Moiré superlattices^1,2 have recently emerged as a platform upon which correlated physics and superconductivity can be studied with unprecedented tunability^3,4,5,6. Although correlated effects have been observed in several other moiré systems^{7,8,9,10,11,12,13,14,15,16,17}, magic-angle twisted bilayer graphene remains the only one in which robust superconductivity has been reproducibly measured^4,5,6. Here we realize a moiré superconductor in magic-angle twisted trilayer graphene (MATTG)¹⁸, which has better tunability of its electronic structure and superconducting properties than magic-angle twisted bilayer graphene. Measurements of the Hall effect and quantum oscillations as a function of density and electric field enable us to determine the tunable phase boundaries of the system in the normal metallic state. Zero-magnetic-field resistivity measurements reveal that the existence of superconductivity is intimately connected to the broken-symmetry phase that emerges from two carriers per moiré unit cell. We find that the superconducting phase is suppressed and bounded at the Van Hove singularities that partially surround the broken-symmetry phase, which is difficult to reconcile with weak-coupling Bardeen–Cooper–Schrieffer theory. Moreover, the extensive in situ tunability of our system allows us to reach the ultrastrong-coupling regime, characterized by a Ginzburg–Landau coherence length that reaches the average inter-particle distance, and very large T_BKT/T_F values, in excess of 0.1 (where T_BKT and T_F are the Berezinskii–Kosterlitz–Thouless transition and Fermi temperatures, respectively). These observations suggest that MATTG can be electrically tuned close to the crossover to a two-dimensional Bose–Einstein condensate. Our results establish a family of tunable moiré superconductors that have the potential to revolutionize our fundamental understanding of and the applications for strongly coupled superconductivity.

莫尔超晶格^1,2最近已成为一个平台，可以在其上以前所未有的可调性^3,4,5,6研究相关物理和超导性。尽管在其他几个莫尔系统^{7、8、9、10、11、12、13、14、15、16、17}中观察到相关效应，但魔角扭曲双层石墨烯仍然是唯一可重现稳健超导性的材料测量^4,5,6。在这里，我们实现了魔角扭曲三层石墨烯 (MATTG) 中的莫尔超导体¹⁸，其电子结构和超导特性的可调性比魔角扭曲双层石墨烯更好。作为密度和电场函数的霍尔效应和量子振荡的测量使我们能够确定系统在正常金属状态下的可调相界。零磁场电阻率测量表明，超导性的存在与每个莫尔晶胞的两个载流子出现的对称破缺相密切相关。我们发现超导相在部分围绕破缺对称相的范霍夫奇点处受到抑制和限制，这很难与弱耦合 Bardeen-Cooper-Schrieffer 理论相协调。而且，T _BKT / T _F值，超过 0.1（其中T _BKT和T _F分别是 Berezinskii-Kosterlitz-Thouless 转变和费米温度）。这些观察结果表明，MATTG 可以电调谐到接近二维玻色-爱因斯坦凝聚体的交叉点。我们的结果建立了一系列可调谐莫尔超导体，它们有可能彻底改变我们对强耦合超导的基本理解和应用。