  We report and characterize the emergence of a noise-induced state of quenched
disorder in a generic model describing a dense sheet of active polar disks with
non-isotropic rotational and translational dynamics. In this state, randomly
oriented self-propelled disks become jammed, only displaying small fluctuations
about their mean positions and headings. The quenched disorder phase appears at
intermediate noise levels, between the two states that typically define the
flocking transition (a standard disordered state that displays continuously
changing headings due to rotational diffusion and a polar order state of
collective motion). We find that the angular fluctuations in this dense system
follow an Ornstein-Uhlenbeck process leading to retrograde forces that oppose
self-propulsion, and determine its properties. Using this result, we explain
the mechanism behind the emergence of the quenched state and compute
analytically its critical noise, showing that it matches our numerical
simulations. We argue that this novel type of state could be observed in a
broad range of natural and artificial dense active systems with repulsive
interactions.
