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  • Open Access

Steering Reaction Flux by Coupling Product Channels

Dominik Dorer1, Shinsuke Haze1,2, Jing-Lun Li1, José P. D’Incao1,3,4, Eberhard Tiemann5, Paul S. Julienne1,6, Markus Deiß1, and Johannes Hecker Denschlag1,*

  • *Contact author: johannes.denschlag@uni-ulm.de
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Phys. Rev. Lett. 136, 063401 – Published 9 February, 2026

DOI: https://doi.org/10.1103/5mxs-g3z8

Abstract

We demonstrate a method for controlling the outcome of an ultracold chemical few-body reaction by redirecting a tunable fraction of reaction flux from one selected product channel to another one. In the reaction, three ultracold atoms collide to form a diatomic molecule. This product molecule can be produced in various internal states, characterizing the different product channels of the reaction. Our scheme relies on the coupling between two such product channels at an avoided molecular energy level crossing in the presence of an external magnetic field. The degree of coupling can be set by the magnetic field strength and allows for a widely tunable flux control between the two channels. This scheme is quite general and also holds great promise for a large variety of chemical processes with diverse species, since molecular energy level crossings are ubiquitous in molecular systems and are often easily accessible by standard laboratory equipment.

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References (45)

  1. K. M. Jones, E. Tiesinga, P. D. Lett, and P. S. Julienne, Ultracold photoassociation spectroscopy: Long-range molecules and atomic scattering, Rev. Mod. Phys. 78, 483 (2006).
  2. C. Chin, R. Grimm, P. Julienne, and E. Tiesinga, Feshbach resonances in ultracold gases, Rev. Mod. Phys. 82, 1225 (2010).
  3. C. H. Greene, P. Giannakeas, and J. Pérez-Ríos, Universal few-body physics and cluster formation, Rev. Mod. Phys. 89, 035006 (2017).
  4. F. Ferlaino, A. Zenesini, M. Berninger, B. Huang, H.-C. Nägerl, and R. Grimm, Efimov resonances in ultracold quantum gases, Few Body Syst. 51, 113 (2011).
  5. J. P. D’Incao, Few-body physics in resonantly interacting ultracold quantum gases, J. Phys. B 51, 043001 (2018).
  6. M. Mayle, G. Quéméner, B. P. Ruzic, and J. L. Bohn, Scattering of ultracold molecules in the highly resonant regime, Phys. Rev. A 87, 012709 (2013).
  7. J. F. E. Croft, C. Makrides, M. Li, A. Petrov, B. K. Kendrick, M. Balakrishnan, and S. Kotochigova, Universality and chaoticity in ultracold K+KRb chemical reactions, Nat. Commun. 8, 15897 (2017).
  8. P. Gersema, K. K. Voges, M. Meyer zum Alten Borgloh, L. Koch, T. Hartmann, A. Zenesini, S. Ospelkaus, J. Lin, J. He, and D. Wang, Probing photoinduced two-body loss of ultracold nonreactive bosonic Na23Rb87 and Na23K39 molecules, Phys. Rev. Lett. 127, 163401 (2021).
  9. P. D. Gregory, J. A. Blackmore, S. L. Bromley, and S. L. Cornish, Loss of ultracold Rb87Cs133 molecules via optical excitation of long-lived two-body collision complexes, Phys. Rev. Lett. 124, 163402 (2020).
  10. M.-G. Hu, Y. Liu, D. D. Grimes, Y.-W. Lin, A. H. Gheorghe, R. Vexiau, N. Bouloufa-Maafa, O. Dulieu, T. Rosenband, and K.-K. Ni, Direct observation of bimolecular reactions of ultracold KRb molecules, Science 366, 1111 (2019).
  11. R. Bause, A. Schindewolf, R. Tao, M. Duda, X.-Y. Chen, G. Quéméner, T. Karman, A. Christianen, I. Bloch, and X.-Y. Luo, Collisions of ultracold molecules in bright and dark optical dipole traps, Phys. Rev. Res. 3, 033013 (2021).
  12. M. A. Nichols, Y.-X. Liu, L. Zhu, M.-G. Hu, Y. Liu, and K.-K. Ni, Detection of long-lived complexes in ultracold atom-molecule collisions, Phys. Rev. X 12, 011049 (2022).
  13. Z. Z. Yan, J. W. Park, Y. Ni, H. Loh, S. Will, T. Karman, and M. Zwierlein, Resonant dipolar collisions of ultracold molecules induced by microwave dressing, Phys. Rev. Lett. 125, 063401 (2020).
  14. J. F. E. Croft and J. L. Bohn, Long-lived complexes and chaos in ultracold molecular collisions, Phys. Rev. A 89, 012714 (2014).
  15. L. Anderegg, S. Burchesky, Y. Bao, S. S. Yu, T. Karman, E. Chae, K.-K. Ni, W. Ketterle, and J. M. Doyle, Observation of microwave shielding of ultracold molecules, Science 373, 779 (2021).
