  A long-standing open question about Gaussian continuous-variable cluster
states is whether they enable fault-tolerant measurement-based quantum
computation. The answer is yes. Initial squeezing in the cluster above a
threshold value of 20.5 dB ensures that errors from finite squeezing acting on
encoded qubits are below the fault-tolerance threshold of known qubit-based
error-correcting codes. By concatenating with one of these codes and using
ancilla-based error correction, fault-tolerant measurement-based quantum
computation of theoretically indefinite length is possible with finitely
squeezed cluster states.
