Wei-Xiao Sun

Phantom Codes: Hardness, Rate Optimal qLDPC Constructions, and Distance Limits

An $[[n,k,d]]$ stabilizer code is phantom if every in-block logical CNOT gate can be realized by a permutation of its physical qubits. This eliminates the large and complicated physical overhead normally required for logical entangling gates. Yet this symmetry is highly restrictive: phantom codes are rare, the number o...