- Physical Review Journals
All JournalsPhysics Magazine

PRX Quantum

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
  • Open Access

Enhancing Optical Lattice Clock Coherence Times with Erasure Conversion

Shuo Ma*, Jonathan Dolde*, Xin Zheng*, Dhruva Ganapathy, Alexander Shtov, Jenny Chen, Anke Stöltzel, Bennett J. Christensen, and Shimon Kolkowitz†

  • *S.M., J.D., and X.Z. contributed equally to this work.
  • †Contact author: kolkowitz@berkeley.edu
PDF

PRX Quantum 6, 040340 – Published 19 November, 2025

DOI: https://doi.org/10.1103/2rqf-r9gw

Abstract

Increasing coherent interrogation times is central to advancing the precision of optical clocks. Synchronous differential optical clock comparisons have now demonstrated atomic coherence times that far exceed the coherence time of the clock laser. While atom coherence times are then primarily limited by errors induced by lattice Raman scattering, excited clock state radiative decay, and broadening from two-body collisions, many of these errors take the atoms out of the clock transition subspace, and can therefore be converted into “erasure” errors if the appropriate readout scheme is employed. Here we experimentally demonstrate a hyperfine-resolved readout technique for 87Sr optical lattice clocks that mitigates decoherence from Raman scattering induced by the lattice as well as radiative decay. By employing hyperfine-resolved readout in synchronous differential comparisons between 87Sr ensembles with both Ramsey and spin-echo spectroscopy sequences, we achieve enhanced atomic coherence times exceeding 100 and 150 s, respectively, enabling longer coherent measurements without a reduction in performance. We anticipate that this hyperfine-resolved readout technique will benefit applications of state-of-the-art optical lattice clock comparisons in which the coherence times are constrained by Raman scattering or radiative decay.

View figure in article

Physics Subject Headings (PhySH)

Popular Summary

The rapid development of optical lattice atomic clocks has culminated in precision and accuracy at 19 digits and beyond, opening up new possibilities for using these clocks to test general relativity, detect gravitational waves, and search for physics beyond the standard model. Many of these applications require that the atoms remain coherent for long times. In most optical clocks the coherence time is limited by the noise of the laser used to probe the atoms, but by performing synchronous comparisons between multiple ensembles of atoms it is possible to bypass the laser noise, resulting in long coherence times and ultraprecise measurements of the frequency differences between the ensembles.

In this manuscript we adapt a quantum error detection and correction technique known as erasure conversion, originally proposed for quantum computing, to mitigate decoherence arising from scattering and decay events in synchronous optical clock comparisons between ensembles of strontium-87. This technique allows us to measure the coherent atoms that remain in the clock subspace while identifying and excluding the atoms that have experienced scattering and decay events. In our scheme we exploit the multiplicity of strontium-87’s ground state to perform erasure conversion using a hyperfine-resolved readout technique. We find that by rejecting many of the atoms that have experienced an error the coherence times of the clock comparisons increase by roughly a factor of 2, reaching 100 s for a synchronous Ramsey measurement and over 150 s for a spin-echo measurement.

We show that erasure conversion enables the use of a much wider range of coherent interrogation times with minimal impact on stability. We therefore expect that this technique will be useful in applications such as gravitational wave detection and dark matter searches, where variable coherent interrogation times are desirable to search for signals across a wide range of different frequencies.

Article Text

References (40)

