Improved bounds on collapse models from rotational noise of the Laser Interferometer Space Antenna Pathfinder mission

We study spontaneous wave-function collapse models, which modify the Schrödinger equation with nonlinear and stochastic terms offering a solution to the quantum measurement problem. We find that constraints on the phenomenological parameters of the continuous spontaneous localization (CSL) model can be tightened using the recent analysis of the Laser Interferometer Space Antenna Pathfinder mission’s angular motion data. We derived a stronger constraint on the CSL model than previously achieved with translational motion. Additionally, we identify general conditions under which rotational measurements provide an advantage over translational ones in testing collapse models. These results enhance the experimental strategies for probing fundamental modifications of quantum mechanics.