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 Korean Physical Society

Optical Sideband Cooling of a Radial Motional Mode of a Trapped 138Ba+ Ion

Dahyun Yum, Tarun Dutta, Jasper Phua Sing Cheng, Manas Mukherjee

Published Nov 19, 2020• 3 citations
Publisher

Abstract

The trapped ion system is one of the most promising and reliable platforms to control and study quantum mechanical phenomena and their applications. For efficient coherent manipulation of both external and internal motional states of an ion, the ion has to be in the ground state of the trapping potential. This can be achieved by resolved sideband cooling, so cooling of the motional mode is a pre-requisite. In a radially symmetric ideal linear trap, the two radial modes are often degenerate, leading to strong coupling between them and hence inefficient cooling by a single laser beam. Here, we show that by breaking the degeneracy of theradial motional modes, sideband cooling can be performed efficiently for a selected radial motional mode. We have achieved an averaged vibrational quantum number < n x > = 0.03(8) in a selected radial direction after resolved sideband cooling for a single barium ion.

DOI
10.3938/jkps.77.1143

Related papers

Efficient Raman sideband cooling of trapped ions to their motional ground state

H. Che, Ke Deng, Zhilin Xu +3 more

Efficient cooling of trapped ions is a prerequisite for various applications of the ions in precision spectroscopy, quantum information, and coherence control. Raman sideband cooling is an effective method to cool the ions to their motional ground state. We investigate both numerically and experimentally the optimization of Raman sideband cooling strategies and propose an efficient one, which can simplify the experimental setup as well as reduce the number of cooling pulses. Several cooling schemes are tested and compared through numerical simulations. The simulation result shows that the fixed-width pulses and varied-width pulses have almost the same efficiency for both the first-order and the second-order Raman sideband cooling. The optimized strategy is verified experimentally. A single ${^{25}\mathrm{Mg}}^{+}$ ion is trapped in a linear Paul trap and Raman sideband cooled, and the achieved average vibrational quantum numbers under different cooling strategies are evaluated. A good agreement between the experimental result and the simulation result is obtained.

Physical Review A•Jul 17, 2017•27 citations

Ground state cooling of the radial motion of a single ion in a penning trap and coherent manipulation of small numbers of ions

Pavel Hrmo

This thesis extends the recently reported ground state sideband cooling of the axial motion of a single ion to a broader frequency range of the axial motion, the radial motion and ion crystals. Once cold, coherent control of these different configurations is demonstrated. The experimental work in this thesis uses 40Ca+ ions that can be coherently addressed on a narrow linewidth optical transition at 729 nm. The technique of axialization that resonantly couples the two radial modes of motion is used to enhance laser Doppler cooling leading to mean phonon occupation numbers in the low hundreds for both modes. The sideband cooling technique is then used to simultaneously cool both the motional modes to within one phonon of the ground state for the first time evers. Sideband cooling is then also employed to cool the axial modes of many ion Coulomb crystals in two different configurations. For two ions in a 1D chain, motional occupation numbers of nbar_COM=0.30(4) and nbar_B=0.07(3) are achieved. For two ions in a planar 2D configuration the result for the two modes are nbar_T=nbar_COM<0.1. This technique is scaled up to demonstrate ground state occupation of up to 10 ions in the planar configuration. The axial mode of motion of a single motion is used to characterise the coherent addressing capabilities in our system through optical and motional Ramsey spectroscopy. We observe optical coherence times of 1.78(4) ms and motional coherence times of 590(12) ms. Dynamical decoupling techniques are shown to extend these coherence times. Furthermore, basic decoherence models are validated in high-lying non-thermal motional states that are prepared by a sideband heating technique. Progress towards entangling gates is demonstrated using a bichromatic laser beam to prepare non-classical states of motion.

•May 1, 2018•2 citations

Sideband cooling of ions in radio-frequency traps

E. Peik, J. Abel, Th. Becker +2 more

An experimental study of sideband laser cooling of trapped ions in miniature radio-frequency traps is presented. ${\mathrm{In}}^{+}$ ions are laser cooled by exciting the narrow intercombination line ${5s}^{2}{}^{1}{S}_{0}\ensuremath{\rightarrow}5s5p{}^{3}{P}_{1}$, which shows resolved sidebands due to the vibrational motion of the ions in the trap. The influence of the micromotion at the frequency of the oscillating trapping field is investigated. Heating processes through coupling with the trapping field occur for certain regions of negative laser detuning. A method of bichromatic sideband cooling is introduced that combines efficient cooling from high temperatures with the possibility of reaching low mean vibrational quantum numbers $〈n〉<1$ by using narrow optical transitions. This technique allows recording of high-resolution excitation spectra of the cooling transition in the Lamb-Dicke regime and thus determination of $〈n〉$. Single ions as well as two-ion Coulomb crystals have been cooled to temperatures below $100 \ensuremath{\mu}\mathrm{K}$, and population of the ground state of motion to more than 50% over long time scales is demonstrated. These values are close to the lower limit for the detection of vibrational excitation with the present method.

