Robust fault tolerance for continuous-variable cluster states with excess antisqueezing

The immense scalability of continuous-variable cluster states motivates their study as a platform for quantum computing, with fault tolerance possible given sufficient squeezing and appropriately encoded qubits [N. C. Menicucci, Phys. Rev. Lett. 112, 120504 (2014)PRLTAO0031-900710.1103/PhysRevLett.112.120504]. Here, we expand the scope of that result by showing that additional antisqueezing has no effect on the fault-tolerance threshold, removing the purity requirement for experimental continuous-variable cluster-state quantum computing. We emphasize that the appropriate experimental target for fault-tolerant applications is to directly measure 15-17 dB of squeezing in the cluster state rather than the more conservative upper bound of 20.5 dB.