Understand
We investigate boundaries of 3D color codes and provide a systematic classification into 101 distinct boundary types, including two novel classes.
- The first class consists of 1 boundary and is generated by sweeping the codimension-1 (2D) $T$-domain wall across the system and attaching it to the $X$-boundary that condenses only magnetic fluxes.
- Since the $T$-domain wall cannot condense on the $X$-boundary, a new magic boundary is produced, where the boundary stabilizers contain $XS$-stabilizers going beyond the conventional Pauli stabilizer formalism, and hence contains 'magic'.
- Neither electric nor magnetic excitations can condense on such a magic boundary, and only the composite of the magnetic flux and codimension-2 (1D) $S$-domain wall can condense on it, which makes the magic boundary going beyond the classification of the Lagrangian subgroup.