Floquet Control of Erratic‐Gauge Collective Pinning in a Non‐Hermitian Aubry–André–Harper Chain

We investigate Floquet control of a non‐Hermitian Aubry–André–Harper chain with a spatially fluctuating imaginary gauge field of zero mean. Under open boundary conditions, an exact nonunitary transformation maps the driven problem to its Hermitian counterpart, separating the Hermitian‐frame evolution from the gauge‐induced spatial reweighting of right‐state profiles. This structure distinguishes erratic‐gauge collective pinning from AAH localization with eigenstate‐dependent centers. High‐frequency driving tunes their crossover through the renormalized hopping. The real‐time dynamics shows a nonmonotonic response: intermediate driving enables spreading into the bulk followed by gauge‐induced concentration in an interior region, whereas stronger driving suppresses the underlying spreading. Comparison with the similarity‐matched Hermitian evolution directly separates these two contributions. Our results establish Floquet driving as a route to control collective pinning induced by spatially fluctuating imaginary gauge fields, and suggest a general strategy for manipulating erratic non‐Hermitian states.