Physical Review A•Jul 1, 1999•90 citations

Lasing due to quantum motion of a trapped ion

Gagik Yu. Kryuchkyan, B. Kneer

We propose a simple model of an ion-trap laser: A single two-level ion confined to a harmonic trap, subjected to resolved-sideband laser cooling in the presence of external noise, and coupled strongly to an optical cavity. The lasing of the cavity mode results from the quantized treatment of the ion's motion, and occurs when the cavity is tuned to frequencies of the vibrational sidebands located below the frequency of the cooling laser.

Physical Review A•Dec 1, 1999•5 citations

Prospects for single-photon sideband cooling of optically trapped neutral atoms

Federico Berto, Elia Perego, Lucia Duca +1 more

We propose a cooling scheme for realizing single-photon sideband cooling on particles trapped in a statedependent optical potential.We develop a master rate equation from an ab initio model and find that in experimentally feasible conditions it is possible to reduce the average occupation number of the vibrational levels in one dimension by more than 90% by applying a frequency sweep on the cooling laser that sequentially cools all the motional states.Notably, this cooling scheme works also when a particle experiences a deeper trap in its internal ground state than in its excited state, a condition for which conventional single-photon sideband cooling does not work.In our analysis, we consider two cases: a two-level particle confined in an optical tweezer, and Li atoms confined in an optical lattice, and we find conditions for efficient cooling in both cases.The results from the model are confirmed by a full quantum Monte Carlo simulation of the system Hamiltonian.Our findings provide an alternative cooling scheme that can be applied in principle to any particle, e.g., atoms, molecules, or ions, confined in a state-dependent optical potential.

arXiv:2107.04110•Physical Review Research•Nov 11, 2021•5 citations

Raman sideband cooling of a 138Ba+ ion using a single Zeeman interval

Christopher M. Seck, Mark Kokish, Matthew Dietrich +1 more

Motional ground state cooling and internal state preparation are important elements for quantum logic spectroscopy (QLS), a class of quantum information processing. Since QLS does not require the high gate fidelities usually associated with quantum computation and quantum simulation, it is possible to make simplifying choices in ion species and quantum protocols at the expense of some fidelity. Here, we report sideband cooling and motional state detection protocols for $^{138}$Ba$^+$ of sufficient fidelity for QLS without an extremely narrowband laser or the use of a species with hyperfine structure. We use the two S$_{1/2}$ Zeeman sublevels of $^{138}$Ba$^+$ to Raman sideband cool a single ion to the motional ground state. Because of the small Zeeman splitting, near-resonant Raman sideband cooling of $^{138}$Ba$^+$ requires only the Doppler cooling lasers and two additional AOMs. Observing the near-resonant Raman optical pumping fluorescence, we estimate a final average motional quantum number $\bar{n}\approx0.17$. We additionally employ a second, far-off-resonant laser driving Raman $\pi$-pulses between the two Zeeman sublevels to provide motional state detection for QLS and to confirm the sideband cooling efficiency, measuring a final $\bar{n} = 0.15(6)$.

