{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"cbf995fe1591836cfb9ff08d11e2cbb7f5f5f601441816016b9cc08b69b1b446","created":"2026-10-03T07:17:58Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"8851018aaa1c143acf9e77c95da8bd171c8cf98541ea93a0d2bda19c2b02d63b","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"cm.amorphous-low-temperature.ultrastable-depletion","kind":"well-posed","literature_status":"partially-resolved","n":"1","parents":[],"plain":"Glasses grown very slowly, for example by vapor deposition, can be far more stable than ordinary glasses, and some show far fewer tunneling defects or none detectable. Whether oxide glasses can be made free of them, and how fast their number drops with stability, is open.","posed_since":"","precise":"Vapor-deposited ultrastable indomethacin (Perez-Castaneda et al. 2014) shows strongly reduced tunneling-defect density, e-beam deposited hydrogen-free a-Si films showed no detectable tunneling states (Liu et al., Physical Review Letters 113, 025503, 2014), and simulations of glasses prepared by swap Monte Carlo find the defect density falling steeply with decreasing fictive temperature $T_f$ (Khomenko et al. 2020). Determine $P(T_f)$ for network glasses such as SiO2 and whether the a-Si result generalizes, i.e. whether $P \\to 0$ at finite $T_f$ or only in the ideal-glass limit.","problem_ref":null,"references":"","settled_by":"Low-temperature specific heat and internal friction on a family of ultrastable glasses with measured $T_{f}$, compared with simulations covering the same $T_{f}$ range.","status_note":"Tunneling-state-free a-Si films (2014), depleted ultrastable indomethacin (2014) and simulations (2020) show strong depletion; whether network oxides can be made defect-free is open.","title":"Can two-level systems be removed by making glasses more stable?","topic_ref":"d5ba98a0b7fd03c8a459d017fd4e5e33d6f390cd71005b8a63b71f0973f4abf6"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"26b990f95704da55626b45a88a918b049848d825c7df13440bd01c51ac0f159e","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"5b5ad1b3e4f9e7e3bacb8ef63c69271b46d95a62969dc4ea2df4bb43ac911679","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"NEpWQvLP8c3oL-1UEZHQL7phwpm02c4Loj27TopHXbl_QOpWegcGR0Q3TcrgFe56JozVwGCoQk6ifnKm92GwAg"},"schema":"pubphys.envelope/1"},"record_hash":"26b990f95704da55626b45a88a918b049848d825c7df13440bd01c51ac0f159e","leaf_index":907}