- Physical Review Journals
All JournalsPhysics Magazine

Physical Review Research

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

Evaporative cooling by pulse width modulation (PWM) of optical dipole traps

S. Sagar Maurya1,*,†, Joel M. Sunil1, Monu Bhartiya1, Pranab Dutta1, Jay Mangaonkar1, Rahul Sawant2,‡, and Umakant D. Rapol1,§

  • *Contact author: shivsagar.maurya@students.iiserpune.ac.in
  • †Present Address: Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, Braunschweig 38116, Germany.
  • ‡Present Address: Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India.
  • §Contact author: umakant.rapol@iiserpune.ac.in
PDF

Phys. Rev. Research 7, 043050 – Published 15 October, 2025

DOI: https://doi.org/10.1103/fbx6-8l7n

Abstract

We introduce a method for cooling atoms in an optical dipole trap using pulse-width modulation (PWM) technique, without reducing the laser power of the dipole trap. The PWM technique involves digital modulation of the trap at a fixed frequency. The effective time-averaged dipole potential is lowered by adjusting the duty cycle of the modulation, thereby implementing evaporative cooling. We show that this technique effectively reduces temperature and enhances phase space density. A comparison with the standard method of evaporative cooling has also been made. Apart from the atom loss due to reduction of the effective trapping potential, we observe an additional loss channel originating from the lack of trapping potential during the trap “off” time. This atom loss is observed at different modulation frequencies which are an order of magnitude higher compared to trapping frequency of dipole trap. The PWM technique provides an alternative to traditional evaporative cooling in scenarios where it is preferred that the laser power of the trap should be constant.

View figure in article

Physics Subject Headings (PhySH)

Article Text

References (48)