  16. J. Lin, G. Chen, M. Jin, Z. Shi, F. Deng, W. Zhang, G. Quéméner, T. Shi, S. Yi, and D. Wang, Microwave shielding of bosonic NaRb molecules, Phys. Rev. X 13, 031032 (2023).
  17. A. Schindewolf, R. Bause, X.-Y. Chen, M. Duda, T. Karman, I. Bloch, and X.-Y. Luo, Evaporation of microwave-shielded polar molecules to quantum degeneracy, Nature (London) 607, 677 (2022).
  18. N. Bigagli, C. Warner, W. Yuan, S. Zhang, I. Stevenson, T. Karman, and S. Will, Collisionally stable gas of bosonic dipolar ground-state molecules, Nat. Phys. 19, 1579 (2023).
  19. K. Matsuda, L. De Marco, J.-R. Li, W. G. Tobias, G. Valtolina, G. Quéméner, and J. Ye, Resonant collisional shielding of reactive molecules using electric fields, Science 370, 1324 (2020).
  20. H. Son, J. J. Park, Y.-K. Lu, A. O. Jamison, T. Karman, and W. Ketterle, Control of reactive collisions by quantum interference, Science 375, 1006 (2022).
  21. H. Yang, J. Cao, Z. Su, J. Rui, B. Zhao, and J.-W. Pan, Creation of an ultracold gas of triatomic molecules from an atom–diatomic molecule mixture, Science 378, 1009 (2022).
  22. J. J. Park, Y.-K. Lu, A. O. Jamison, T. V. Tscherbul, and W. Ketterle, A Feshbach resonance in collisions between triplet ground-state molecules, Nature (London) 614, 54 (2023).
  23. X.-Y. Chen, S. Biswas, S. Eppelt, A. Schindewolf, F. Deng, T. Shi, S. Yi, T. Hilker, I. Bloch, and X.-Y. Luo, Ultracold field-linked tetratomic molecules, Nature (London) 626, 283 (2024).
  24. J. Cao, B.-Y. Wang, H. Yang, Z.-J. Fan, Z. Su, J. Rui, B. Zhao, and J.-W. Pan, Observation of photoassociation resonances in ultracold atom-molecule collisions, Phys. Rev. Lett. 132, 093403 (2024).
  25. M. Shapiro and P. Brumer, Quantum Control of Molecular Processes (Wiley-VCH, Weinheim, 2012).
  26. H. Yang, Z. Li, S. Zhang, J. L. Bohn, L. Cao, S. Zhang, G. Wang, H. Xu, and Z. Li, Channel selection of ultracold atom-molecule scattering in dynamic magnetic fields, Phys. Rev. Lett. 129, 013402 (2022).
  27. T. V. Tscherbul and R. V. Krems, Tuning bimolecular chemical reactions by electric fields, Phys. Rev. Lett. 115, 023201 (2015).
  28. R. Hermsmeier, J. Kłos, S. Kotochigova, and T. V. Tscherbul, Quantum spin state selectivity and magnetic tuning of ultracold chemical reactions of triplet alkali-metal dimers with alkali-metal atoms, Phys. Rev. Lett. 127, 103402 (2021).
  29. J. Wolf, M. Deiß, A. Krükow, E. Tiemann, B. P. Ruzic, Y. Wang, J. P. D’Incao, P. S. Julienne, and J. Hecker Denschlag, State-to-state chemistry for three-body recombination in an ultracold rubidium gas, Science 358, 921 (2017).
  30. Y. Liu, M.-G. Hu, M. A. Nichols, D. Yang, D. Xie, H. Guo, and K.-K. Ni, Precision test of statistical dynamics with state-to-state ultracold chemistry, Nature (London) 593, 379 (2021).
  31. M.-G. Hu, Y. Liu, M. A. Nichols, L. Zhu, G. Quéméner, O. Dulieu, and K.-K. Ni, Nuclear spin conservation enables state-to-state control of ultracold molecular reactions, Nat. Chem. 13, 435 (2021).
  32. Y.-X. Liu, L. Zhu, J. Luke, J. J. A. Houwman, M. C. Babin, M.-G. Hu, and K.-K. Ni, Quantum interference in atom-exchange reactions, Science 384, 1117 (2024).
  33. S. Haze, J. P. D’Incao, D. Dorer, M. Deiß, E. Tiemann, P. S. Julienne, and J. Hecker Denschlag, Spin-conservation propensity rule for three-body recombination of ultracold Rb atoms, Phys. Rev. Lett. 128, 133401 (2022).
  34. S. Haze, J.-L. Li, D. Dorer, J. P. D’Incao, P. S. Julienne, E. Tiemann, M. Deiß, and J. Hecker Denschlag, Controlling few-body reaction pathways using a Feshbach resonance, Nat. Phys. 21, 228 (2025).
  35. S. Haze, J. P. D’Incao, D. Dorer, J. Li, M. Deiß, E. Tiemann, P. S. Julienne, and J. Hecker Denschlag, Energy scaling of the product state distribution for three-body recombination of ultracold atoms, Phys. Rev. Res. 5, 013161 (2023).
  36. J. Wolf, M. Deiß, and J. Hecker Denschlag, Hyperfine magnetic substate resolved state-to-state chemistry, Phys. Rev. Lett. 123, 253401 (2019).
  37. A. Härter, A. Krükow, M. Deiß, B. Drews, E. Tiemann, and J. Hecker Denschlag, Population distribution of product states following three-body recombination in an ultracold atomic gas, Nat. Phys. 9, 512 (2013).

