- Physical Review Journals
All JournalsPhysics Magazine

Physical Review A

Reuse & Permissions

It is not necessary to obtain permission to reuse this article or its components as it is available under the terms of the Creative Commons Attribution 4.0 International license. This license permits unrestricted use, distribution, and reproduction in any medium, provided attribution to the author(s) and the published article's title, journal citation, and DOI are maintained. Please note that some figures may have been included with permission from other third parties. It is your responsibility to obtain the proper permission from the rights holder directly for these figures.

Export citation

Export citation

Choose format for download:

Download Citation
  • Letter
  • Open Access

Coulomb crystallization of xenon highly charged ions in a laser-cooled Ca+ matrix

Leonid Prokhorov1, Aaron A. Smith1, Mingyao Xu1, Kostas Georgiou1,2, Vera Guarrera1, Lakshmi P. Kozhiparambil Sajith2,3,4, Elwin A. Dijck2, Christian Warnecke2,3,4, Malte Wehrheim5 et al.

Alexander Wilzewski5,*, Laura Blackburn6, Matthias Keller6, Vincent Boyer1, Thomas Pfeifer2, Ullrich Schwanke3, Cigdem Issever3,4, Steven Worm3,4, Piet O. Schmidt5,7, José R. Crespo López-Urrutia2, and Giovanni Barontini1,†

  • *Present address: Max-Planck-Institute for Quantum Optics, 85748 Garching, Germany.
  • †Contact author: g.barontini@bham.ac.uk
PDF

Phys. Rev. A 113, L041102 – Published 15 April, 2026

DOI: https://doi.org/10.1103/lxr8-l7wq

Abstract

We report the sympathetic cooling and Coulomb crystallization of xenon highly charged ions (HCIs) with laser-cooled Ca+ ions. The HCIs are produced in a compact electron beam ion trap, then charge selected, decelerated, and finally injected into a cryogenic linear Paul trap. There, they are captured into Ca+40 Coulomb crystals, and cocrystallized within them, causing dark voids in their fluorescence images. Fine control over the number of trapped ions and HCIs allows us to realize mixed-species crystals with arbitrary ordering patterns. By investigating Xeq+−Ca+ strings, we confirm the HCI charge states, measure their lifetime, and characterize the mixed-species motional modes. Our system effectively combines the established quantum control toolbox for Ca+ with the rich set of atomic properties of Xe highly charged ions, providing a resourceful platform for optical frequency metrology, searches for signatures of new physics, and quantum information science.

View figure in article

Physics Subject Headings (PhySH)

Article Text

References (55)

