{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"0a64d4a79b9643afc3a3b8fc57534c5925dbb39f0805a867994ae02e344a56e1","created":"2026-10-03T07:18:10Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011","c98bc365982ccf041c16ecefa2e9bbcf3c1ba198726ef75107771a435bdeb2b8"],"salt":"4057ad7950f74f81a04237017d45a542171889a89cacd57aa7049862f81392f3","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"qi.tunneling-arrival-time.larmor-opaque-barrier","kind":"well-posed","literature_status":"open","n":"1","parents":[{"note":"","parent_revision":"c98bc365982ccf041c16ecefa2e9bbcf3c1ba198726ef75107771a435bdeb2b8","relation":"special_case"}],"plain":"The Hartman effect predicts that the tunneling delay stops growing as the barrier gets thicker, which would imply speeds above that of light. Cold-atom experiments that use an atom's spin as a built-in clock can now test this.","posed_since":"1962","precise":"For cold atoms (e.g. 87Rb) tunneling through an optical barrier with an internal-state Larmor clock, measure the transmitted-atom Larmor times $\\tau_y$ and $\\tau_z$ versus barrier width $L$ in the opaque regime $\\kappa L >> 1$, $\\kappa = \\sqrt{2 m (V_0 - E)} / \\hbar$, and determine whether they saturate with $L$ as the Hartman effect predicts for the phase delay.","problem_ref":null,"references":"","settled_by":"A Larmor-clock measurement over a range of $L$ reaching $\\kappa L$ of several, with transmission high enough to resolve the precession.","status_note":"Larmor times of about 0.6 ms were measured for rubidium atoms in 2020, and their decrease at lower incident energy was reported in 2021 (arXiv:2101.12309).","title":"Does the Larmor tunneling time saturate for thick barriers?","topic_ref":"358768349f8fe9b49e5942c4fef2bbf2a089805f474e2a5f2d52d216a641711f"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"ee6afdb7fc7f83f867a39a484cfe21738bcd045d27946ece4a956ae8bac63505","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"e6a5aced639700ed50688986ad0df07af5ffdb27f455d765fdb73e278e8022fe","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"UVwm0eSjBX_qLcF9_DPkRj40rMih5l-JOFp6QNmA7XUFOJLX62mBhtM7YLS0_ExsegCY5merWLvCioUQd9qBDg"},"schema":"pubphys.envelope/1"},"record_hash":"ee6afdb7fc7f83f867a39a484cfe21738bcd045d27946ece4a956ae8bac63505","leaf_index":2060}