{"schema":"pubphys.bundle/1","record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"398923e916bc2f52b14c35578df1a0c95146b6b962c0044b65ecc913ab92b30b","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b","d2728294983978acc523d07354f121efdf14ff6d3af22175f72b62f2baf83f74"],"salt":"960bad0b95a82786529efe13b8345398611917804b869690c24b9324adb87da8","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"cm.cuprates.twisted-trsb","kind":"well-posed","literature_status":"contested","n":"2","parents":[],"plain":"Stacking two thin flakes of the cuprate Bi2Sr2CaCu2O8+x rotated by 45 degrees is predicted to create a superconducting state whose pairs circulate in one sense, breaking time-reversal symmetry; Josephson experiments by different groups disagree.","posed_since":"2021","precise":"For c-axis Josephson junctions between Bi2Sr2CaCu2O8+x flakes twisted by $\\theta$ near 45 degrees, pure $d_{(x^2-y^2)}$ pairing makes the first-order Josephson coupling vanish, and second-order coupling is predicted to stabilize a $d + i d$ state with spontaneous time-reversal breaking (Can et al., Nature Physics 2021). Determine whether the critical current $I_c(\\theta)$ is suppressed at 45 degrees as pure d-wave requires, and whether half-integer Shapiro steps, a Josephson diode effect and spontaneous magnetization near 45 degrees arise from time-reversal breaking rather than from interface disorder or an s-wave admixture. An answer is a reproducible $I_c(\\theta)$ on junctions with characterized interfaces plus a direct probe of time-reversal breaking at 45 degrees.","problem_ref":"d2728294983978acc523d07354f121efdf14ff6d3af22175f72b62f2baf83f74","references":"","settled_by":"Independent groups measuring $I_c(\\theta)$ on atomically sharp junctions, with local magnetometry or polar Kerr detection (or exclusion) of spontaneous time-reversal breaking at $\\theta = 45\\,\\mathrm{degrees}$.","status_note":"Zhao et al. (Science 2023) reported a Josephson diode effect and half-integer Shapiro steps near 45 degrees, while Zhu et al. (PRX 2021, PRB 2023) found Josephson tunneling persisting at 45 degrees across the doping dome and attributed it to s-wave pairing.","title":"Does 45-degree twisted $\\mathrm{Bi2Sr2CaCu2O8}+x$ break time-reversal