  1. M. S. Safronova, D. Budker, D. DeMille, D. F. J. Kimball, A. Derevianko, and C. W. Clark, Search for new physics with atoms, molecules, and nuclei, Rev. Mod. Phys. 90, 025008 (2018).
  2. M. G. Kozlov, M. S. Safronova, J. R. C. López-Urrutia, and P. O. Schmidt, Highly charged ions: Optical clocks and applications in fundamental physics, Rev. Mod. Phys. 90, 045005 (2018).
  3. V. A. Dzuba and V. V. Flambaum, Highly charged ions for atomic clocks and search for variation of the fine-structure constant, Hyperfine Interact. 236, 79 (2015).
  4. S. Schiller, Hydrogenlike highly charged ions for tests of the time independence of fundamental constants, Phys. Rev. Lett. 98, 180801 (2007).
  5. J. Berengut, V. Dzuba, and V. Flambaum, Enhanced laboratory sensitivity to variation of the fine-structure constant using highly charged ions, Phys. Rev. Lett. 105, 120801 (2010).
  6. J. C. Berengut, V. A. Dzuba, V. V. Flambaum, and A. Ong, Optical transitions in highly charged californium ions with high sensitivity to variation of the fine-structure constant, Phys. Rev. Lett. 109, 070802 (2012).
  7. S. G. Porsev, U. I. Safronova, M. S. Safronova, P. O. Schmidt, A. I. Bondarev, M. G. Kozlov, I. I. Tupitsyn, and C. Cheung, Optical clocks based on the Cf15+ and Cf17+ ions, Phys. Rev. A 102, 012802 (2020).
  8. G. Barontini, L. Blackburn, V. Boyer, F. Butuc-Mayer, X. Calmet, J. C. Lopez-Urrutia, E. Curtis, B. Darquié, J. Dunningham, N. Fitch, et al., Measuring the stability of fundamental constants with a network of clocks, EPJ Quantum Technol. 9, 12 (2022).
  9. R. Shaniv, R. Ozeri, M. S. Safronova, S. G. Porsev, V. A. Dzuba, V. V. Flambaum, and H. Häffner, New methods for testing Lorentz invariance with atomic systems, Phys. Rev. Lett. 120, 103202 (2018).
  10. N. Sherrill, A. O. Parsons, C. F. A. Baynham, W. Bowden, E. A. Curtis, R. Hendricks, I. R. Hill, R. Hobson, H. S. Margolis, B. I. Robertson, M. Schioppo, K. Szymaniec, A. Tofful, J. Tunesi, R. M. Godun, and X. Calmet, Analysis of atomic-clock data to constrain variations of fundamental constants, New J. Phys. 25, 093012 (2023).
  11. K. Beloy, M. I. Bodine, T. Bothwell, S. M. Brewer, S. L. Bromley, J.-S. Chen, J.-D. Deschênes, S. A. Diddams, R. J. Fasano, T. M. Fortier, Y. S. Hassan, D. B. Hume, D. Kedar, C. J. Kennedy, I. Khader, A. Koepke, D. R. Leibrandt, H. Leopardi, A. D. Ludlow, W. F. McGrew, et al., Frequency ratio measurements at 18-digit accuracy using an optical clock network, Nature (London) 591, 564 (2021).
  12. M. Filzinger, S. Dörscher, R. Lange, J. Klose, M. Steinel, E. Benkler, E. Peik, C. Lisdat, and N. Huntemann, Improved limits on the coupling of ultralight bosonic dark matter to photons from optical atomic clock comparisons, Phys. Rev. Lett. 130, 253001 (2023).
  13. L. Gruber, J. P. Holder, J. Steiger, B. R. Beck, H. E. DeWitt, J. Glassman, J. W. McDonald, D. A. Church, and D. Schneider, Evidence for highly charged ion Coulomb crystallization in multicomponent strongly coupled plasmas, Phys. Rev. Lett. 86, 636 (2001).
  14. J. P. Holder, L. Gruber, D. A. Church, and D. Schneider, Cold highly charged ions in a Penning trap: Experiment and simulation, AIP Conf. Proc. 606, 164 (2002).
  15. L. Schmöger, O. O. Versolato, M. Schwarz, M. Kohnen, A. Windberger, B. Piest, S. Feuchtenbeiner, J. Pedregosa-Gutierrez, T. Leopold, P. Micke, A. K. Hansen, M. Drewsen, J. Ullrich, P. O. Schmidt, and J. R. C. López-Urrutia, Coulomb crystallization of highly charged ions, Science 347, 1233 (2015).
  16. P. Micke, T. Leopold, S. A. King, E. Benkler, L. J. Spieß, L. Schöger, M. Schwarz, J. R. C. López-Urrutia, and P. O. Schmidt, Coherent laser spectroscopy of highly charged ions using quantum logic, Nature (London) 578, 60 (2020).
  17. S. A. King, L. J. Spieß, P. Micke, A. Wilzewski, T. Leopold, E. Benkler, R. Lange, N. Huntemann, A. Surzhykov, V. A. Yerokhin, J. R. C. López-Urrutia, and P. O. Schmidt, An optical atomic clock based on a highly charged ion, Nature (London) 611, 43 (2022).
  18. A. Wilzewski, L. J. Spieß, M. Wehrheim, S. Chen, S. A. King, P. Micke, M. Filzinger, M. R. Steinel, N. Huntemann, E. Benkler, P. O. Schmidt, L. I. Huber, J. Flannery, R. Matt, M. Stadler, R. Oswald, F. Schmid, D. Kienzler, J. Home, D. P. L. A. Craik, et al., Nonlinear calcium King plot constrains new bosons and nuclear properties, Phys. Rev. Lett. 134, 233002 (2025).
