| （英） |
Quantum error correction (QEC) is a crucial building block for realizing quantum computers. Continuous-variable
(CV) based QEC codes offer hardware-efficient implementation by leveraging the infinite dimension of harmonic oscillators.
While CV-QEC codes are generally characterized by rotation and translation symmetries, translation symmetric codes, e.g.,
Gottesmann-Kitaev-Preskill (GKP) and squeezed cat codes, are highly robust to photon loss errors. However, the computation
accuracy is restricted by the available squeezing level for state preparation; the squeezing level also degrades during computation. Here, after revealing that a linear combination of displacement operators with periodic displacement values constitute the
projector onto the code space for the translation symmetric bosonic codes, we introduce the virtual projective squeezing (VPS)
method, which allows for the computation of expectation values corresponding to the higher squeezing level in an error-mitigation
manner with quite shallow randomly generated quantum circuits. We also point out that the linear-combination-of-unitaries
(LCU) methods can be used to physically raise the squeezing level of quantum states, not only for expectation values with more
efficient sampling cost. Nevertheless, the VS method is significantly more hardware-friendly than the LCU method because it
requires constant depth regardless of the target squeezing level and the code constructions, and it is also compatible with other
error mitigation strategies. We have uploaded the full version of our work in Ref. [1]. |