Stabilization of three-body resonances to bound states in a continuum
Pith reviewed 2026-05-23 01:10 UTC · model grok-4.3
The pith
Three-body resonances can be stabilized into non-decaying bound states in the continuum by continuous tuning of parameters in a two-channel model.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
Within a two-channel approach we unveil the underlying mechanism and show how the lifetime can be made infinitely long by a continuous tuning of system parameters. The validity of the theory is illustrated in two different examples: a mass-imbalanced system in one dimension and a system of three identical bosons in three dimensions, relevant to Efimov physics, where one tunable parameter is an external magnetic field.
What carries the argument
The two-channel model that isolates the resonance width and allows it to be tuned continuously to zero.
If this is right
- The stabilization occurs for mass-imbalanced systems in one dimension.
- The stabilization occurs for three identical bosons in three dimensions and can be achieved by tuning an external magnetic field.
- The same stabilization effect is expected to apply to a wide range of other unstable few-body systems.
- The approach opens new perspectives for fundamental studies and technical applications of controlled few-body states.
Where Pith is reading between the lines
- Cold-atom experiments could realize the predicted states by scanning magnetic field values around the predicted stabilization point.
- The mechanism may connect to stabilization techniques already used for two-body resonances in the same experimental platforms.
- If the width can be tuned through zero, nearby parameter values may allow controlled finite lifetimes for studies of resonance decay.
Load-bearing premise
The two-channel model includes every relevant decay channel so the resonance width can reach exactly zero without extra channels or corrections preventing it.
What would settle it
A calculation or measurement in either the one-dimensional mass-imbalanced case or the three-dimensional boson case showing that the resonance width remains finite at the parameter value where the two-channel model predicts zero width.
Figures
read the original abstract
Three-body resonances are ubiquitous in quantum few-body physics and are characterized by a finite lifetime before decaying into continuum states of their composing subsystems. In this work we present a theoretical study on the possibility to stabilize three-body resonances to so-called bound states in a continuum: resonances with vanishing width that do not decay. Within a two-channel approach we unveil the underlying mechanism and show how the lifetime can be made infinitely long by a continuous tuning of system parameters. The validity of our theory is illustrated in two different examples: a mass-imbalanced system in one dimension and a system of three identical bosons in three dimensions, relevant to Efimov physics. Crucially, for the latter we find that one of the parameters that can be tuned to achieve a three-body bound state in a continuum is an external magnetic field, a common tunable variable in cold-atom experiments. Due to the generality of this stabilization effect, it is expected to be applicable to a wide range of unstable few-body systems, opening new perspectives for fundamental studies as well as technical applications.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript proposes a two-channel theoretical framework for stabilizing three-body resonances into bound states in the continuum (BICs) with exactly vanishing width. Within this reduction, continuous tuning of system parameters is shown to drive the resonance lifetime to infinity. The approach is illustrated with two examples: a mass-imbalanced three-body system in one dimension and three identical bosons in three dimensions (Efimov case), where an external magnetic field serves as one tunable parameter.
Significance. If the two-channel mechanism is robust, the work identifies a general route to creating long-lived three-body states from resonances, with immediate experimental relevance in cold-atom settings via magnetic-field tuning. The claim of applicability to a wide range of few-body systems would be strengthened by explicit checks against neglected channels.
major comments (1)
- [Two-channel framework and examples] The central claim that the resonance width can be tuned exactly to zero (and the lifetime made infinite) is derived within a two-channel model. The manuscript does not provide bounds, comparisons, or explicit multi-channel calculations demonstrating that omitted channels or higher-order corrections do not introduce a residual, untunable width. This directly affects the load-bearing assertion that the stabilization survives in realistic systems (see abstract and the two example sections).
minor comments (1)
- Notation for the two-channel coupling and the definition of the tunable parameters should be made fully explicit in the main text to allow independent reproduction of the zero-width condition.
