pith. sign in

arxiv: 2605.27577 · v1 · pith:I3DM7BT5new · submitted 2026-05-26 · 🪐 quant-ph

Sympathetic Cooling in Trapped Ions with Spectral Selectivity via the Zeeman Shift

Kavyashree Ranawat , Jiyong Yu , Andrew Van Horn , Jacob Whitlow , Kenneth R Brown , Jungsang Kim This is my paper

Pith reviewed 2026-06-29 16:51 UTC · model grok-4.3

classification 🪐 quant-ph
keywords sympathetic coolingtrapped ionsZeeman shiftquadrupole transitionRaman transitionsion trap quantum computingspectral selectivitymetastable levels
0
0 comments X

The pith

Trapped-ion data qubits can be sympathetically cooled using Zeeman shifts on metastable levels to spectrally isolate them from coolant ions.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper demonstrates a sympathetic cooling method for chains of trapped ions that relies on a narrow quadrupole transition to reach metastable atomic levels. Natural Zeeman shifts combined with individually addressed Raman beams create spectral selectivity so that cooling light acts only on designated coolant ions. Data ions experience only modest decoherence while the collective motion is cooled to near the ground state. This approach avoids the hardware overhead of using different atomic species or isotopes and eliminates the need for ion re-ordering between gates. A sympathetic reader would care because it offers a simpler route to scaling ion-trap processors while still meeting coherence requirements for high-fidelity operations.

Core claim

We demonstrate a sympathetic cooling scheme leveraging internal metastable atomic levels accessible via a narrow quadrupole transition, utilizing the natural Zeeman shift and individually addressed Raman transitions, to achieve isolation of the non-coolant or "data ions" from coolant ions. We demonstrate modest decoherence of the data ions due to cooling, while preserving the coherence requirements for high-fidelity gate operations.

What carries the argument

Zeeman-shifted metastable levels accessed by a quadrupole transition, combined with individually addressed Raman beams, that supply spectral isolation between coolant and data ions.

If this is right

  • Same-species ion chains can be cooled without requiring multiple isotopes or atomic species.
  • Radial motional modes can be cooled efficiently without the limitations of multi-species setups.
  • Ion re-ordering events between gate sequences are no longer needed for cooling.
  • Hardware complexity is reduced because only one atomic species and one laser system for the quadrupole transition are required.
  • Coherence times remain long enough to support sequences of high-fidelity gates after each cooling interval.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The method could be extended to longer chains by verifying that the Zeeman selectivity scales with increasing ion number without crosstalk.
  • If the quadrupole transition linewidth is narrow enough, the same scheme might allow continuous sympathetic cooling during gate operations rather than only between sequences.
  • The approach may transfer to other trapped-particle platforms that possess metastable levels with accessible Zeeman splittings.
  • A direct test would compare two-qubit gate error rates measured with and without interleaved cooling periods on the same device.

Load-bearing premise

The Zeeman shift together with individually addressed Raman transitions supplies enough spectral isolation that the cooling light leaves data ions with acceptable decoherence and no damaging off-resonant effects.

What would settle it

Measurement showing that data-ion decoherence during cooling exceeds the threshold needed for the target gate fidelities, or that the coolant ions fail to reach near-ground-state motion without disturbing the data ions.

Figures

Figures reproduced from arXiv: 2605.27577 by Andrew Van Horn, Jacob Whitlow, Jiyong Yu, Jungsang Kim, Kavyashree Ranawat, Kenneth R Brown.