  1. T. Bothwell, C. J. Kennedy, A. Aeppli, D. Kedar, J. M. Robinson, E. Oelker, A. Staron, and J. Ye, Resolving the gravitational redshift across a millimetre-scale atomic sample, Nature 602, 420 (2022).
  2. X. Zheng, J. Dolde, V. Lochab, B. N. Merriman, H. Li, and S. Kolkowitz, Differential clock comparisons with a multiplexed optical lattice clock, Nature 602, 425 (2022).
  3. N. Huntemann, C. Sanner, B. Lipphardt, C. Tamm, and E. Peik, Single-ion atomic clock with 3×10−18 systematic uncertainty, Phys. Rev. Lett. 116, 063001 (2016).
  4. W. F. McGrew, X. Zhang, R. J. Fasano, S. A. Schäffer, K. Beloy, D. Nicolodi, R. C. Brown, N. Hinkley, G. Milani, M. Schioppo, T. H. Yoon, and A. D. Ludlow, Atomic clock performance enabling geodesy below the centimetre level, Nature 564, 87 (2018).
  5. T. Bothwell, D. Kedar, E. Oelker, J. M. Robinson, S. L. Bromley, W. L. Tew, J. Ye, and C. J. Kennedy, JILA SrI optical lattice clock with uncertainty of 2.0×10−18, Metrologia 56, 065004 (2019).
  6. S. M. Brewer, J.-S. Chen, A. M. Hankin, E. R. Clements, C. W. Chou, D. J. Wineland, D. B. Hume, and D. R. Leibrandt, 27Al+ quantum-logic clock with a systematic uncertainty below 10−18, Phys. Rev. Lett. 123, 033201 (2019).
  7. A. Aeppli, K. Kim, W. Warfield, M. S. Safronova, and J. Ye, Clock with 8×10−19 systematic uncertainty, Phys. Rev. Lett. 133, 023401 (2024).
  8. C. W. Chou, D. B. Hume, T. Rosenband, and D. J. Wineland, Optical clocks and relativity, Science 329, 1630 (2010).
  9. T. Takano, M. Takamoto, I. Ushijima, N. Ohmae, T. Akatsuka, A. Yamaguchi, Y. Kuroishi, H. Munekane, B. Miyahara, and H. Katori, Geopotential measurements with synchronously linked optical lattice clocks, Nat. Photonics 10, 662 (2016).
  10. M. Takamoto, I. Ushijima, N. Ohmae, T. Yahagi, K. Kokado, H. Shinkai, and H. Katori, Test of general relativity by a pair of transportable optical lattice clocks, Nat. Photonics 14, 411 (2020).
  11. X. Zheng, J. Dolde, M. C. Cambria, H. M. Lim, and S. Kolkowitz, A lab-based test of the gravitational redshift with a miniature clock network, Nat. Commun. 14, 4886 (2023).
  12. A. Derevianko and M. Pospelov, Hunting for topological dark matter with atomic clocks, Nat. Phys. 10, 933 (2014).
  13. C. J. Kennedy, E. Oelker, J. M. Robinson, T. Bothwell, D. Kedar, W. R. Milner, G. E. Marti, A. Derevianko, and J. Ye, Precision metrology meets cosmology: Improved constraints on ultralight dark matter from atom-cavity frequency comparisons, Phys. Rev. Lett. 125, 201302 (2020).
  14. S. Kolkowitz, I. Pikovski, N. Langellier, M. D. Lukin, R. L. Walsworth, and J. Ye, Gravitational wave detection with optical lattice atomic clocks, Phys. Rev. D 94, 124043 (2016).
  15. M. S. Safronova, D. Budker, D. DeMille, D. F. J. Kimball, A. Derevianko, and C. W. Clark, Search for new physics with atoms and molecules, Rev. Mod. Phys. 90, 025008 (2018).
  16. A. D. Ludlow, M. M. Boyd, J. Ye, E. Peik, and P. O. Schmidt, Optical atomic clocks, Rev. Mod. Phys. 87, 637 (2015).
  17. E. Oelker, R. B. Hutson, C. J. Kennedy, L. Sonderhouse, T. Bothwell, A. Goban, D. Kedar, C. Sanner, J. M. Robinson, G. E. Marti, D. G. Matei, T. Legero, M. Giunta, R. Holzwarth, F. Riehle, U. Sterr, and J. Ye, Demonstration of 4.8×10−17 stability at 1 s for two independent optical clocks, Nat. Photonics 13, 714 (2019).
  18. R. B. Hutson, A. Goban, G. E. Marti, L. Sonderhouse, C. Sanner, and J. Ye, Engineering quantum states of matter for atomic clocks in shallow optical lattices, Phys. Rev. Lett. 123, 123401 (2019).
  19. J. A. Muniz, D. J. Young, J. R. K. Cline, and J. K. Thompson, Cavity-QED measurements of the 87Sr millihertz optical clock transition and determination of its natural linewidth, Phys. Rev. Res. 3, 023152 (2021).
  20. X.-T. Lu, F. Guo, Y.-Y. Liu, J.-J. Xia, G.-D. Zhao, Y.-X. Chen, Y.-B. Wang, B.-Q. Lu, and H. Chang, Determining the lifetime of the 5s5p3P0o metastable state in 87Sr from the electric dipole matrix element, Phys. Rev. Appl. 21, 024042 (2024).