  19. L. J. Spieß, S. Chen, A. Wilzewski, M. Wehrheim, J. Gilles, A. Surzhykov, E. Benkler, M. Filzinger, M. Steinel, N. Huntemann, C. Cheung, S. G. Porsev, A. I. Bondarev, M. S. Safronova, J. R. C. López-Urrutia, and P. O. Schmidt, Excited-state magnetic properties of carbon-like Ca14+, Phys. Rev. Lett. 135, 043002 (2025).
  20. S. Chen, L. J. Spieß, A. Wilzewski, M. Wehrheim, K. Dietze, I. Vybornyi, K. Hammerer, J. R. C. López-Urrutia, and P. O. Schmidt, Identification of highly forbidden optical transitions in highly charged ions, Phys. Rev. Appl. 22, 054059 (2024).
  21. C. Cheung, S. G. Porsev, D. Filin, M. S. Safronova, M. Wehrheim, L. J. Spieß, S. Chen, A. Wilzewski, J. R. C. López-Urrutia, and P. O. Schmidt, Finding the ultranarrow P32→P30 electric quadrupole transition in Ni12+ ion for an optical clock, Phys. Rev. Lett. 135, 093002 (2025).
  22. S.-L. Chen, Z.-q. Zhou, G.-s. Zhang, J. Xiao, Y. Huang, K.-L. Gao, and H. Guan, Coulomb crystallization of highly charged Ni12+ ions in a linear Paul trap, Phys. Rev. A 112, 063115 (2025).
  23. N.-H. Rehbehn, M. K. Rosner, J. C. Berengut, P. O. Schmidt, T. Pfeifer, M. F. Gu, and J. R. C. López-Urrutia, Narrow and ultranarrow transitions in highly charged Xe ions as probes of fifth forces, Phys. Rev. Lett. 131, 161803 (2023).
  24. J. C. Berengut, C. Delaunay, A. Geddes, and Y. Soreq, Generalized King linearity and new physics searches with isotope shifts, Phys. Rev. Res. 2, 043444 (2020).
  25. Y. Huang, H. Guan, P. Liu, W. Bian, L. Ma, K. Liang, T. Li, and K. Gao, Evaluation of the systematic shifts of a single-Ca+40-ion frequency standard, Phys. Rev. A 84, 053841 (2011).
  26. B.-l. Zhang, Z.-x. Ma, Y. Huang, H.-l. Han, R.-m. Hu, Y.-z. Wang, H.-q. Zhang, L.-y. Tang, T.-y. Shi, H. Guan, and K.-l. Gao, Liquid-nitrogen-cooled ​Ca+40 ion optical clock with a systematic uncertainty of ​4.4×10−19, Phys. Rev. Lett. 136, 053202 (2026).
  27. C. D. Marciniak, T. Feldker, I. Pogorelov, R. Kaubruegger, D. V. Vasilyev, R. van Bijnen, P. Schindler, P. Zoller, R. Blatt, and T. Monz, Optimal metrology with programmable quantum sensors, Nature (London) 603, 604 (2022).
  28. I. Pogorelov, T. Feldker, Ch. D. Marciniak, L. Postler, G. Jacob, O. Krieglsteiner, V. Podlesnic, M. Meth, V. Negnevitsky, M. Stadler, B. Höfer, C. Wächter, K. Lakhmanskiy, R. Blatt, P. Schindler, and T. Monz, Compact ion-trap quantum computing demonstrator, PRX Quantum 2, 020343 (2021).
  29. X. Tong, A. H. Winney, and S. Willitsch, Sympathetic cooling of molecular ions in selected rotational and vibrational states produced by threshold photoionization, Phys. Rev. Lett. 105, 143001 (2010).
  30. C.-W. Chou, C. Kurz, D. B. Hume, P. N. Plessow, D. R. Leibrandt, and D. Leibfried, Preparation and coherent manipulation of pure quantum states of a single molecular ion, Nature (London) 545, 203 (2017).
  31. O. Krohn, K. Catani, S. P. Sundar, J. Greenberg, G. da Silva, and H. Lewandowski, Reactions of acetonitrile with trapped, translationally cold acetylene cations, J. Phys. Chem. A 127, 5120 (2023).
  32. M. Drewsen, Ion Coulomb crystals, Physica B 460, 105 (2015).
  33. L. Blackburn and M. Keller, The effect of the electric trapping field on state-selective loading of molecules into RF ion traps, Sci. Rep. 10, 18449 (2020).
  34. L. Blackburn, A. Shepherd, and M. Keller, Fast switching of the RF trapping field in an ion trap, New J. Phys. 27, 045001 (2025).
  35. N. B. Khanyile, G. Shu, and K. R. Brown, Observation of vibrational overtones by single-molecule resonant photodissociation, Nat. Commun. 6, 7825 (2015).
  36. R. Rugango, J. E. Goeders, T. H. Dixon, J. M. Gray, N. Khanyile, G. Shu, R. J. Clark, and K. R. Brown, Sympathetic cooling of molecular ion motion to the ground state, New J. Phys. 17, 035009 (2015).
  37. K. Okada, M. Ichikawa, M. Wada, and H. A. Schuessler, Quasiequilibrium characterization of mixed-ion Coulomb crystals, Phys. Rev. Appl. 4, 054009 (2015).
  38. L. Petralia, A. Tsikritea, J. Loreau, T. Softley, and B. Heazlewood, Strong inverse kinetic isotope effect observed in ammonia charge exchange reactions, Nat. Commun. 11, 173 (2020).
