{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"e5d320b8f900010c848c360896585093c42cc180d7cebb1ed3952ea2b8681b35","created":"2026-10-03T07:17:59Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"60ec841fea5eb1120c407b1ccc0977cbd8ca7594f247549d787c6878e786531a","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"cm.floquet-dtc.prethermal-dtc-short-range","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"Without disorder, a fast drive can still keep a time crystal alive for a time that grows exponentially with drive frequency, but theory says this needs long-range interactions or at least two dimensions. Existing observations used long-range or dipolar interactions.","posed_since":"2017","precise":"For a periodically driven spin lattice with short-range couplings of strength $J$, drive frequency $\\omega >> J/\\hbar$ and near-$\\pi$ spin flips, prethermal theory (Else, Bauer, Nayak, PRX 7, 011026, 2017) predicts period-doubled response lasting t* ~ exp(c hbar omega/J); at finite energy density this needs spontaneous breaking of an emergent Ising symmetry of the prethermal Hamiltonian, hence $d \\ge 2$ for short-range couplings. Does a $d = 2$ short-range system show t* growing exponentially with $\\omega$, and does the response vanish above the critical energy density of the prethermal Ising transition? Answer yes or no, with t*(omega).","problem_ref":null,"references":"","settled_by":"Measurement in a 2D Rydberg or superconducting-qubit array, or large-scale numerics, of the period-doubled lifetime versus $\\omega$ and initial energy density.","status_note":"Observed with long-range interactions in a trapped-ion chain (Kyprianidis et al., Science 2021) and with dipolar couplings in 3D nuclear-spin ensembles (Beatrez et al., Nature Physics 2023; Stasiuk et al., PRX 2023); a 2D short-range test is not known (low confidence).","title":"Prethermal time crystal in a clean short-range two-dimensional lattice","topic_ref":"45ec164defd4bbc53dbeb596072003667a3d92ea5f1f4be6270906a1a4927f9e"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"a8b4857e61dbcfc526a2ad7e3847124ac6c5ba7d69b007e1ee9847bf1c439ac2","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"be6fe0719e891528de2de57b66765cd81145d92dcf482fc48a9eeaeb6ccf3c26","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"ZSfONbwP_nRUljMrEswucpsDx6m17mpWabO1Z-d_JNM_rGdqetFmzfY3rZm8dzix69v6KAndUc0y460M1p_GCA"},"schema":"pubphys.envelope/1"},"record_hash":"a8b4857e61dbcfc526a2ad7e3847124ac6c5ba7d69b007e1ee9847bf1c439ac2","leaf_index":993}