First and second sound in a dilute Bose gas across the BKT transition
We study the propagation of the two sound modes in two-dimensional Bose gases across the Berezinksii–Kosterlitz–Thouless transition using classical-field dynamics, which is motivated by recent measurements of Christodoulou et al (2021 Nature 594 191). Based on the dynamic structure factor (DSF), we...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2022-01-01
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| Series: | New Journal of Physics |
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| Online Access: | https://doi.org/10.1088/1367-2630/ac7d6f |
| _version_ | 1797748362278076416 |
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| author | Vijay Pal Singh Ludwig Mathey |
| author_facet | Vijay Pal Singh Ludwig Mathey |
| author_sort | Vijay Pal Singh |
| collection | DOAJ |
| description | We study the propagation of the two sound modes in two-dimensional Bose gases across the Berezinksii–Kosterlitz–Thouless transition using classical-field dynamics, which is motivated by recent measurements of Christodoulou et al (2021 Nature 594 191). Based on the dynamic structure factor (DSF), we identify the two sound modes as the Bogoliubov (B) and the non-Bogoliubov (NB) sound mode below the transition, and as the diffusive and the normal sound mode above the transition. The NB sound mode velocity is higher than the B sound mode velocity, which we refer to as the weak-coupling regime of the sound modes. We excite the sound modes by driving the system as in the experiment and by perturbing the density with a step-pulse perturbation, as a secondary comparison. The driven response depends on the driving strength and results in higher velocities for the B sound mode at high temperatures near the transition, compared to the sound results of the DSF and step-pulse excitation. We show that the higher mode velocity has a weak temperature dependence across the transition, which is consistent with the experimental observation. |
| first_indexed | 2024-03-12T16:04:36Z |
| format | Article |
| id | doaj.art-732f3afdb1f3440f9af5d23432253738 |
| institution | Directory Open Access Journal |
| issn | 1367-2630 |
| language | English |
| last_indexed | 2024-03-12T16:04:36Z |
| publishDate | 2022-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | New Journal of Physics |
| spelling | doaj.art-732f3afdb1f3440f9af5d234322537382023-08-09T14:26:20ZengIOP PublishingNew Journal of Physics1367-26302022-01-0124707302410.1088/1367-2630/ac7d6fFirst and second sound in a dilute Bose gas across the BKT transitionVijay Pal Singh0https://orcid.org/0000-0001-8881-978XLudwig Mathey1Zentrum für Optische Quantentechnologien and Institut für Laserphysik, Universität Hamburg , 22761 Hamburg, Germany; Institut für Theoretische Physik, Leibniz Universität Hannover , Appelstraße 2, 30167 Hannover, GermanyZentrum für Optische Quantentechnologien and Institut für Laserphysik, Universität Hamburg , 22761 Hamburg, Germany; The Hamburg Centre for Ultrafast Imaging , Luruper Chaussee 149, 22761 Hamburg, GermanyWe study the propagation of the two sound modes in two-dimensional Bose gases across the Berezinksii–Kosterlitz–Thouless transition using classical-field dynamics, which is motivated by recent measurements of Christodoulou et al (2021 Nature 594 191). Based on the dynamic structure factor (DSF), we identify the two sound modes as the Bogoliubov (B) and the non-Bogoliubov (NB) sound mode below the transition, and as the diffusive and the normal sound mode above the transition. The NB sound mode velocity is higher than the B sound mode velocity, which we refer to as the weak-coupling regime of the sound modes. We excite the sound modes by driving the system as in the experiment and by perturbing the density with a step-pulse perturbation, as a secondary comparison. The driven response depends on the driving strength and results in higher velocities for the B sound mode at high temperatures near the transition, compared to the sound results of the DSF and step-pulse excitation. We show that the higher mode velocity has a weak temperature dependence across the transition, which is consistent with the experimental observation.https://doi.org/10.1088/1367-2630/ac7d6fultracold atom superfluidsBerezinksii–Kosterlitz–Thouless transitionfirst and second soundcollective modes |
| spellingShingle | Vijay Pal Singh Ludwig Mathey First and second sound in a dilute Bose gas across the BKT transition New Journal of Physics ultracold atom superfluids Berezinksii–Kosterlitz–Thouless transition first and second sound collective modes |
| title | First and second sound in a dilute Bose gas across the BKT transition |
| title_full | First and second sound in a dilute Bose gas across the BKT transition |
| title_fullStr | First and second sound in a dilute Bose gas across the BKT transition |
| title_full_unstemmed | First and second sound in a dilute Bose gas across the BKT transition |
| title_short | First and second sound in a dilute Bose gas across the BKT transition |
| title_sort | first and second sound in a dilute bose gas across the bkt transition |
| topic | ultracold atom superfluids Berezinksii–Kosterlitz–Thouless transition first and second sound collective modes |
| url | https://doi.org/10.1088/1367-2630/ac7d6f |
| work_keys_str_mv | AT vijaypalsingh firstandsecondsoundinadilutebosegasacrossthebkttransition AT ludwigmathey firstandsecondsoundinadilutebosegasacrossthebkttransition |