Stability Experiments: The Overlooked Dual of Memory Experiments

Topological quantum computations are built on a foundation of two basic tasks: preserving logical observables through time and moving logical observables through space. Memory experiments, which check how well logical observables are preserved through time, are a well established benchmark. Strangely, there is no corresponding well established benchmark for moving logical observables through space. This paper tries to fill that gap with "stability experiments", which check how well a quantum error correction system can determine the product of a large region of stabilizers. Stability experiments achieve this by testing on a region that is locally a normal code but globally has a known product of stabilizers.