{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"99a4f1f79c25ee43725ead901d92bf9e6a28ad0c5268e0b0006f3cdff48df4c2","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["6c66ab1a106356b497801ed4117f947f1c83bf31fbbfb22c54b8cbab57fb20ba","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"b21524a62880d0c8df5d03d46763632a1e7ec367382b4571191ebf04da41d487","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"qi.macro-superpositions.levitated-nanoparticle-superposition","kind":"well-posed","literature_status":"open","n":"2","parents":[],"plain":"A glass bead about a hundred nanometers across can be held by laser light and cooled to its lowest quantum state of motion. The next step is a superposition of two places farther apart than the bead's own size, confirmed by interference.","posed_since":"","precise":"For an optically or magnetically levitated dielectric particle of mass about $10^{-15} \\text{ to } 10^{-14}\\,\\mathrm{g}$ (radius $r \\sim 5 \\times 10^{-6} \\text{ to } 10^{-5}\\,\\mathrm{cm}$) prepared near its motional ground state, create a coherent spatial superposition or wave packet with coherence length exceeding $r$, and verify coherence by interference fringes or Wigner-function negativity, since position variance alone does not distinguish coherent from incoherent spreading.","problem_ref":"6c66ab1a106356b497801ed4117f947f1c83bf31fbbfb22c54b8cbab57fb20ba","references":"","settled_by":"Release-and-recapture or inverted-potential interferometry showing center-of-mass interference fringes from a separation larger than r.","status_note":"In 2024 a ground-state-cooled nanoparticle's coherence length was increased more than threefold (arXiv:2408.01264) and a pre-cooled nanoparticle's motional state was expanded beyond its size (arXiv:2408.09596); no interference fringes at separations above the particle size were found in the literature checked.","title":"Spatial superposition of a levitated nanoparticle larger than its size","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"3f7ce13acec6a16f9f5afec35cf0cf2a69b7a61bfe95bfff6306e14c3668fac2","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"b33ddc1cae2105586651e75831c050a11cc2892ce6b756e0592beebd4a6c4db5","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"VT3XBqPBTlIPUUNj600yALpPmuGQioepdw_2Ngg0-skqgJPjKIH5e8IQQEVcGrhvOVPiOYR0YpaRkLTFNhK3Ag"},"schema":"pubphys.envelope/1"},"record_hash":"3f7ce13acec6a16f9f5afec35cf0cf2a69b7a61bfe95bfff6306e14c3668fac2","leaf_index":3726}