  In this paper, we investigate the error correction of universal Gaussian
transformations obtained in the process of continuous-variable quantum
computations. We have tried to bring our theoretical studies closer to the
actual picture in the experiment. When investigating the error correction
procedure, we have considered that both the resource GKP state itself and the
entanglement transformation are imperfect. In reality, the GKP state has a
finite width associated with the finite degree of squeezing, and the
entanglement transformation is performed with error. We have considered a
hybrid scheme to implement the universal Gaussian transformations. In this
scheme, the transformations are realized through computations on the cluster
state, supplemented by linear optical operation. This scheme gives the smallest
error in the implementation of universal Gaussian transformations. The use of
such a scheme made it possible to reduce the oscillator squeezing threshold
required for the implementing of fault-tolerant quantum computation schemes
close to reality to -19.25 dB.