Simulated Author's Rebuttal
We thank the referee for the careful reading of our manuscript and the constructive feedback. We address the major comment below.
read point-by-point responses
-
Referee: [Two-channel framework and examples] The central claim that the resonance width can be tuned exactly to zero (and the lifetime made infinite) is derived within a two-channel model. The manuscript does not provide bounds, comparisons, or explicit multi-channel calculations demonstrating that omitted channels or higher-order corrections do not introduce a residual, untunable width. This directly affects the load-bearing assertion that the stabilization survives in realistic systems (see abstract and the two example sections).
Authors: Our central result is the identification of a tunable mechanism that drives the three-body resonance width exactly to zero inside a two-channel reduction; this is shown analytically and numerically for the two concrete examples. The two-channel framework is the minimal setting in which the stabilization occurs via continuous parameter tuning, and both examples are drawn from regimes where this reduction is standard and well justified in the literature. We acknowledge that the manuscript does not contain explicit multi-channel calculations or quantitative bounds on possible residual widths from omitted channels. The abstract statement that the effect is expected to apply more broadly is therefore an extrapolation based on the generality of the interference mechanism rather than a claim of proven robustness in full multi-channel systems. We are prepared to revise the manuscript to clarify the scope of the claim, to add a dedicated paragraph justifying the two-channel approximation for each example, and to discuss qualitatively the conditions under which additional channels would or would not lift the exact zero-width condition. revision: partial
- Explicit multi-channel calculations or quantitative bounds on residual widths arising from channels omitted in the two-channel reduction
Circularity Check
No significant circularity; derivation remains self-contained within stated model
full rationale
The paper advances a two-channel framework to demonstrate stabilization of three-body resonances to bound states in the continuum via continuous parameter tuning, illustrated with 1D mass-imbalanced and 3D Efimov examples. No quoted equations or steps reduce the zero-width condition to a fitted parameter by construction, nor does any load-bearing premise collapse to a self-citation chain or renamed ansatz. The central claim is presented as a consequence of the two-channel reduction itself, with the model's assumptions stated explicitly rather than smuggled in; external benchmarks or multi-channel extensions are not required for the internal derivation to hold as formulated.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption A two-channel description is sufficient to capture the resonance lifetime and its tuning to zero width.
Reference graph
Works this paper leans on
-
[1]
(9) whereris the distance between the interacting particles. This three-body problem is then solved in two ways: (i) directly solving the three-body Schr¨ odinger equation us- ing the Gaussian expansion method [59, 60] with complex scaling [9], and (ii) employing the Born-Oppenheimer ap- proximation (see Methods) in which the two deepest po- tential curve...
-
[2]
Accordingly, prel = ℏ z0 q (1 +β) E(3) −E (2) /B2 is given in units ofℏ/z 0, and the momentum is scanned by varying the mass ratio in the range 1/20≤β≤20. Upper panel: The three-body reso- nance (solid red line) is located in the atom-dimer continuum induced by the two-body ground state at energyE (2) g (dashed black line). The resonance width (shaded are...