•Mar 30, 2016•0 citations
The trapped ion system is one of the most promising and reliable platforms to control and study quantum mechanical phenomena and their applications. For efficient coherent manipulation of both external and internal motional states of an ion, the ion has to be in the ground state of the trapping potential. This can be achieved by resolved sideband cooling, so cooling of the motional mode is a pre-requisite. In a radially symmetric ideal linear trap, the two radial modes are often degenerate, leading to strong coupling between them and hence inefficient cooling by a single laser beam. Here, we show that by breaking the degeneracy of theradial motional modes, sideband cooling can be performed efficiently for a selected radial motional mode. We have achieved an averaged vibrational quantum number < n x > = 0.03(8) in a selected radial direction after resolved sideband cooling for a single barium ion.
Efficient cooling of trapped ions is a prerequisite for various applications of the ions in precision spectroscopy, quantum information, and coherence control. Raman sideband cooling is an effective method to cool the ions to their motional ground state. We investigate both numerically and experimentally the optimization of Raman sideband cooling strategies and propose an efficient one, which can simplify the experimental setup as well as reduce the number of cooling pulses. Several cooling schemes are tested and compared through numerical simulations. The simulation result shows that the fixed-width pulses and varied-width pulses have almost the same efficiency for both the first-order and the second-order Raman sideband cooling. The optimized strategy is verified experimentally. A single 25Mg+{^{25}\mathrm{Mg}}^{+}25Mg+ ion is trapped in a linear Paul trap and Raman sideband cooled, and the achieved average vibrational quantum numbers under different cooling strategies are evaluated. A good agreement between the experimental result and the simulation result is obtained.
This thesis extends the recently reported ground state sideband cooling of the axial motion of a single ion to a broader frequency range of the axial motion, the radial motion and ion crystals. Once cold, coherent control of these different configurations is demonstrated. The experimental work in this thesis uses 40Ca+ ions that can be coherently addressed on a narrow linewidth optical transition at 729 nm. The technique of axialization that resonantly couples the two radial modes of motion is used to enhance laser Doppler cooling leading to mean phonon occupation numbers in the low hundreds for both modes. The sideband cooling technique is then used to simultaneously cool both the motional modes to within one phonon of the ground state for the first time evers. Sideband cooling is then also employed to cool the axial modes of many ion Coulomb crystals in two different configurations. For two ions in a 1D chain, motional occupation numbers of nbar_COM=0.30(4) and nbar_B=0.07(3) are achieved. For two ions in a planar 2D configuration the result for the two modes are nbar_T=nbar_COM<0.1. This technique is scaled up to demonstrate ground state occupation of up to 10 ions in the planar configuration. The axial mode of motion of a single motion is used to characterise the coherent addressing capabilities in our system through optical and motional Ramsey spectroscopy. We observe optical coherence times of 1.78(4) ms and motional coherence times of 590(12) ms. Dynamical decoupling techniques are shown to extend these coherence times. Furthermore, basic decoherence models are validated in high-lying non-thermal motional states that are prepared by a sideband heating technique. Progress towards entangling gates is demonstrated using a bichromatic laser beam to prepare non-classical states of motion.
An experimental study of sideband laser cooling of trapped ions in miniature radio-frequency traps is presented. In+{\mathrm{In}}^{+}In+ ions are laser cooled by exciting the narrow intercombination line ${5s}^{2}{}^{1}{S}_{0}\ensuremath{\rightarrow}5s5p{}^{3}{P}_{1}$, which shows resolved sidebands due to the vibrational motion of the ions in the trap. The influence of the micromotion at the frequency of the oscillating trapping field is investigated. Heating processes through coupling with the trapping field occur for certain regions of negative laser detuning. A method of bichromatic sideband cooling is introduced that combines efficient cooling from high temperatures with the possibility of reaching low mean vibrational quantum numbers 〈n〉<1〈n〉<1〈n〉<1 by using narrow optical transitions. This technique allows recording of high-resolution excitation spectra of the cooling transition in the Lamb-Dicke regime and thus determination of 〈n〉〈n〉〈n〉. Single ions as well as two-ion Coulomb crystals have been cooled to temperatures below $100 \ensuremath{\mu}\mathrm{K}$, and population of the ground state of motion to more than 50% over long time scales is demonstrated. These values are close to the lower limit for the detection of vibrational excitation with the present method.
We propose a cooling scheme for realizing single-photon sideband cooling on particles trapped in a statedependent optical potential.We develop a master rate equation from an ab initio model and find that in experimentally feasible conditions it is possible to reduce the average occupation number of the vibrational levels in one dimension by more than 90% by applying a frequency sweep on the cooling laser that sequentially cools all the motional states.Notably, this cooling scheme works also when a particle experiences a deeper trap in its internal ground state than in its excited state, a condition for which conventional single-photon sideband cooling does not work.In our analysis, we consider two cases: a two-level particle confined in an optical tweezer, and Li atoms confined in an optical lattice, and we find conditions for efficient cooling in both cases.The results from the model are confirmed by a full quantum Monte Carlo simulation of the system Hamiltonian.Our findings provide an alternative cooling scheme that can be applied in principle to any particle, e.g., atoms, molecules, or ions, confined in a state-dependent optical potential.
Motional ground state cooling and internal state preparation are important elements for quantum logic spectroscopy (QLS), a class of quantum information processing. Since QLS does not require the high gate fidelities usually associated with quantum computation and quantum simulation, it is possible to make simplifying choices in ion species and quantum protocols at the expense of some fidelity. Here, we report sideband cooling and motional state detection protocols for 138^{138}138Ba+^++ of sufficient fidelity for QLS without an extremely narrowband laser or the use of a species with hyperfine structure. We use the two S1/2_{1/2}1/2​ Zeeman sublevels of 138^{138}138Ba+^++ to Raman sideband cool a single ion to the motional ground state. Because of the small Zeeman splitting, near-resonant Raman sideband cooling of 138^{138}138Ba+^++ requires only the Doppler cooling lasers and two additional AOMs. Observing the near-resonant Raman optical pumping fluorescence, we estimate a final average motional quantum number nˉ≈0.17\bar{n}\approx0.17nˉ≈0.17. We additionally employ a second, far-off-resonant laser driving Raman π\piπ-pulses between the two Zeeman sublevels to provide motional state detection for QLS and to confirm the sideband cooling efficiency, measuring a final nˉ=0.15(6)\bar{n} = 0.15(6)nˉ=0.15(6).