Stabilizing a Continuous Family of Non-classical Grid States in an Oscillator

Non-classical states of light are a valuable resource for quantum information processing, but they are fragile and decohere due to unwanted interactions with their environment. In particular, grid states based on the Gottesman-Kitaev-Preskill (GKP) code enable novel strategies for quantum transduction, communication, sensing, and error correction. In this work, we expand the breadth of these resources by extending the GKP code to a continuous family of codes, parametrized by the phases of the code stabilizers. We experimentally stabilize this code family for the case of a one-dimensional code space, where a single non-classical grid state of an oscillator is stabilized for each choice of the stabilizer phases. By measuring the Wigner function of this light after 10,000 stabilization rounds, corresponding to a duration of about 63 ms that is much longer than all timescales present in our physical system, we demonstrate that these non-classical states are stable in the steady state. Our work highlights the strength and flexibility of bosonic quantum error correction for stabilizing non-classical states of light against decoherence.