{"paper":{"title":"Observing the emergence of a velocity hierarchy in matter waves","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["quant-ph"],"primary_cat":"cond-mat.quant-gas","authors_text":"Hanns-Christoph N\\\"agerl, Igor Zhuravlev, Laurent Sanchez-Palencia, Manuele Landini, Milena Horvath, Sudipta Dhar, Thierry Giamarchi, Wenhan Chen, Xudong Yu, Yanliang Guo, Yi Zeng","submitted_at":"2026-08-05T14:24:25Z","abstract_excerpt":"Classical waves in dispersive media naturally exhibit distinct phase and group velocities. Whether an analogous separation of velocities can emerge in matter waves under strong many-body interactions has remained experimentally unexplored. Here, we demonstrate the emergence of a velocity hierarchy in a strongly interacting lattice gas. Using quench spectroscopy together with time-resolved correlation measurements, we independently determine the sound, group, and phase velocities across the superfluid-to-Mott-insulator transition. These velocities are nearly degenerate close to the transition, "},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2608.05241","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2608.05241/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}