  We construct Carrollian scalar field theories in general dimensions, mainly
focusing on the boundaries of Minkowski and Rindler spacetime, whose quantum
flux operators form a faithful representation of Carrollian diffeomorphism up
to a central charge, respectively. At future/past null infinity, the fluxes are
physically observable and encode rich information of the radiation. The central
charge may be regularized to be finite by the spectral zeta function or heat
kernel method on the unit sphere. For the theory at the Rindler horizon, the
effective central charge is proportional to the area of the bifurcation surface
after regularization. Moreover, the zero mode of supertranslation is identified
as the modular Hamiltonian, linking Carrollian diffeomorphism to quantum
information theory. Our results may hold for general null hypersurfaces and
provide new insight in the study of the Carrollian field theory, asymptotic
symmetry group and entanglement entropy.
