As current quantum devices grow more complex, the question of verification becomes increasingly important. Verification refers to tests carried out in order to ascertain how close a quantum device is to its ideal performance limit. This is especially critical for quantum computing and simulation architectures that are not yet error-corrected, which are often referred to as noisy intermediate scale devices. A powerful, and currently leading, method for such verification is to implement a specialized type of random evolution, which generates quantum states or operators that randomly fill the associated state space. However, this type of evolution is not available on many types of quantum devices, including most analog quantum simulators, which have been used to study outstanding questions in quantum many-body physics. To solve this issue, we propose to make use of a very recent and surprising observation: Viewed from the right perspective, generic chaotic many-body evolution will produce randomly distributed quantum states, even without specialized control sequences. We call this phenomenon emergent randomness. We propose to use emergent randomness as a widely available tool for device verification, thereby generalizing existing protocols to a much broader class of quantum devices as well as to shorter evolution times and illuminating the limitations of randomness-based verification more generally.