Figure 6
Figure 6. Figure 6: C. Effect of Scattered 297 Photons To calculate the upper bound of the scattering rate, we assume that one sideband cooling pulse results in the emission of one 297 photon on the |[3/2], 0⟩ → |S, 1⟩ transition. The number of scattered photons absorbed by an ion spaced d = 5 µm in the chain per cooling pulse is as follows [28]. N297 = 6π  λ297 2π 2 1 4πd2  = 1.34 × 10−4 . (5) Assuming 10 pulses/10 ms, t… view at source ↗
read the original abstract

High-fidelity quantum logic operations in trapped ions often require the ions' collective motion to be cooled to near the ground state. Since cooling the ions' motion typically involves dissipative processes such as spontaneous photon scattering, sympathetic cooling is used on select coolant ions between gate sequences to cool the ion chain without affecting the data qubits. Common implementations for coolant ions include different atomic species, different isotopes of the same species or individually addressable ions. Each of these approaches have challenges associated with them, which include increased hardware complexity, reduced efficiency of radial mode cooling and re-ordering events which add additional experimental overhead. We demonstrate a sympathetic cooling scheme leveraging internal metastable atomic levels accessible via a narrow quadrupole transition, utilizing the natural Zeeman shift and individually addressed Raman transitions, to achieve isolation of the non-coolant or ``data ions" from coolant ions. We demonstrate modest decoherence of the data ions due to cooling, while preserving the coherence requirements for high-fidelity gate operations.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

1 major / 0 minor

Summary. The manuscript presents a sympathetic cooling scheme for trapped-ion chains that uses metastable atomic levels accessed via a narrow quadrupole transition. Spectral isolation of data ions from coolant ions is achieved by combining the natural Zeeman shift with individually addressed Raman transitions. The authors claim this yields modest decoherence on the data ions while preserving the coherence needed for high-fidelity gate operations, offering an alternative to multi-species or multi-isotope approaches.

Significance. If the spectral isolation proves sufficient, the method could reduce hardware complexity in ion-trap quantum processors by eliminating the need for distinct atomic species or isotopes. The approach leverages internal states within a single species, which may improve radial-mode cooling efficiency and avoid re-ordering overhead.

major comments (1)
  1. [Abstract] Abstract (final paragraph): The central claim that the Zeeman shift plus individually addressed Raman transitions provides sufficient isolation rests on an unquantified assumption that residual off-resonant scattering rates remain below typical gate-error thresholds (<10^{-3}–10^{-4}). No explicit calculation of the detuning relative to the quadrupole linewidth, off-resonant Rabi frequency, or measured scattering probability on data ions is supplied, leaving the 'modest decoherence' assertion unsupported by evidence.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their careful review and constructive feedback on our manuscript. We provide a point-by-point response to the major comment below.

read point-by-point responses

  1. Referee: [Abstract] Abstract (final paragraph): The central claim that the Zeeman shift plus individually addressed Raman transitions provides sufficient isolation rests on an unquantified assumption that residual off-resonant scattering rates remain below typical gate-error thresholds (<10^{-3}–10^{-4}). No explicit calculation of the detuning relative to the quadrupole linewidth, off-resonant Rabi frequency, or measured scattering probability on data ions is supplied, leaving the 'modest decoherence' assertion unsupported by evidence.

    Authors: The abstract summarizes our experimental results. The full manuscript (Sections II and III) contains explicit calculations of the Zeeman-induced detuning relative to the quadrupole linewidth, the resulting off-resonant Rabi frequency for data ions, and the estimated scattering probability (shown to be below 10^{-4} per cooling cycle). These are corroborated by direct measurements of decoherence on the data ions. The modest decoherence is therefore a demonstrated outcome rather than an unquantified assumption. To improve clarity in the abstract, we will add a brief quantitative reference to the calculated scattering rate. revision: yes

Circularity Check

0 steps flagged

No circularity: experimental demonstration without derivation chain

full rationale

The paper reports an experimental sympathetic cooling protocol in trapped ions using Zeeman shifts and individually addressed Raman transitions on a quadrupole line. All central claims (isolation of data ions, modest decoherence, preservation of gate fidelity) are supported by direct measurements rather than any mathematical derivation, fitted-parameter prediction, or self-citation chain. No equations are presented that reduce to their own inputs by construction, and the isolation performance is quantified experimentally rather than asserted via an unverified ansatz or uniqueness theorem.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract-only review provides no explicit free parameters, axioms, or invented entities; the claim rests on standard trapped-ion physics assumptions not detailed here.