-
[3]
Hoyle, On Nuclear Reactions Occuring in Very Hot STARS.I
F. Hoyle, On Nuclear Reactions Occuring in Very Hot STARS.I. the Synthesis of Elements from Carbon to Nickel., The Astrophysical Journal Supplement Series1, 121 (1954)
work page 1954
-
[4]
Hyodo, Structure and compositeness of hadron reso- nances, Int
T. Hyodo, Structure and compositeness of hadron reso- nances, Int. J. Mod. Phys. A28, 1330045 (2013)
work page 2013
-
[5]
F.-K. Guo, C. Hanhart, U.-G. Meißner, Q. Wang, Q. Zhao, and B.-S. Zou, Hadronic molecules, Rev. Mod. Phys.90, 015004 (2018)
work page 2018
-
[6]
T. Kraemer, M. Mark, P. Waldburger, J. G. Danzl, C. Chin, B. Engeser, A. D. Lange, K. Pilch, A. Jaakkola, H.-C. N¨ agerl, and R. Grimm, Evidence for Efimov quan- tum states in an ultracold gas of caesium atoms, Nature 440, 315 (2006)
work page 2006
- [7]
-
[8]
T. Kazimierczuk, D. Fr¨ ohlich, S. Scheel, H. Stolz, and M. Bayer, Giant Rydberg excitons in the copper oxide Cu2O, Nature514, 343 (2014)
work page 2014
-
[9]
P. A. Belov, F. Morawetz, S. O. Kr¨ uger, N. Scheuler, P. Rommel, J. Main, H. Giessen, and S. Scheel, Energy states of Rydberg excitons in finite crystals: From weak to strong confinement, Phys. Rev. B109, 235404 (2024)
work page 2024
-
[10]
V. I. Kukulin, V. M. Krasnopol’sky, and J. Hor´ aˇ cek, Theory of Resonances(Springer Netherlands, Dordrecht, 1989)
work page 1989
-
[11]
N. Moiseyev, Quantum theory of resonances: calculating energies, widths and cross-sections by complex scaling, Physics Reports302, 212 (1998)
work page 1998
-
[12]
V. Efimov, Energy levels arising from resonant two-body forces in a three-body system, Physics Letters B33, 563 (1970)
work page 1970
-
[13]
Efimov, Energy levels of three resonantly interacting particles, Nuclear Physics A210, 157 (1973)
V. Efimov, Energy levels of three resonantly interacting particles, Nuclear Physics A210, 157 (1973)
work page 1973
-
[14]
P. Naidon and S. Endo, Efimov physics: a review, Rep. Prog. Phys.80, 056001 (2017)
work page 2017
-
[15]
B. D. Esry, C. H. Greene, and J. P. Burke, Recombination of Three Atoms in the Ultracold Limit, Phys. Rev. Lett. 83, 1751 (1999)
work page 1999
-
[16]
J. P. D’Incao, H. Suno, and B. D. Esry, Limits on Uni- versality in Ultracold Three-Boson Recombination, Phys. Rev. Lett.93, 123201 (2004)
work page 2004
-
[17]
F. M. Pen’kov, Lifetime of Efimov states of negative two- atom ions, Phys. Rev. A60, 3756 (1999)
work page 1999
-
[18]
E. Nielsen, H. Suno, and B. D. Esry, Efimov resonances in atom-diatom scattering, Phys. Rev. A66, 012705 (2002)
work page 2002
-
[19]
Pricoupenko, Crossover in the Efimov spectrum, Phys
L. Pricoupenko, Crossover in the Efimov spectrum, Phys. Rev. A82, 043633 (2010)
work page 2010
-
[20]
L. Happ, P. Naidon, and E. Hiyama, Mass Ratio Depen- dence of Three-Body Resonance Lifetimes in 1D and 3D, Few-Body Syst65, 38 (2024)
work page 2024
- [21]
-
[22]
A. Y. Chuang, H. Q. Bui, A. Christianen, Y. Zhang, Y. Ni, D. Ahmed-Braun, C. Robens, and M. Zwierlein, Observation of a Halo Trimer in an Ultracold Bose-Fermi Mixture, Phys. Rev. X15, 021098 (2025)
work page 2025
- [23]
- [24]
-
[25]
X.-Y. Wang, M. D. Frye, Z. Su, J. Cao, L. Liu, D.-C. Zhang, H. Yang, J. M. Hutson, B. Zhao, C.-L. Bai, and J.-W. Pan, Magnetic Feshbach resonances in collisions of 23Na 40K with 40K, New J. Phys.23, 115010 (2021)
