Build repetition codes | IBM Quantum Learning

We can exploit additional ancilla qubits and entanglement to measure what are known as stabilizers that do not transform our encoded quantum information, while still informing us of some classes of errors that may have occurred. A quantum stabilizer code encodes kk logical qubits into nn physical qubits. Stabilizer codes critically focus on correcting a discrete error set with support from the Pauli group ΠnΠn. Assume the set of possible errors are ϵ⊂Πnϵ⊂Πn. For example, in a bit-flip code with three qubits encoding the quantum state, we will have ϵ={IIX,IXI,XII}ϵ={IIX,IXI,XII}. We can measure the stabilizers and observing their eigenvalues to dete