{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"c749a66ef3ecb6e2d2cbd4f6473c628df3901494fe35bc7124b7421a43a8be60","created":"2026-10-03T07:17:53Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"34b02a26d5478777113f0f84193d69dc7f44d9fcecbe9d7111c59fbec1f9f901","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"amo.cavity-photon-matter.photon-crystal","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"Theory predicts that photons slowed in a Rydberg atom cloud can repel so strongly that they line up like a crystal. This has not been seen for more than a few photons.","posed_since":"2013","precise":"Rydberg electromagnetically induced transparency medium with blockade radius $R_{b}$ and optical depth per blockade radius $\\mathrm{OD}_{b}$. Predicted crystalline order of polaritons (Otterbach et al., PRL 2013). Measure n-photon correlations g^(n)(tau_1,...) showing periodic order across at least 3 photons. Answer: observed or ruled out at accessible $\\mathrm{OD}_{b}$.","problem_ref":null,"references":"","settled_by":"Multi-photon correlation measurements showing periodic density order for three or more photons.","status_note":"","title":"Crystallization of photons in Rydberg media","topic_ref":"8df59b7655cdc4331866853909e22dff07fb2d661e37f2a43fdc664ddd9f7dda"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"b222ece2d5b92e3fefb12170a98ad32df64981761061bd249eb0a979dbae751b","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"4629bd62b6de3f192a3ed8069a5563cbead8e0bc34ef43fbe4407eef273a65b0","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"EOgIJlYldITCDxRn9-dfBdiM83m_ufJpPO15OZv5-U25EcM3mxSUZpLuvqzwfqO_0UWyxCMreo5qS06ffQ9eBQ"},"schema":"pubphys.envelope/1"},"record_hash":"b222ece2d5b92e3fefb12170a98ad32df64981761061bd249eb0a979dbae751b","leaf_index":385}