  1. P. Dutta, S. S. Maurya, K. Patel, K. Biswas, J. Mangaonkar, S. Sarkar, and U. D. Rapol, A decade of advancement of quantum sensing and metrology in India using cold atoms and ions, J. Indian Inst. Sci. 103, 609 (2023).
  2. A. D. Cronin, J. Schmiedmayer, and D. E. Pritchard, Optics and interferometry with atoms and molecules, Rev. Mod. Phys. 81, 1051 (2009).
  3. K. S. Hardman, P. J. Everitt, G. D. McDonald, P. Manju, P. B. Wigley, M. A. Sooriyabandara, C. C. N. Kuhn, J. E. Debs, J. D. Close, and N. P. Robins, Simultaneous precision gravimetry and magnetic gradiometry with a Bose-Einstein condensate: A high precision, quantum sensor, Phys. Rev. Lett. 117, 138501 (2016).
  4. S. B. Koller, J. Grotti, S. Vogt, A. Al-Masoudi, S. Dörscher, S. Häfner, U. Sterr, and C. Lisdat, Transportable optical lattice clock with 7×10−17 uncertainty, Phys. Rev. Lett. 118, 073601 (2017).
  5. F.-X. Esnault, E. Blanshan, E. N. Ivanov, R. E. Scholten, J. Kitching, and E. A. Donley, Cold-atom double-Λ coherent population trapping clock, Phys. Rev. A 88, 042120 (2013).
  6. 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 (London) 602, 420 (2022).
  7. M. T. Bell and T. P. Softley, Ultracold molecules and ultracold chemistry, Mol. Phys. 107, 99 (2009).
  8. I. Bloch, J. Dalibard, and W. Zwerger, Many-body physics with ultracold gases, Rev. Mod. Phys. 80, 885 (2008).
  9. I. Bloch, J. Dalibard, and S. Nascimbène, Quantum simulations with ultracold quantum gases, Nat. Phys. 8, 267 (2012).
  10. J. J. García-Ripoll, P. Zoller, and J. I. Cirac, Quantum information processing with cold atoms and trapped ions, J. Phys. B 38, S567 (2005).
  11. E. L. Raab, M. Prentiss, A. Cable, S. Chu, and D. E. Pritchard, Trapping of neutral sodium atoms with radiation pressure, Phys. Rev. Lett. 59, 2631 (1987).
  12. J. Dalibard and C. Cohen-Tannoudji, Laser cooling below the doppler limit by polarization gradients: simple theoretical models, J. Opt. Soc. Am. B 6, 2023 (1989).
  13. M. Kasevich and S. Chu, Laser cooling below a photon recoil with three-level atoms, Phys. Rev. Lett. 69, 1741 (1992).
  14. T. Esslinger, F. Sander, M. Weidemüller, A. Hemmerich, and T. W. Hänsch, Subrecoil laser cooling with adiabatic transfer, Phys. Rev. Lett. 76, 2432 (1996).
  15. R. Grimm, M. Weidemüller, and Y. B. Ovchinnikov, Optical dipole traps for neutral atoms, Adv. At. Mol. Opt. Phys. 42, 95 (2000).
  16. D. Savoie, M. Altorio, B. Fang, L. A. Sidorenkov, R. Geiger, and A. Landragin, Interleaved atom interferometry for high-sensitivity inertial measurements, Sci. Adv. 4, eaau7948 (2018).
  17. J. Chabé, G. Lemarié, B. Grémaud, D. Delande, P. Szriftgiser, and J. C. Garreau, Experimental observation of the Anderson metal-insulator transition with atomic matter waves, Phys. Rev. Lett. 101, 255702 (2008).
  18. S. S. Maurya, J. B. Kannan, K. Patel, P. Dutta, K. Biswas, J. Mangaonkar, M. S. Santhanam, and U. D. Rapol, Interplay between quantum diffusion and localization in the atom-optics kicked rotor, Phys. Rev. E 106, 034207 (2022).
  19. M. D. Barrett, J. A. Sauer, and M. S. Chapman, All-optical formation of an atomic Bose-Einstein condensate, Phys. Rev. Lett. 87, 010404 (2001).
  20. S. Chaudhuri, S. Roy, and C. S. Unnikrishnan, Evaporative cooling of atoms to quantum degeneracy in an optical dipole trap, J. Phys.: Conf. Ser. 80, 012036 (2007).
  21. W. Ketterle and N. van Druten, Evaporative cooling of trapped atoms, Adv. At. Mol. Opt. Phys. 37, 181 (1996).
  22. A. J. Olson, R. J. Niffenegger, and Y. P. Chen, Optimizing the efficiency of evaporative cooling in optical dipole traps, Phys. Rev. A 87, 053613 (2013).
  23. Y.-J. Lin, A. R. Perry, R. L. Compton, I. B. Spielman, and J. V. Porto, Rapid production of Rb87 Bose-Einstein condensates in a combined magnetic and optical potential, Phys. Rev. A 79, 063631 (2009).
  24. S. Kumar, S. Hirai, Y. Suzuki, M. Kachi, M. Sadgrove, and K. Nakagawa, Simple and fast production of Bose–Einstein condensate in a 1µm cross-beam dipole trap, J. Phys. Soc. Jpn. 81, 084004 (2012).
  25. J. Mangaonkar, C. Vishwakarma, S. S. Maurya, S. Sarkar, J. L. MacLennan, P. Dutta, and U. D. Rapol, Effects of finite momentum width on the reversal dynamics in a BEC based atom optics δ-kicked rotor, J. Phys. B: At. Mol. Opt. Phys. 53, 235502 (2020).
  26. D. Jacob, E. Mimoun, L. D. Sarlo, M. Weitz, J. Dalibard, and F. Gerbier, Production of sodium Bose–Einstein condensates in an optical dimple trap, New J. Phys. 13, 065022 (2011).
