We study how coarse-graining procedure of an underlying UV-complete quantum gravity gives rise to a connected geometry. It has been shown, quantum entanglement plays a key role in the emergence of such a geometric structure, namely a smooth Einstein-Rosen bridge. In this paper, we explore the possibility of the emergence of similar geometric structure from classical correlation, in the AdS/CFT setup. To this end, we consider a setup where we have two decoupled CFT Hilbert spaces, then choose a random typical state in one of the Hilbert spaces and the same state in the other. The total state in the fine-grained picture is of course a tensor product state, but averaging over the states sharing the same random coefficients creates a geometric connection for simple probes. Then, the apparent spatial wormhole causes a factorization puzzle. We argue that there is a spatial analog of half-wormholes, which resolves the puzzle in the similar way as the spacetime half-wormholes.
Positivity of the gravitational path integral implies the axionic weak gravity conjecture
Leinweber Institute for Theoretical Physics and Department of Physics, University of California, Berkeley（加州大学伯克利分校莱因韦伯理论物理研究所与物理系）；RIKEN iTHEMS Center for Interdisciplinary Theoretical and Mathematical Sciences（理化学研究所 iTHEMS 跨学科理论与科学中心）；Joseph Henry Laboratories, Princeton University（普林斯顿大学约瑟夫·亨利实验室）；Department of Physics, Harvard University（哈佛大学物理系）
Quantum chaos transition in a two-site SYK model dual to an eternal traversable wormhole
Maldacena和Qi最近提出，二维Anti de Sitter空间（${\rm AdS}_2$）中的永恒可穿越虫洞是两个Sachdev-Ye-Kitaev（SYK）模型低温极限的引力对偶，并通过相关相互作用（我们称之为自旋算符）耦合。本文研究了这种耦合SYK模型的谱和本征态性质。我们已经发现，在频谱的尾部的水平统计，并为足够弱的耦合，随机矩阵理论表明，穿越虫洞不是量子混沌的显着偏差。相比之下，对于足够强的耦合，对应于黑洞阶段，水平统计很好地描述了随机矩阵理论。这一转变的水平统计大致符合以前报道的霍金-佩奇过渡弱耦合。我们已经明确表明，这种热力学转变变成一个尖锐的交叉耦合增加。同样地，该临界耦合也对应于基态和热场双态（TFD）之间的重叠最小的临界耦合。在严格对角化所能达到的尺寸范围内，基态仅在强耦合极限下才能很好地近似于TFD态。这是由于基态接近于自旋算符的本征态，而自旋算符的本征态对应于最低本征值，在无限温度下是精确的TFD态。在这个区域中，谱密度被分离成以自旋算符的本征值为中心的斑点。对于较弱的耦合，指数衰减系数在张量积的基础上，典型的TFD，成为幂律。最后，我们还发现，总哈密顿量有一个额外的离散对称性，这是以前没有报道过的。