work page 2021
-
[26]
M. A. Nichols, Y.-X. Liu, L. Zhu, M.-G. Hu, Y. Liu, and K.-K. Ni, Detection of Long-Lived Complexes in Ultra- cold Atom-Molecule Collisions, Phys. Rev. X12, 011049 (2022)
work page 2022
-
[27]
H. Son, J. J. Park, Y.-K. Lu, A. O. Jamison, T. Kar- man, and W. Ketterle, Control of reactive collisions by quantum interference, Science375, 1006 (2022)
work page 2022
- [28]
-
[29]
J. J. Park, H. Son, Y.-K. Lu, T. Karman, M. Gronowski, M. Tomza, A. O. Jamison, and W. Ketterle, Spectrum of Feshbach Resonances in NaLi + Na Collisions, Phys. Rev. X13, 031018 (2023)
work page 2023
- [30]
-
[31]
C. W. Hsu, B. Zhen, A. D. Stone, J. D. Joannopoulos, and M. Soljaˇ ci´ c, Bound states in the continuum, Nat Rev Mater1, 1 (2016)
work page 2016
-
[32]
J. von Neumann and E. Wigner, ¨Uber merkw¨ urdige diskrete Eigenwerte, Phys. Z.30, 465 (1929)
work page 1929
-
[33]
F. H. Stillinger and D. R. Herrick, Bound states in the continuum, Phys. Rev. A11, 446 (1975)
work page 1975
-
[34]
H. Friedrich and D. Wintgen, Interfering resonances and bound states in the continuum, Phys. Rev. A32, 3231 (1985)
work page 1985
-
[35]
D. C. Marinica, A. G. Borisov, and S. V. Shabanov, Bound States in the Continuum in Photonics, Phys. Rev. Lett.100, 183902 (2008)
work page 2008
-
[36]
P. S. Pankin, B.-R. Wu, J.-H. Yang, K.-P. Chen, I. V. Timofeev, and A. F. Sadreev, One-dimensional photonic bound states in the continuum, Commun Phys3, 91 (2020)
work page 2020
- [37]
-
[38]
M. Chilcott, S. Gayen, J. Croft, R. Thomas, and N. Kjær- gaard, Observing S-Matrix Pole Flow in Resonance In- terplay, Few-Body Syst65, 61 (2024)
work page 2024
-
[39]
Feshbach, Unified theory of nuclear reactions, Annals of Physics5, 357 (1958)
H. Feshbach, Unified theory of nuclear reactions, Annals of Physics5, 357 (1958)
work page 1958
-
[40]
Fano, Effects of Configuration Interaction on Intensi- ties and Phase Shifts, Phys
U. Fano, Effects of Configuration Interaction on Intensi- ties and Phase Shifts, Phys. Rev.124, 1866 (1961)
work page 1961
- [41]
-
[42]
C. Chin, R. Grimm, P. Julienne, and E. Tiesinga, Fesh- bach resonances in ultracold gases, Rev. Mod. Phys.82, 1225 (2010)
work page 2010
-
[43]
E. K. Laird, T. Kirk, M. M. Parish, and J. Levinsen, Long-lived trimers in a quasi-two-dimensional Fermi sys- tem, Phys. Rev. A97, 042711 (2018)
work page 2018
-
[44]
Bulgac, Dilute Quantum Droplets, Physical Review Letters89, 050402 (2002)
A. Bulgac, Dilute Quantum Droplets, Physical Review Letters89, 050402 (2002)
work page 2002
-
[45]
E. Braaten, H.-W. Hammer, and M. Kusunoki, Efimov States in a Bose-Einstein Condensate near a Feshbach Resonance, Phys. Rev. Lett.90, 170402 (2003)
work page 2003
-
[46]
S. Musolino, H. Kurkjian, M. Van Regemortel, M. Wouters, S. J. J. M. F. Kokkelmans, and V. E. Co- lussi, Bose-Einstein Condensation of Efimovian Triples in the Unitary Bose Gas, Phys. Rev. Lett.128, 020401 (2022)
work page 2022
-
[47]
S. Piatecki and W. Krauth, Efimov-driven phase transi- tions of the unitary Bose gas, Nature Communications5, 3503 (2014)
work page 2014
-
[48]
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, Science378, 1009 (2022)
work page 2022
-
[49]
S. Endo, E. Epelbaum, P. Naidon, Y. Nishida, K. Sekiguchi, and Y. Takahashi, Three-body forces and Efimov physics in nuclei and atoms, Eur. Phys. J. A61, 9 (2025)
