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Indirect Cooling of Weakly Coupled Trapped-Ion Mechanical Oscillators



Panyu Hou, Jenny Wu, Stephen Erickson, Giorgio Zarantonello, Adam Brandt, Daniel Cole, Andrew C. Wilson, Daniel Slichter, Dietrich Leibfried


Cooling the motion of trapped ions to near the quantum ground state is crucial for many ap- plications in quantum information processing and quantum metrology. However, some motional modes of trapped ions are difficult to cool because they only interact weakly, or not at all, with the radiation used for cooling, typically from laser beams. We overcome these obstacles by coupling a mode with weak or zero cooling radiation interaction to one with strong cooling radiation interaction using parametric modulation of the trapping potential, thereby enabling indirect cooling of the first mode. In this way, we demonstrate near-ground-state cooling of motional modes with weak or zero cooling radiation interaction in two-ion and three-ion crystals of the same and mixed ion species, specifically 9Be+-9Be+, 9Be+-25Mg+, and 9Be+-25Mg+-9Be+ crystals. The approach is generally applicable to any Coulomb crystal where some but not all modes are efficiently cooled, including crystals containing molecular ions, highly-charged ions, charged fundamental particles, or charged macroscopic objects.
Physical Review X


Trapped ions, Ground-state cooling, Coupled harmonic oscillators, Quantum information processing, Quantum Metrology.


Hou, P. , Wu, J. , Erickson, S. , Zarantonello, G. , Brandt, A. , Cole, D. , Wilson, A. , Slichter, D. and Leibfried, D. (2024), Indirect Cooling of Weakly Coupled Trapped-Ion Mechanical Oscillators, Physical Review X, [online],, (Accessed June 17, 2024)


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Created April 2, 2024, Updated June 7, 2024