” by Doppler laser cooling. In our scheme, N or Si ions, useful for ion implantation to create color centers, are sympathetically cooled down to the mK range through Coulomb collisions by co-trapping them with laser-cooled Ca ions. Then, the ions are extracted selectively from the trap to be accelerated and focused through a 50-kV electrostatic bipotential lens system. We aim to focus the ions on the order of 10 nm for ultrahigh-precision implantation. The implantation system has already been assembled, and the commissioning is currently underway to enable ion extraction using a Coulomb crystal and focusing extracted cold ions. We present the status of system development and outline the scheme for selective ion extraction and nanobeam focusing based on multiparticle simulations.
Abstract A detailed simulation study is conducted to explore the possibility of transporting a single ion precisely along a particular design orbit. As a practically useful example, we consider nitrogen ions sympathetically cooled with ultracold calcium ions produced in a linear Paul trap (LPT) by the Doppler laser-cooling technique. A single nitrogen almost completely frozen in the laboratory frame is extracted from the LPT by manipulating the axial potential barriers. A similar idea was recently implemented by Groot-Berning et al. [New J. Phys. 23, 063067 (2021)] to create nitrogen-vacancy centers in diamond as a platform for some important quantum technologies. We here perform systematic 3D simulations taking a standard LPT structure into account and figure out the necessary conditions to achieve the ultrahigh-precision irradiation of a single nitrogen onto any target. In addition to the string Coulomb crystal used in the previous work above, we show that even the shell crystalline structure can be employed for our purpose. When several specific conditions are satisfied, a normalized root-mean-squared emittance of ejected nitrogen ions can be made of the order of 10−16 m·rad in transverse dimensions perpendicular to the design orbit.
We describe a simple and fast method for simulating observed images of ion Coulomb crystals. In doing so, cold elastic collisions between Coulomb crystals and virtual very light atoms are implemented in a molecular dynamics (MD) simulation code. Such an approach reproduces the observed images of Coulomb crystals by obtaining density plots of the statistics of existence of each ion. The simple method has the advantage of short computing time in comparison with previous calculation methods. As a demonstration of the simulation, the formation of a planar Coulomb crystal with a small number of ions has been investigated in detail in a linear ion trap both experimentally and by simulation. However, also large Coulomb crystals including up to 1400 ions have been photographed and simulated to extract the secular temperature and the number of ions. For medium-sized crystals, a comparison between experiments and calculations has been performed. Moreover, an MD simulation of the sympathetic cooling of small molecular ions was performed in order to test the possibility of extracting the temperature and the number of refrigerated molecular ions from crystal images of laser-cooled ions. Such information is basic to studying ultracold ion-molecule reactions using ion Coulomb crystals including sympathetically cooled molecular ions.
Coulomb crystals, containing up to a few hundred ions of which more than 50% were cooled sympathetically by the Coulomb interaction with laser cooled Mg+ ions, have been produced in a linear Paul trap. By controlling the balance of the radiation pressure from the two cooling lasers, the Coulomb crystals could be segregated according to ion species. Previous studies of ion crystals and molecular dynamics simulations suggest that the temperature may be around 10 mK or lower. The obtained results indicate that a wide range of atomic and molecular ions, which due to their internal structures are not amenable to direct laser cooling, can be effectively cooled and localized (crystallized) in linear Paul traps. For high resolution spectroscopy of such ions this may turn out to be very useful.