symmetry?","topic_ref":null},"content_withheld":"false","files":[],"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"f57403bd9a7a18aa06827c735e7fa103f54834bb4700fc2943dae5a045c2112f","schema":"pubphys.attested/1"},"id_token":null,"id_token_withheld":"false","envelope":{"attested_hash":"fa5d575a2300799d3d7c3637f7d4bb783be01666a14ecab193a17c14a098cf5d","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"JlagM5eM3HXpcED87ImGPk2MTsXA8Dam5_c73VFlLx5vWgdTWlFDiVyP-nZMWVSqxdQ2UfAlGfhvrKGD1L3DCg"},"schema":"pubphys.envelope/1"},"ots":{"attested":["AE9wZW5UaW1lc3RhbXBzAABQcm9vZgC_ieLohOiSlAEI-l1XWiMAeZ09fDY399S7eDvgFmahTsqxk6F8FKCYz13wIPpmBvAGGr0lSVRsFBIbFA3aoDTd3AikNDE3UAwgS29QCPAgb2JZ6yZvUOQs8nyw2sNHdCQzHVpn1h0VAGaRF5CToYwI8CCgREre6wYAEXBIonWbP8Oi-fOFKGv5RT8dyKCML0sx0QjxIEh0utbI2uYKIkzEPuJyUzv3vecxVe3Wy1tfaPt443FqCPAgyPoIxaouw9cYM_tJ1An7VaxGnbLBkR4O49bNEuCP05gI8SC-tKcgBscltf39qqvFXDW9FeXZ0N1z6gJlQnFYoXuTHQjwICHA10i6bPvZ9I1Ag67qE-LPAlaVdbccRYSx1XHhVLRDCPEgLknXQLPBphDVPQ2JIPapNIpNFDYAu57cOPZiO3xVZPcI8SBFZ7nkuh-5IaK75jNF2I3u9gWIJeTINL1f_rXWP5TwxwjxIK8CKI34eu_sgR6N3zB1SKGijO7ko6-mgEUnS-DdScYBCP_wCOf1iajMfCj1CPAQnjpoz1kO_dN22pXdltGw2AjxIE4XykgsZ_WSh2vkwqZCzoJ33eOitoafeDpQ-3_6R7A_CPAg4b6CYztt395HgCIMw1-W5LfG-vu-JwtH6wIGvmq0bZwI8CCtU0WsKh5BwLGGWacTQHMeBHwdClkCV-rMMMXN9ZvwZQjxBGrRZZPwCNknZwX9zuTwAIPf4w0u-QyOLCtodHRwczovL2JvYi5idGMuY2FsZW5kYXIub3BlbnRpbWVzdGFtcHMub3Jn8Aj1kxLXPF3sgQjwEN3TRaAlnRGdywLUXJqL_hoI8SC_EwWue7sXTkhbkg2KtpDc5URgyM3Hol8HHDVDiM8uLgjxBGrRZZLwCDbPE8C0jkmw_wCD3-MNLvkMji4taHR0cHM6Ly9hbGljZS5idGMuY2FsZW5kYXIub3BlbnRpbWVzdGFtcHMub3JnCPEgcCe_goUV_i6JgQUm8vGIzFLLPxWjAk_iuhN8MP2HtsgI8CCPm2C9s0XubFI_iMYYTrp7NQVEucjiDVVOS-5XhW0I8AjwILGVzUe4o5G4eCfsNghhwOFziij306RNYES910HKmhrsCPAgVyONoXyQM0NgJkZo0hKVGO9f4juKf5A3CyvglhBsUm8I8CCeXSTiCzsu5jmLW6aIc74nszLe4FOEslRZChj0t1VKtAjxIDr4W3XX8r8aow1ZiGRWxWoIW9dJhunhLwmguwsGdTO-CPEgELz-YATskE_flI3EMFwbuOgsnBRGkzF1Xa9I7rj-MQ4I8SB7TgKiPXFKLsITxTCqIEY2E_JnlB0P9hnCf6F5J05tTgjxIGB0NKCvdVTHWPyb-krv47MzDAWBd4vLje6N98K_6F_kCPAgyX4-cC3jGOgERVTj6eTI3Q0pFr0C9fiQQx-WUXIglL0I8VkBAAAAAfPitX67BAWDTZtWcQxQWCkh0YqMzi1a4gPWRNWeuOKwAAAAAAD-____AlREAgAAAAAAFgAUEXKzahzT5T5tisLdW6UYvM0Pl9sAAAAAAAAAACJqIPAEctMOAAgI8SAwkgFiLjrE4i4UPDMn2c7HXieBbkduCVR_rk5GmSghhwgI8CAeAZYQYIMdaCxzBP3Y06gnuz57Ns-TKJavZGdhkML93AgI8CC198zLIu74yxwmwNzR3PAaynBKuua9UCcw2CyBaEcKWAgI8CAxSXU58ENTCGnlVmMfBUDSe7PUXkdlNQkIcCczUvUXcwgI8CBK0rtRametS55XkRoTu4TTLoEsynoQA2atuGtOoQFm7wgI8CDktVbsge1QvmY068_HWE5N8syaqVDu30QVb4oO2shIhAgI8CAAGBdnq6kVTyqINAoW1AWmqSMrCXQ-zEzglSNUuUMpuQgI8CATBv3oWI6GOVvAjwYVlDhrkZfDGzhtR2pU4wqu0