Continuous-variable error correction for general Gaussian noises

Abstract

Quantum error correction is essential for robust quantum information processing with noisy devices. As bosonic quantum systems play a crucial role in quantum sensing, communication, and computation, it is important to design error correction codes suitable for these systems against various different types of noises. While most efforts aim at protecting qubits encoded into the infinite dimensional Hilbert space of a bosonic mode, [Phys. Rev. Lett. 125, 080503 (2020)] proposed an error correction code to maintain the infinite-dimensional-Hilbert-space nature of bosonic systems by encoding a single bosonic mode into multiple bosonic modes. Enabled by Gottesman-Kitaev-Preskill states as ancilla, the code overcomes the no-go theorem of Gaussian error correction. In this work, we generalize the error correction code to the scenario with general correlated and heterogeneous Gaussian noises, including memory effects. We introduce Gaussian pre-processing and post-processing to convert the general noise model to an independent but heterogeneous collection of additive white Gaussian noise channels and then apply concatenated codes in an optimized manner. To evaluate the performance, we develop a theory framework to enable the efficient calculation of the noise standard deviation after the error correction, despite the non-Gaussian nature of the codes. Our code provides the optimal scaling of the residue noise standard deviation with the number of modes and can be widely applied to distributed sensor-networks, network communication and composite quantum memory systems.