  27. M. C. Garrett, A. Ratnapala, E. D. van Ooijen, C. J. Vale, K. Weegink, S. K. Schnelle, O. Vainio, N. R. Heckenberg, H. Rubinsztein-Dunlop, and M. J. Davis, Growth dynamics of a Bose-Einstein condensate in a dimple trap without cooling, Phys. Rev. A 83, 013630 (2011).
  28. Y. Wang, Y. Li, J. Wu, W. Liu, J. Hu, J. Ma, L. Xiao, and S. Jia, Hybrid evaporative cooling of Cs133 atoms to Bose-Einstein condensation, Opt. Express 29, 13960 (2021).
  29. J.-F. Clément, J.-P. Brantut, M. Robert-de Saint-Vincent, R. A. Nyman, A. Aspect, T. Bourdel, and P. Bouyer, All-optical runaway evaporation to Bose-Einstein condensation, Phys. Rev. A 79, 061406 (2009).
  30. C.-L. Hung, X. Zhang, N. Gemelke, and C. Chin, Accelerating evaporative cooling of atoms into Bose-Einstein condensation in optical traps, Phys. Rev. A 78, 011604 (2008).
  31. R. Bourgain, J. Pellegrino, A. Fuhrmanek, Y. R. P. Sortais, and A. Browaeys, Evaporative cooling of a small number of atoms in a single-beam microscopic dipole trap, Phys. Rev. A 88, 023428 (2013).
  32. A. Urvoy, Z. Vendeiro, J. Ramette, A. Adiyatullin, and V. Vuletić, Direct laser cooling to Bose-Einstein condensation in a dipole trap, Phys. Rev. Lett. 122, 203202 (2019).
  33. H. Albers, R. Corgier, A. Herbst, A. Rajagopalan, C. Schubert, C. Vogt, M. Woltmann, C. Lämmerzahl, S. Herrmann, E. Charron, W. Ertmer, E. M. Rasel, N. Gaaloul, and D. Schlippert, All-optical matter-wave lens using time-averaged potentials, Commun. Phys. 5, 60 (2022).
  34. T. Kinoshita, T. Wenger, and D. S. Weiss, All-optical Bose-Einstein condensation using a compressible crossed dipole trap, Phys. Rev. A 71, 011602 (2005).
  35. M. Shiddiq, E. M. Ahmed, M. D. Havey, and C. I. Sukenik, Investigation of loading of pulsed and continuous-wave optical dipole force traps, Phys. Rev. A 77, 045401 (2008).
  36. D. N. Yanyshev, V. I. Balykin, Y. V. Vladimirova, and V. N. Zadkov, Dynamics of atoms in a femtosecond optical dipole trap, Phys. Rev. A 87, 033411 (2013).
  37. E. A. Shapiro, V. Milner, C. Menzel-Jones, and M. Shapiro, Piecewise adiabatic passage with a series of femtosecond pulses, Phys. Rev. Lett. 99, 033002 (2007).
  38. M. Harutyunyan, F. Holweck, D. Sugny, and S. Guérin, Digital optimal robust control, Phys. Rev. Lett. 131, 200801 (2023).
  39. H. Xu, X.-K. Song, D. Wang, and L. Ye, Robust coherent control in three-level quantum systems using composite pulses, Opt. Express 30, 3125 (2022).
  40. Y. Sun, Construction of a time-averaged crossed optical dipole trap for ultracold Li6 atoms, Bachelor thesis, Ludwig-Maximilians-Universität München, 2022.
  41. I. Lesanovsky and W. von Klitzing, Time-averaged adiabatic potentials: Versatile matter-wave guides and atom traps, Phys. Rev. Lett. 99, 083001 (2007).
  42. S. S. Maurya, J. B. Kannan, K. Patel, P. Dutta, K. Biswas, M. S. Santhanam, and U. D. Rapol, Asymmetric dynamical localization and precision measurement of the micromotion of a Bose-Einstein condensate, Phys. Rev. A 110, 053307 (2024).
  43. K. Biswas, K. Patel, S. S. Maurya, P. Dutta, and U. D. Rapol, Machine-learning-based automated loading of strontium isotopes into magneto-optical trap, AIP Adv. 13, 075313 (2023).
  44. P. B. Wigley, P. J. Everitt, A. van den Hengel, J. W. Bastian, M. A. Sooriyabandara, G. D. McDonald, K. S. Hardman, C. D. Quinlivan, P. Manju, C. C. N. Kuhn, I. R. Petersen, A. N. Luiten, J. J. Hope, N. P. Robins, and M. R. Hush, Fast machine-learning online optimization of ultra-cold-atom experiments, Sci. Rep. 6, 25890 (2016).
  45. R. Hobson, W. Bowden, A. Vianello, I. R. Hill, and P. Gill, Midinfrared magneto-optical trap of metastable strontium for an optical lattice clock, Phys. Rev. A 101, 013420 (2020).
  46. Y. Wang, S. Shevate, T. M. Wintermantel, M. Morgado, G. Lochead, and S. Whitlock, Preparation of hundreds of microscopic atomic ensembles in optical tweezer arrays, npj Quantum Inf. 6, 54 (2020).
  47. B. J. Lester, N. Luick, A. M. Kaufman, C. M. Reynolds, and C. A. Regal, Rapid production of uniformly filled arrays of neutral atoms, Phys. Rev. Lett. 115, 073003 (2015).
  48. N. R. Hutzler, L. R. Liu, Y. Yu, and K.-K. Ni, Eliminating light shifts for single atom trapping, New J. Phys. 19, 023007 (2017).

Outline

Information

Phys. Rev. Research 7, 043050– Published 15 October, 2025
  • Received 31 January 2025
  • Accepted 14 July 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