Magnetic-Field-Induced Non-Gaussian Fluctuations in Macroscopic Equilibrium Systems

We calculate the magnetic-field-dependent nonlinear conductance and noise in a two-dimensional macroscopic inhomogeneous system. If the system does not possess a specific symmetry, the magnetic field induces a nonzero third cumulant of the current even at equilibrium. This cumulant is related to the first and second voltage derivatives of the spectral density and average current in the same way as for mesoscopic quantum-coherent systems, but these quantities may be much larger. The system provides a robust test of a nonequilibrium fluctuation relation.