Pasqal 256-qubit processor shows unexpected slow relaxation in 2D quantum magnet
Pasqal and collaborators from the Flatiron Institute, the University of Augsburg, Forschungszentrum Jülich, the University of Regensburg and the Institut d'Optique-CNRS used a 256-qubit (physical) neutral-atom processor to study a 16x16 grid of atomic spins after a sudden quench. Depending on the applied field strength, the system settled in three ways; two were expected, while the third showed an abrupt slowdown in which it took far longer to settle than theory predicts. The team says it cannot yet explain this behavior. In that regime, three classical simulation methods diverged from the measurement and from each other, and the team says it modeled device noise and checked against exact calculations to confirm the effect was physical. The results are in an arXiv preprint that has not yet been peer reviewed, and Pasqal says they do not demonstrate computational quantum advantage.