  39. M. Guggemos, D. Heinrich, O. Herrera-Sancho, R. Blatt, and C. Roos, Sympathetic cooling and detection of a hot trapped ion by a cold one, New J. Phys. 17, 103001 (2015).
  40. M. Schwarz, O. O. Versolato, A. Windberger, F. R. Brunner, T. Ballance, S. N. Eberle, J. Ullrich, P. O. Schmidt, A. K. Hansen, A. D. Gingell, M. Drewsen, and J. R. C. López-Urrutia, Cryogenic linear Paul trap for cold highly charged ion experiments, Rev. Sci. Instrum. 83, 083115 (2012).
  41. L. Schmöger, M. Schwarz, T. M. Baumann, O. O. Versolato, B. Piest, T. Pfeifer, J. Ullrich, P. O. Schmidt, and J. R. C. López-Urrutia, Deceleration, precooling, and multi-pass stopping of highly charged ions in Be+ Coulomb crystals, Rev. Sci. Instrum. 86, 103111 (2015).
  42. P. Micke, S. Kühn, L. Buchauer, J. R. Harries, T. M. Bücking, K. Blaum, A. Cieluch, A. Egl, D. Hollain, S. Kraemer, T. Pfeifer, P. O. Schmidt, R. X. Schüssler, C. Schweiger, T. Stöhlker, S. Sturm, R. N. Wolf, S. Bernitt, and J. R. C. López-Urrutia, The Heidelberg compact electron beam ion traps, Rev. Sci. Instrum. 89, 063109 (2018).
  43. P. Micke, J. Stark, S. A. King, T. Leopold, T. Pfeifer, L. Schmöger, M. Schwarz, L. J. Spieß, P. O. Schmidt, and J. R. C. López-Urrutia, Closed-cycle, low-vibration 4 K cryostat for ion traps and other applications, Rev. Sci. Instrum. 90, 065104 (2019).
  44. T. Leopold, S. A. King, P. Micke, A. Bautista-Salvador, J. C. Heip, C. Ospelkaus, J. R. C. López-Urrutia, and P. O. Schmidt, A cryogenic radio-frequency ion trap for quantum logic spectroscopy of highly charged ions, Rev. Sci. Instrum. 90, 073201 (2019).
  45. E. A. Dijck, C. Warnecke, M. Wehrheim, R. B. Henninger, J. Eff, K. Georgiou, A. Graf, S. Kokh, L. P. Kozhiparambil Sajith, C. Mayo, V. M. Schaefer, C. Volk, P. O. Schmidt, T. Pfeifer, and J. R. C. López-Urrutia, Sympathetically cooled highly charged ions in a radio-frequency trap with superconducting magnetic shielding, Rev. Sci. Instrum. 94, 083203 (2023).
  46. G. Sikler, J. R. C. López-Urrutia, J. Dilling, S. Epp, C. Osborne, and J. Ullrich, A high-current EBIT for charge-breeding of radionuclides for the TITAN spectrometer, Eur. Phys. J. A 25, 63 (2005).
  47. P. Mandal, G. Sikler, and M. Mukherjee, Simulation study and analysis of a compact Einzel lens-deflector for low energy ion beam, J. Instrum. 6, P02004 (2011).
  48. No active isotope separation is implemented prior to trap injection in the present work; the loaded ions therefore reflect the natural isotopic mixture.
  49. L.-A. Rüffert, E. A. Dijck, L. Timm, J. R. C. López-Urrutia, and T. E. Mehlstäubler, Domain formation and structural stabilities in mixed-species Coulomb crystals induced by sympathetically cooled highly charged ions, Phys. Rev. A 110, 063110 (2024).
  50. J. P. Home, in Advances in Atomic, Molecular, and Optical Physics, Vol. 62, edited by E. Arimondo, P. R. Berman, and C. C. Lin (Academic Press, New York, 2012), Chap. 4, pp. 231–277.
  51. K. Gao, The Ca+40 ion optical clock, Natl. Sci. Rev. 7, 1799 (2020).
  52. S. A. King, L. J. Spieß, P. Micke, A. Wilzewski, T. Leopold, J. R. C. López-Urrutia, and P. O. Schmidt, Algorithmic ground-state cooling of weakly coupled oscillators using quantum logic, Phys. Rev. X 11, 041049 (2021).
  53. T. R. Tan, J. P. Gaebler, Y. Lin, Y. Wan, R. Bowler, D. Leibfried, and D. J. Wineland, Multi-element logic gates for trapped-ion qubits, Nature (London) 528, 380 (2015).
  54. C. D. Bruzewicz, R. McConnell, J. Stuart, J. M. Sage, and J. Chiaverini, Dual-species, multi-qubit logic primitives for Ca+/Sr+ trapped-ion crystals, npj Quantum Inf. 5, 102 (2019).
  55. G. Barontini, Coulomb crystallization of xenon highly charged ions in a laser-cooled Ca+ matrix [Data set], Zenodo (2026), https://doi.org/10.5281/zenodo.19237681.

Outline

Information

Phys. Rev. A 113, L041102– Published 15 April, 2026
  • Received 13 December 2025
  • Accepted 26 March 2026
Crossmark - Check for updates button
Creative Commons Logo

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

Published by the American Physical Society

Sign In to Your Journals Account

Filter

Filter

Article Lookup

Enter a citation