Encoding of baby-universe degrees of freedom in the CFT state

Characterize precisely how the baby universe arising in the non-handlebody AdS3 geometry is encoded in the two-dimensional holographic CFT state, including developing a quantitative map between topological operators in the baby universe and moduli-changing operations in the boundary CFT.

Background

In pure AdS3 gravity, the baby universe Hilbert space is an auxiliary space associated with Virasoro conformal blocks in Virasoro TQFT. The mixed state constructed by the authors entangles two asymptotically AdS universes with this auxiliary Hilbert space.

While qualitative features indicate that moduli of the boundary Riemann surface influence the auxiliary state, the precise encoding map from the CFT to baby-universe degrees of freedom remains to be quantitatively established.

References

The extent to which we can declare that the baby universe is encoded in the CFT state remains unclear. But we leave for future work a quantitative analysis of the encoding.

— Baby Universes in AdS$_3$  (2512.02098 - Belin et al., 1 Dec 2025) in Section 3, Subsection “Interpretation of the baby universe state and VTQFT”