{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"f44126343e8d325884a8e91a82a951ebe8b4b6bc7c0ff6b882f1b82eb3242a70","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b","f9d5e291404e38224e1f97e59c4f73181555482ecbd088d175d956512c9c9ffc"],"salt":"b9152f266c1d6fca3bc5024f0fd65228a753e6e88753de7221a329b914062f65","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"amo.quantum-equivalence-principle.superposition-wep","kind":"well-posed","literature_status":"open","n":"2","parents":[],"plain":"Since energy has mass, an atom in a quantum superposition of two energy levels has no single definite mass. Whether it still falls exactly like a normal atom is a question that classical physics cannot pose.","posed_since":"2015","precise":"In the quantum formulation of the equivalence principle (Zych and Brukner, arXiv 1502.00971), the internal mass-energy operator $M = m_0 + H_{\\int}/c^2$ may couple to gravity through operators $M_g$ and $M_i$ that differ off-diagonally. Bound the off-diagonal violation parameters for atoms prepared in coherent superpositions of hyperfine or optical clock states at better than $10^{-12}$, improving on the about $10^{-9}$ bound of Rosi et al 2017.","problem_ref":"f9d5e291404e38224e1f97e59c4f73181555482ecbd088d175d956512c9c9ffc","references":"","settled_by":"An atom interferometer with test atoms in clock-state superpositions measuring the differential acceleration with sub-$10^{-12}$ precision.","status_note":"","title":"Do atoms in internal-energy superpositions obey the equivalence principle?","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"32faee8aea240bb2da5f8ad1415a061976f8875772badaee10ba3c9de7043d94","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"1ef190527d8d15a403e41109c48566b1c16223bc23e5cb3c290cf0496237f9c9","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"a-0u8ukmKsSMI5gs3a4BYiIQtf3bQ3cYDCJkSK3Ks4Dx8E5mg3Eu4nK_STyE69gqbM9PSRVRsAMS0xvVlctsBA"},"schema":"pubphys.envelope/1"},"record_hash":"32faee8aea240bb2da5f8ad1415a061976f8875772badaee10ba3c9de7043d94","leaf_index":2280}