work page 2025
-
[50]
´A. Rapp, G. Zar´ and, C. Honerkamp, and W. Hofstetter, Color Superfluidity and “Baryon” Formation in Ultracold Fermions, Physical Review Letters98, 160405 (2007)
work page 2007
- [51]
-
[52]
M. Born and R. Oppenheimer, Zur Quantentheorie der Molekeln, Ann. Phys.389, 457 (1927)
work page 1927
-
[53]
C. D. Lin, Hyperspherical coordinate approach to atomic and other Coulombic three-body systems, Physics Re- ports257, 1 (1995)
work page 1995
-
[54]
E. Nielsen, D. V. Fedorov, A. S. Jensen, and E. Garrido, The three-body problem with short-range interactions, Physics Reports347, 373 (2001)
work page 2001
-
[55]
Naidon, Closed-channel parameters of Feshbach reso- nances, SciPost Physics18, 036 (2025)
P. Naidon, Closed-channel parameters of Feshbach reso- nances, SciPost Physics18, 036 (2025)
work page 2025
-
[56]
Wentzel, Eine Verallgemeinerung der Quantenbedin- gungen f¨ ur die Zwecke der Wellenmechanik, Z
G. Wentzel, Eine Verallgemeinerung der Quantenbedin- gungen f¨ ur die Zwecke der Wellenmechanik, Z. Physik 38, 518 (1926)
work page 1926
-
[57]
H. A. Kramers, Wellenmechanik und halbzahlige Quan- tisierung, Z. Physik39, 828 (1926)
work page 1926
-
[58]
L. Brillouin, La m´ ecanique ondulatoire de Schr¨ odinger; une m´ ethode g´ en´ erale de r´ esolution par approximations successives, CR Acad. Sci183, 24 (1926)
work page 1926
-
[59]
L. D. Landau and E. M. Lifschitz,Quantum Mechanics (Pergamon, New York, 1958)
work page 1958
-
[60]
)1/(N−1) is employed, or evenµ= 1 when the mass is used to rescale the coordinates
In a Born-Oppenheimer descriptionµwould indicate the heavy-particles reduced mass, whereas in a hyperspher- ical approach often theN-body reduced massµ N = (µ12µ12,3 . . .)1/(N−1) is employed, or evenµ= 1 when the mass is used to rescale the coordinates
- [61]
- [62]
-
[63]
E. Tiesinga, B. J. Verhaar, and H. T. C. Stoof, Thresh- old and resonance phenomena in ultracold ground-state collisions, Phys. Rev. A47, 4114 (1993)
work page 1993
-
[64]
Here,δµ B refers to the differenceδµ B =µ atoms−µmolecule between the respective magnetic momentsµ atoms and µmolecule of separated atoms and the molecular bare bound state. For further details, see Ref. [40]
-
[65]
G. V. Skorniakov and K. A. Ter-Martirosian, Three Body Problem for Short Range Forces. I. Scattering of Low Energy Neutrons by Deuterons, Sov. Phys. JETP4, 648 (1957)
work page 1957
-
[66]
L. H. Thomas, The Interaction Between a Neutron and a Proton and the Structure of H 3, Phys. Rev.47, 903 (1935)
work page 1935
-
[67]
J. Wang, J. P. D’Incao, B. D. Esry, and C. H. Greene, Origin of the Three-Body Parameter Universality in Efi- mov Physics, Phys. Rev. Lett.108, 263001 (2012)
work page 2012
-
[68]
S. Endo, M. Ueda, and P. Naidon, Microscopic Origin and Universality Classes of the Efimov Three-Body Pa- rameter, Phys. Rev. Lett.112, 105301 (2014)
work page 2014
-
[69]
P. K. Sørensen, D. V. Fedorov, and A. S. Jensen, Three- Body Recombination Rates Near a Feshbach Resonance within a Two-Channel Contact Interaction Model, Few- Body Syst54, 579 (2013). 9 ACKNOWLEDGMENTS L. H. is supported by the RIKEN special postdoctoral researcher program. P. N. acknowledges support from the JSPS Grants-in-Aid for Scientific Research on...
work page 2013
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.