The Eastin–Knill theorem is a no-go theorem that states: "No quantum error correcting code can have a continuous symmetry which acts transversely on physical qubits". In other words, no quantum error correcting code can transversely implement a universal gate set. Since quantum computers are inherently noisy, quantum error correcting codes are used to correct errors that affect information due to decoherence. Unfortunately, error corrected data has to be decoded in order to perform gates on the qubits. Decoding the data makes it prone to errors. Fault tolerant quantum computation bypasses this by performing gates on encoded data. Transversal gates can be used to perform fault tolerant but not universal quantum computation by guaranteeing that errors don't spread uncontrollably through the