FZXfQgI8SCoGD7CnRzwIA9X2TonvAhr38a1B-laaGkTXOoVnKLalAgI8CDalktNU8YluuKLPRSEzK1gNVgBc6BCdYNysw57Ar07xwgI8SDGbdDDNu9PiyInO5tAadJPrtta_57FjBI8_UoOLsJpTAgI8SCbq51S51-NRozSBQVPKUoYMzKmPum0xMbTObF39PnJNwgI8CAyk4ieSMUJWnWk5mF9mfI8CXyF1YaYfNBysYuAvBIouAgIAAWIlg1z1xkBA_OmOw"],"envelope":["AE9wZW5UaW1lc3RhbXBzAABQcm9vZgC_ieLohOiSlAEIbRtkDGzDe6f88kv74iPVHkzlZPoHPvq-nMWgrW_cuUPwIG0dWyyl3OlyrA6YoFyEEkfrUm65p8Jo6dXrAoM72OXnCPEgpzXxkNUH61qHWl2ObU8Ap1QhAeRBULI0eQ-CPEgP6k0I8CBNFnxIZOZMMFfRcGUK_gBCFMPTxv3UIV_c1Xf8QCj3mAjxIA_dKXFv8PO7sDfgqE8wC8crjSv4joxRsze1rQK82IKbCPAgUmBzncrixG7TDnwHURz5xiwPIz2OdAbrkUa9jXf9DaEI8SD_5zFJHCmnJMVG3y8g48CODsGJwzCSeSjMybN-JiGepwjwICRMULf4Qk7B4Ixs-w5_AnqKLFYrm25Y_JDm1-0Q4j1tCPEgV483a5w_VdTK7my82rqJCPIXOvGhZNeRkwqfWifoP4MI8SBcP9hQb3hxUiLf8dFx-DuqZHA2xkmG-c_qCFt8QfQHCAjwIOv_x0B6HyZ6WMHKeIf_d_EUIvwPGdZeVY-hXN3RLDM5CPEgHd9u6OIGCvUV12A1B1xdiOprSJ-4w0cqwfe7CzVX5HsI8CDQo_sIWZiWXaTGRSQBLmU-lHJKskYKqsjO1r02DhB8LAj_8Ajn9YmozHwo9QjwEJ46aM9ZDv3TdtqV3ZbRsNgI8SBOF8pILGf1kodr5MKmQs6Cd93joraGn3g6UPt_-kewPwjwIOG-gmM7bd_eR4AiDMNfluS3xvr7vicLR-sCBr5qtG2cCPAgrVNFrCoeQcCxhlmnE0BzHgR8HQpZAlfqzDDFzfWb8GUI8QRq0WWT8AjZJ2cF_c7k8ACD3-MNLvkMjiwraHR0cHM6Ly9ib2IuYnRjLmNhbGVuZGFyLm9wZW50aW1lc3RhbXBzLm9yZ_AI9ZMS1zxd7IEI8BDd00WgJZ0RncsC1Fyai_4aCPEgvxMFrnu7F05IW5INiraQ3OVEYMjNx6JfBxw1Q4jPLi4I8QRq0WWS8Ag2zxPAtI5JsP8Ag9_jDS75DI4uLWh0dHBzOi8vYWxpY2UuYnRjLmNhbGVuZGFyLm9wZW50aW1lc3RhbXBzLm9yZwjxIHAnv4KFFf4uiYEFJvLxiMxSyz8VowJP4roTfDD9h7bICPAgj5tgvbNF7mxSP4jGGE66ezUFRLnI4g1VTkvuV4VtCPAI8CCxlc1HuKORuHgn7DYIYcDhc4oo99OkTWBEvddBypoa7AjwIFcjjaF8kDNDYCZGaNISlRjvX-I7in-QNwsr4JYQbFJvCPAgnl0k4gs7LuY5i1umiHO-J7My3uBThLJUWQoY9LdVSrQI8SA6-Ft11_K_GqMNWYhkVsVqCFvXSYbp4S8JoLsLBnUzvgjxIBC8_mAE7JBP35SNxDBcG7joLJwURpMxdV2vSO64_jEOCPEge04Coj1xSi7CE8UwqiBGNhPyZ5QdD_YZwn-heSdObU4I8SBgdDSgr3VUx1j8m_pK7-OzMwwFgXeLy43ujffCv-hf5AjwIMl-PnAt4xjoBEVU4-nkyN0NKRa9AvX4kEMfllFyIJS9CPFZAQAAAAHz4rV-uwQFg02bVnEMUFgpIdGKjM4tWuID1kTVnrjisAAAAAAA_v___wJURAIAAAAAABYAFBFys2oc0-U-bYrC3VulGLzND5fbAAAAAAAAAAAiaiDwBHLTDgAICPEgMJIBYi46xOIuFDwzJ9nOx14ngW5HbglUf65ORpkoIYcICPAgHgGWEGCDHWgscwT92NOoJ7s-ezbPkyiWr2RnYZDC_dwICPAgtffMyyLu-MscJsDc0dzwGspwSrrmvVAnMNgsgWhHClgICPAgMUl1OfBDUwhp5VZjHwVA0nuz1F5HZTUJCHAnM1L1F3MICPAgStK7UWpnrUueV5EaE7uE0y6BLMp6EANmrbhrTqEBZu8ICPAg5LVW7IHtUL5mNOvPx1hOTfLMmqlQ7t9EFW-KDtrISIQICPAgABgXZ6upFU8qiDQKFtQFpqkjKwl0PsxM4JUjVLlDKbkICPAgEwb96FiOhjlbwI8GFZQ4a5GX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