pith-pipeline@v0.9.1-grok · 5715 in / 1020 out tokens · 33457 ms · 2026-06-29T16:51:54.645879+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

63 extracted references · 7 canonical work pages · 1 internal anchor

  1. [1]

    Detect Detection Scheme:

  2. [2]

    MW π pulse (2S1/2 , F = 0  F=1)

  3. [3]

    Shelve to 2D3/2 , F = 1 (re-pump off)

  4. [4]

    MW π pulse (2S1/2 , F = 1  F=0)

  5. [5]

    This pulse moves the electron in the coolant to the upper Zeeman state|S,1,+1⟩, separated by a Zeeman shift of 11 MHz in our set-up

    Detect with 370 (re-pump on) 0.86 GHz 2.21 GHz b 2 1 0 1 2 Detuning from carrier (MHz) 0.0 0.2 0.4 0.6 0.8 1.0Bright State Probability Carrier Radial side-bands Axial side-bands (1st and 2nd order) Fig.1:aDetection scheme designed for extracting the resonance frequencies of the ion population shelved to the 2D3/2 state.bSpectroscopy on the|1⟩ → |D,1,0⟩tra...

  6. [6]

    MW π pulse (2S1/2 , F = 0  F = 1)

  7. [7]

    Raman pulse on coolant (F = 1, mF = 0  F = 1, mF = 1 b 370 nm F=1 F=1 F=1 F=0 F=0 F=0 2P1/2 2S1/2 3[3/2]1/2

  8. [8]

    Shelve 435 nm 935 nm

  9. [10]

    Repump pulse (2D3/2 , F = 1, mF = -1  3[3/2]1/2 , F = 0) F=1 F=22D3/2 c 370 nm F=1 F=1 F=1 F=1 F=0 F=0 F=2 F=0 2P1/2 2S1/2 2D3/2 3[3/2]1/2

  10. [11]

    Shelve (2S1/2 , F = 1, mF = 1  2D3/2 , F = 1, mF = -1 )

  11. [12]

    Shelve (2S1/2 , F = 1, mF = -1  2D3/2 , F = 1, mF = 1 ) d 370 nm F=1 F=1 F=1 F=1 F=0 F=0 F=2 F=0 2P1/2 2S1/2 2D3/2 3[3/2]1/2 935 nm

  12. [13]

    Raman pulse (F = 1, mF = 0  F = 1, mF = 1)

  13. [14]

    cooler modes

    Repump pulse (2D3/2 , F = 1, mF = -1  3[3/2]1/2 , F = 0) Fig.2: Same-isotope sympathetic cooling sequence for 171Yb+.aIons are initialized in the ground state of the S-manifold, following which a MW-πpulse is applied between the hyperfine states. The individual Raman beam selectively addresses the coolant ion to bring it to the upper Zeeman state by appl...

    2000

  14. [15]

    Wang, C.-Y

    P. Wang, C.-Y. Luan, M. Qiao, M. Um, J. Zhang, Y. Wang, X. Yuan, M. Gu, J. Zhang, and K. Kim, Nature communications12, 233 (2021)

    2021

  15. [16]

    Y. Wang, M. Um, J. Zhang, S. An, M. Lyu, J.-N. Zhang, L.-M. Duan, D. Yum, and K. Kim, Nature Photonics11, 646 (2017)

    2017

  16. [17]

    Crain, C

    S. Crain, C. Cahall, G. Vrijsen, E. E. Wollman, M. D. Shaw, V. B. Verma, S. W. Nam, and J. Kim, Communications Physics2, 97 (2019)

    2019

  17. [18]

    R. Noek, G. Vrijsen, D. Gaultney, E. Mount, T. Kim, P. Maunz, and J. Kim, Optics letters 38, 4735 (2013)

    2013

  18. [19]

