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Experimental Investigation of a Bipartite Quench in a 1D Bose gas
by Léa Dubois, Guillaume Thémèze, Jérôme Dubail, Isabelle Bouchoule
Submission summary
| Authors (as registered SciPost users): | Isabelle Bouchoule · Jérôme Dubail · Léa Dubois |
| Submission information | |
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| Preprint Link: | https://arxiv.org/abs/2505.05839v2 (pdf) |
| Date submitted: | Oct. 31, 2025, 11:19 a.m. |
| Submitted by: | Jérôme Dubail |
| Submitted to: | SciPost Physics |
| Ontological classification | |
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| Academic field: | Physics |
| Specialties: |
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| Approaches: | Theoretical, Experimental |
Abstract
Long wavelength dynamics of 1D Bose gases with repulsive contact interactions can be captured by Generalized HydroDynamics (GHD) which predicts the evolution of the local rapidity distribution. The latter corresponds to the momentum distribution of quasiparticles, which have infinite lifetime owing to the integrability of the system. Here we experimentally investigate the dynamics for an initial situation that is the junction of two semi-infinite systems in different stationary states, a protocol referred to as `bipartite quench' protocol. More precisely we realise the particular case where one half of the system is the vacuum state. We show that the evolution of the boundary density profile exhibits ballistic dynamics obeying the Euler hydrodynamic scaling. The boundary profiles are similar to the ones predicted with zero-temperature GHD in the quasi-BEC regime, with deviations due to non-zero entropy effects. We show that this protocol, provided the boundary profile is measured with infinite precision, permits to reconstruct the rapidity distribution of the initial state. For our data, we extract the initial rapidity distribution by fitting the boundary profile and we use a 3-parameter ansatz that goes beyond the thermal assumption. Finally, we investigate the local rapidity distribution inside the boundary profile, which, according to GHD, presents, on one side, features of zero-entropy states. The measured distribution shows the asymmetry predicted by GHD, although unelucidated deviations remain.
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Author comments upon resubmission
List of changes
(We can provide the revised version of the manuscript with all changes visible in blue upon request.)
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In the introduction, we now mention the recent work [P. Schüttelkopf, M. Tajik, N. Bazhan, F. Cataldini, S.-C. Ji, J. Schmiedmayer and F. Møller, Characterising transport in a quantum gas by measuring drude weights, arXiv:2406.17569] where another bipartite protocol has been realized.
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In page 3, we no longer mention the estimate of the temperature of 100nK, and the discussion of the experimental setup has been improved.
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We have reorganized sections 3 and 4 for more clarity. Section 3 is now focused on the general theoretical prediction provided by Generalized Hydrodynamics, while Section 4 focuses on the zero-temperature (ground state) case.
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We have improved the discussion of potential effects due to transversely excited states in Figures 5 and 6 and in the text.
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The text in pages 10-12 has been improved so as to clarify the discussion.
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We added an appendix to explain the details of our attempts at reconstructing the rapidity distribution from the boundary profile.
Jerome Dubail on 2025-11-12 [id 6019]
Marked up manuscript in attachment
Attachment:
changes_in_blue.pdf