One of the first theoretically predicted manifestations of strong interactions in many-electron systems was the Wigner crystal^1,2,3, in which electrons crystallize into a regular lattice. The crystal can melt via either thermal or quantum fluctuations⁴. Quantum melting of the Wigner crystal is predicted to produce exotic intermediate phases^5,6 and quantum magnetism^7,8 because of the intricate interplay of Coulomb interactions and kinetic energy. However, studying two-dimensional Wigner crystals in the quantum regime has often required a strong magnetic field^9,10,11 or a moiré superlattice potential^12,13,14,15, thus limiting access to the full phase diagram of the interacting electron liquid. Here we report the observation of bilayer Wigner crystals without magnetic fields or moiré potentials in an atomically thin transition metal dichalcogenide heterostructure, which consists of two MoSe₂ monolayers separated by hexagonal boron nitride. We observe optical signatures of robust correlated insulating states at symmetric (1:1) and asymmetric (3:1, 4:1 and 7:1) electron doping of the two MoSe₂ layers at cryogenic temperatures. We attribute these features to bilayer Wigner crystals composed of two interlocked commensurate triangular electron lattices, stabilized by inter-layer interaction¹⁶. The Wigner crystal phases are remarkably stable, and undergo quantum and thermal melting transitions at electron densities of up to 6 × 10¹² per square centimetre and at temperatures of up to about 40 kelvin. Our results demonstrate that an atomically thin heterostructure is a highly tunable platform for realizing many-body electronic states and probing their liquid–solid and magnetic quantum phase transitions^4,5,6,7,8,17.

多电子系统中强相互作用的第一个理论预测表现之一是维格纳晶体^1,2,3，其中电子结晶成规则晶格。晶体可以通过热波动或量子波动⁴熔化。由于库仑相互作用和动能之间错综复杂的相互作用，预计维格纳晶体的量子熔化会产生奇异的中间相^5,6和量子磁性^{7,8 。}然而，在量子区域研究二维维格纳晶体通常需要强磁场^9,10,11或莫尔超晶格势能^12,13,14,15，从而限制了对相互作用电子液体的完整相图的访问。在这里，我们报告了在原子级薄的过渡金属二硫化物异质结构中观察到的没有磁场或莫尔电位的双层维格纳晶体，该异质结构由两个由六方氮化硼隔开的MoSe _{2单层组成。}我们在低温下两个 MoSe ₂层的对称（1:1）和不对称（3:1、4:1 和 7:1）电子掺杂下观察到稳健相关绝缘态的光学特征。我们将这些特征归因于由两个互锁的相称三角形电子晶格组成的双层维格纳晶体，由层间相互作用稳定¹⁶. ^{维格纳晶相非常稳定，在每平方厘米高达 6 × 10 12}的电子密度和高达约 40 开尔文的温度下会发生量子和热熔化转变。我们的结果表明，原子级薄的异质结构是一个高度可调的平台，可用于实现多体电子态并探测它们的液-固和磁量子相变^4,5,6,7,8,17。