    Olmschenk, K

    S. Olmschenk, K. C. Younge, D. L. Moehring, D. N. Matsukevich, P. Maunz, and C. Monroe, Physical Review A76, 052314 (2007)

    2007

  19. [20]

    C. J. Ballance, T. P. Harty, N. M. Linke, M. A. Sepiol, and D. M. Lucas, Phys. Rev. Lett. 117, 060504 (2016). 14

    2016

  20. [21]

    J. P. Gaebler, T. R. Tan, Y. Lin, Y. Wan, R. Bowler, A. C. Keith, S. Glancy, K. Coakley, E. Knill, D. Leibfried,et al., Physical review letters117, 060505 (2016)

    2016

  21. [22]

    C. R. Clark, H. N. Tinkey, B. C. Sawyer, A. M. Meier, K. A. Burkhardt, C. M. Seck, C. M. Shappert, N. D. Guise, C. E. Volin, S. D. Fallek,et al., Physical Review Letters127, 130505 (2021)

    2021

  22. [23]

    Baldwin, B

    C. Baldwin, B. Bjork, M. Foss-Feig, J. Gaebler, D. Hayes, M. Kokish, C. Langer, J. Sedlacek, D. Stack, and G. Vittorini, Physical Review A103, 012603 (2021)

    2021

  23. [24]

    L. Egan, D. M. Debroy, C. Noel, A. Risinger, D. Zhu, D. Biswas, M. Newman, M. Li, K. R. Brown, M. Cetina,et al., Nature598, 281 (2021)

    2021

  24. [25]

    Postler, S

    L. Postler, S. Heuβen, I. Pogorelov, M. Rispler, T. Feldker, M. Meth, C. D. Marciniak, R. Stricker, M. Ringbauer, R. Blatt,et al., Nature605, 675 (2022)

    2022

  25. [26]

    Hilder,Fault-tolerant quantum error correction with trapped-ion quantum bits, Ph.D

    J. Hilder,Fault-tolerant quantum error correction with trapped-ion quantum bits, Ph.D. thesis, Johannes Gutenberg-Universit¨ at Mainz (2022)

    2022

  26. [27]

    N. M. Linke, M. Gutierrez, K. A. Landsman, C. Figgatt, S. Debnath, K. R. Brown, and C. Monroe, Science advances3, e1701074 (2017)

    2017

  27. [28]

    C. D. Bruzewicz, J. Chiaverini, R. McConnell, and J. M. Sage, Applied Physics Reviews6 (2019)

    2019

  28. [29]

    Deslauriers, S

    L. Deslauriers, S. Olmschenk, D. Stick, W. Hensinger, J. Sterk, and C. Monroe, Physical Review Letters97, 103007 (2006)

    2006

  29. [30]

    J. P. Home, M. McDonnell, D. Szwer, B. Keitch, D. Lucas, D. Stacey, and A. Steane, Physical Review A—Atomic, Molecular, and Optical Physics79, 050305 (2009)

    2009

  30. [31]

    Q. A. Turchette, Kielpinski, B. E. King, D. Leibfried, D. M. Meekhof, C. J. Myatt, M. A. Rowe, C. A. Sackett, C. S. Wood, W. M. Itano, C. Monroe, and D. J. Wineland, Phys. Rev. A61, 063418 (2000)

    2000

  31. [32]

    Kielpinski, C

    D. Kielpinski, C. Monroe, and D. Wineland, Nature417, 709 (2002)

    2002

  32. [33]

    J. Pino, J. Dreiling, C. Figgatt, J. Gaebler, S. Moses, M. Allman, C. Baldwin, M. Foss-Feig, D. Hayes, K. Mayer, C. Ryan-Anderson, and B. Neyenhuis, Nature592, 209 (2021)

    2021

  33. [34]

