Two-Qubit Operations for Finite-Energy Gottesman-Kitaev-Preskill Encodings

Phys Rev Lett. 2024 Sep 6;133(10):100601. doi: 10.1103/PhysRevLett.133.100601.

Abstract

We present techniques for performing two-qubit gates on Gottesman-Kitaev-Preskill (GKP) codes with finite energy, and find that operations designed for ideal infinite-energy codes create undesired entanglement when applied to physically realistic states. We demonstrate that this can be mitigated using recently developed local error-correction protocols, and evaluate the resulting performance. We also propose energy-conserving finite-energy gate implementations which largely avoid the need for further correction.