  38. The data for (J′=5) stem from a separate dataset measured at slightly different Rb cloud densities, resulting in ion rates and loss signals being globally different by a few percent. For an accurate comparison of the different datasets, the (J′=5) data were scaled by the corresponding factor.

  39. Magnetic fields are determined with a relative uncertainty of 1.5%.

  40. See Supplemental Material at http://link.aps.org/supplemental/10.1103/5mxs-g3z8 for details on the numerical three-body recombination calculations and on the transition matrix elements from |L⟩ and |U⟩ toward the intermediate state. This includes Refs. [33–35,41–45].
  41. H. Suno, B. D. Esry, C. H. Greene, and J. P. Burke, Three-body recombination of cold helium atoms, Phys. Rev. A 65, 042725 (2002).
  42. J. Wang, J. P. D’Incao, and C. H. Greene, Numerical study of three-body recombination for systems with many bound states, Phys. Rev. A 84, 052721 (2011).
  43. J.-L. Li, P. S. Julienne, J. Hecker Denschlag, and J. P. D’Incao, Spin hierarchy in van der Waals molecule formation via ultracold three-body recombination, Phys. Rev. A 111, 013308 (2025).
  44. J.-L. Li, P. S. Julienne, J. Hecker Denschlag, and J. P. D’Incao, Spin structure of diatomic van der Waals molecules of alkali-metal atoms, Phys. Rev. A 111, 033302 (2025).
  45. C. Strauss, T. Takekoshi, F. Lang, K. Winkler, R. Grimm, J. Hecker Denschlag, and E. Tiemann, Hyperfine, rotational, and vibrational structure of the a3Σu+ state of Rb287, Phys. Rev. A 82, 052514 (2010).

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Phys. Rev. Lett. 136, 063401– Published 9 February, 2026
  • Received 2 May 2025
  • Revised 3 November 2025
  • Accepted 19 December 2025
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