  21. J. Dolde, D. Ganapathy, X. Zheng, S. Ma, K. Beloy, and S. Kolkowitz, Direct measurement of the 3P0 clock state natural lifetime in 87Sr, Phys. Rev. A 112, 023121 (2025).
  22. S. Dörscher, R. Schwarz, A. Al-Masoudi, S. Falke, U. Sterr, and C. Lisdat, Lattice-induced photon scattering in an optical lattice clock, Phys. Rev. A 97, 063419 (2018).
  23. Y. Wu, S. Kolkowitz, S. Puri, and J. D. Thompson, Erasure conversion for fault-tolerant quantum computing in alkaline earth Rydberg atom arrays, Nat. Commun. 13, 4657 (2022).
  24. S. Ma, G. Liu, P. Peng, B. Zhang, S. Jandura, J. Claes, A. P. Burgers, G. Pupillo, S. Puri, and J. D. Thompson, High-fidelity gates and mid-circuit erasure conversion in an atomic qubit, Nature 622, 279 (2023).
  25. P. Scholl, A. L. Shaw, R. B.-S. Tsai, R. Finkelstein, J. Choi, and M. Endres, Erasure conversion in a high-fidelity Rydberg quantum simulator, Nature 622, 273 (2023).
  26. H. Levine, A. Haim, J. S. C. Hung, N. Alidoust, M. Kalaee, L. DeLorenzo, E. A. Wollack, P. Arrangoiz-Arriola, and A. E. A. Khalajhedayati, Demonstrating a long-coherence dual-rail erasure qubit using tunable transmons, Phys. Rev. X 14, 011051 (2024).
  27. P. Niroula, J. Dolde, X. Zheng, J. Bringewatt, A. Ehrenberg, K. C. Cox, J. Thompson, M. J. Gullans, S. Kolkowitz, and A. V. Gorshkov, Quantum sensing with erasure qubits, Phys. Rev. Lett. 133, 080801 (2024).
  28. D. P. O’Brien, P. Meystre, and H. Walther, Subnatural linewidths in atomic spectroscopy, Adv. At. Mol. Phys. 21, 1 (1985).
  29. T. Gefen, A. Rotem, and A. Retzker, Overcoming resolution limits with quantum sensing, Nat. Commun. 10, 4992 (2019).
  30. Y. S. Hassan, T. Kobayashi, T. Bothwell, J. L. Seigel, B. D. Hunt, K. Beloy, K. Gibble, T. Grogan, and A. D. Ludlow, Ratchet loading and multi-ensemble operation in an optical lattice clock, Quantum Sci. Technol. 9, 045023 (2024).
  31. H. Uys, M. J. Biercuk, A. P. VanDevender, C. Ospelkaus, D. Meiser, R. Ozeri, and J. J. Bollinger, Decoherence due to elastic Rayleigh scattering, Phys. Rev. Lett. 105, 200401 (2010).
  32. R. Halìr and J. Flusser, Numerically stable direct least squares fitting of ellipses, in Proc. 6th International Conference in Central Europe on Computer Graphics and Visualization. WSCG (1998), Vol. 98, pp. 125–132.
  33. M. B. Plenio and P. L. Knight, The quantum-jump approach to dissipative dynamics in quantum optics, Rev. Mod. Phys. 70, 101 (1998).
  34. A. W. Young, W. J. Eckner, W. R. Milner, D. Kedar, M. A. Norcia, E. Oelker, N. Schine, J. Ye, and A. M. Kaufman, Half-minute-scale atomic coherence and high relative stability in a tweezer clock, Nature 588, 408 (2020).
  35. G. E. Marti, R. B. Hutson, A. Goban, S. L. Campbell, N. Poli, and J. Ye, Imaging optical frequencies with 100μHz precision and 1.1μm resolution, Phys. Rev. Lett. 120, 103201 (2018).
  36. S. Ma, J. Dolde, X. Zheng, and S. Kolkowitz, Data for “Enhancing optical lattice clock coherence times with erasure conversion”, zenodo, https://doi.org/10.5281/zenodo.17383024
  37. J. K. Stockton, X. Wu, and M. A. Kasevich, Bayesian estimation of differential interferometer phase, Phys. Rev. A 76, 033613 (2007).
  38. R. Journet, F. Faisant, S. Lee, and M. Cheneau, Differential polarizability of the strontium intercombination transition at 1064.7 nm, Phys. Rev. A 110, 032819 (2024).
  39. T. Middelmann, S. Falke, C. Lisdat, and U. Sterr, High accuracy correction of blackbody radiation shift in an optical lattice clock, Phys. Rev. Lett. 109, 263004 (2012).
  40. M. Bishof, M. J. Martin, M. D. Swallows, C. Benko, Y. Lin, G. Quéméner, A. M. Rey, and J. Ye, Inelastic collisions and density-dependent excitation suppression in a 87Sr optical lattice clock, Phys. Rev. A 84, 052716 (2011).

Outline

Information

PRX Quantum 6, 040340– Published 19 November, 2025
  • Received 9 May 2025
  • Revised 26 August 2025
  • Accepted 16 October 2025
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