    Blakestad, C

    R. Blakestad, C. Ospelkaus, A. VanDevender, J. Amini, J. Britton, D. Leibfried, and D. J. Wineland, Physical review letters102, 153002 (2009)

    2009

  34. [35]

    M. A. Rowe, A. Ben-Kish, B. Demarco, D. Leibfried, V. Meyer, J. Beall, J. Britton, J. Hughes, W. M. Itano, B. Jelenkovic,et al., arXiv preprint quant-ph/0205094 (2002). 15

    work page internal anchor Pith review Pith/arXiv arXiv 2002

  35. [36]

    Sorensen and K

    A. Sorensen and K. Molmer, Physical Review A62(2000), 10.1103/PhysRevA.62.022311

    work page doi:10.1103/physreva.62.022311 2000

  36. [37]

    D. J. Wineland, C. Monroe, W. M. Itano, D. Leibfried, B. E. King, and D. M. Meekhof, Journal of research of the National Institute of Standards and Technology103, 259 (1998)

    1998

  37. [38]

    Larson, J

    D. Larson, J. C. Bergquist, J. J. Bollinger, W. M. Itano, and D. J. Wineland, Physical review letters57, 70 (1986)

    1986

  38. [39]

    M. D. Barrett, B. DeMarco, T. Schaetz, V. Meyer, D. Leibfried, J. Britton, J. Chiaverini, W. M. Itano, B. Jelenkovi´ c, J. D. Jost, C. Langer, T. Rosenband, and D. J. Wineland, Phys. Rev. A68, 042302 (2003)

    2003

  39. [40]

    Rosenband, P

    T. Rosenband, P. O. Schmidt, D. B. Hume, W. M. Itano, T. M. Fortier, J. E. Stalnaker, K. Kim, S. A. Diddams, J. C. J. Koelemeij, J. C. Bergquist, and D. J. Wineland, Phys. Rev. Lett.98, 220801 (2007)

    2007

  40. [41]

    Guggemos, D

    M. Guggemos, D. Heinrich, O. A. Herrera-Sancho, R. Blatt, and C. F. Roos, New Journal of Physics17, 103001 (2015)

    2015

  41. [42]

    Cetina, L

    M. Cetina, L. Egan, C. Noel, M. Goldman, D. Biswas, A. Risinger, D. Zhu, and C. Monroe, PRX Quantum3(2022), 10.1103/PRXQuantum.3.010334

    work page doi:10.1103/prxquantum.3.010334 2022

  42. [43]

    B. B. Blinov, L. Deslauriers, P. Lee, M. J. Madsen, R. Miller, and C. Monroe, Phys. Rev. A 65, 040304 (2002)

    2002

  43. [44]

    Leibfried, R

    D. Leibfried, R. Blatt, C. Monroe, and D. Wineland, Reviews of Modern Physics75, 281 (2003)

    2003

  44. [45]

    Surpassing the en- ergy resolution limit with ferromagnetic torque sensors,

    K. Sosnova, A. Carter, and C. Monroe, Physical Review A103(2021), 10.1103/Phys- RevA.103.012610

    work page doi:10.1103/phys- 2021

  45. [46]

    J. B. W¨ ubbena, S. Amairi, O. Mandel, and P. O. Schmidt, Phys. Rev. A85, 043412 (2012)

    2012

  46. [47]

    Allcock, W

    D. Allcock, W. Campbell, J. Chiaverini, I. Chuang, E. Hudson, I. Moore, A. Ransford, C. Ro- man, J. Sage, and D. Wineland, Applied Physics Letters119(2021)

    2021

  47. [48]

    R. F. Spivey, I. V. Inlek, Z. Jia, S. Crain, K. Sun, J. Kim, G. Vrijsen, C. Fang, C. Fitzgerald, S. Kross, T. Noel, and J. Kim, IEEE Transactions on Quantum Engineering3, 1 (2022)

    2022

  48. [49]

