Enlarging the GKP stabilizer group for enhanced noise protection

Abstract: Encoding a qubit in a larger Hilbert space of an oscillator is an efficient way to protect its quantum information against decoherence. Promising examples of such bosonic encodings are the Gottesman-Kitaev-Preskill (GKP) codes. In this work, we investigate how redefining the stabilizer group of the GKP codes to include all operations with trivial action on the code space can contribute to the search for an optimal implementation of a logical circuit when it is affected by noise. We find the generators of the Gaussian stabilizer group, allowing us to search for different physical implementations of a Clifford operation. We then propose an algorithm that finds the optimal implementation of a given logical Clifford circuit on GKP codes, such that the state is less affected by loss errors during the computation. Finally, we demonstrate numerically, with logical randomized benchmarking, that such a compiler can increase the lifetime of square-GKP qubits while running Clifford circuits, compared to a random walk compiler.