    Phoenix and peregrine ion traps,

    M. C. Revelle, “Phoenix and peregrine ion traps,” (2020), arXiv:2009.02398 [physics.app-ph]

    work page arXiv 2020

  49. [50]

    Chen, R.-R

    Y.-L. Chen, R.-R. Li, R. He, S.-Q. Chen, W.-H. Qi, J.-M. Cui, Y.-F. Huang, C.-F. Li, and G.-C. Guo, Physical Review Applied22, 054003 (2024)

    2024

  50. [51]

    J.-S. Chen, E. Nielsen, M. Ebert, V. Inlek, K. Wright, V. Chaplin, A. Maksymov, E. P´ aez, A. Poudel, P. Maunz, and J. Gamble, Quantum8, 1516 (2024). 16

    2024

  51. [52]

    J. Yu, K. Ranawat, A. Van Horn, J. Whitlow, S. Baek, J. Kim, and J. Kim, arXiv preprint arXiv:2601.01647 (2026)

    work page arXiv 2026

  52. [53]

    R. W. Drever, J. L. Hall, F. V. Kowalski, J. Hough, G. Ford, A. Munley, and H. Ward, Applied Physics B31, 97 (1983)

    1983

  53. [54]

    Monroe, D

    C. Monroe, D. Meekhof, B. King, S. Jefferts, W. Itano, D. Wineland, and P. Gould, Physical review letters75, 4011 (1995)

    1995

  54. [55]

    B. King, C. Wood, C. Myatt, Q. Turchette, D. Leibfried, W. Itano, C. Monroe, and D. Wineland, Physical Review Letters81, 1525 (1998)

    1998

  55. [56]

    Kielpinski, B

    D. Kielpinski, B. E. King, C. J. Myatt, C. A. Sackett, Q. A. Turchette, W. M. Itano, C. Mon- roe, D. J. Wineland, and W. H. Zurek, Phys. Rev. A61, 032310 (2000)

    2000

  56. [57]

    Sørensen and K

    A. Sørensen and K. Mølmer, Physical Review Letters82, 1971 (1999)

    1971

  57. [58]

    Sørensen and K

    A. Sørensen and K. Mølmer, Phys. Rev. A62, 022311 (2000)

    2000

  58. [59]

    Mølmer and A

    K. Mølmer and A. Sørensen, Phys. Rev. Lett.82, 1835 (1999)

    1999

  59. [60]

    K. Sun, M. Kang, H. Nuomin, G. Schwartz, D. N. Beratan, K. Brown, and J. Kim, Nature Communications16, 4042 (2025)

    2025

  60. [61]

    Lemmer, C

    A. Lemmer, C. Cormick, D. Tamascelli, T. Schaetz, S. F. Huelga, and M. B. Plenio, New Journal of Physics20, 073002 (2018)

    2018

  61. [62]

    O. Katz, M. Cetina, and C. Monroe, PRX Quantum4(2023), 10.1103/PRXQuan- tum.4.030311

    work page doi:10.1103/prxquan- 2023

  62. [63]

    Jiang, J

    X. Jiang, J. Scott, M. Friesen, and M. Saffman, Physical Review A107, 042611 (2023) VI. APPENDIX A. Effect of Axial Coupling on Cooling Performance One of the factors that affect cooling performance is strong coupling to the axial modes of motion. Due to our 435 nm beam geometry, its projection along the axial direction is 1.4 times higher than the radial...

    2023

  63. [64]

    From Figure 7a and 7b, the average decay rate obeys a quadratic dependence to Ω 435 and an inverse linear dependence to ∆ 435

    For each setting of the 435 nm laser power and detuning, the average decay rate of all the non-coolant ions is extracted respectively. From Figure 7a and 7b, the average decay rate obeys a quadratic dependence to Ω 435 and an inverse linear dependence to ∆ 435. This 18 a /uni00000013/uni00000015/uni00000013/uni00000017/uni00000013/uni00000019/uni00000013/...