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Abstract:
We study the decay of an atomic Bose–Einstein condensate (BEC) population N(τ) from the leaking boundaries of an optical lattice (OL). For a rescaled interatomic interaction strength Λ>Λb, discrete breathers (DBs) are created that prevent the atoms from reaching the leaking boundaries. Collisions of other lattice excitations with the outermost DBs result in avalanches, i.e. steps in N(τ), which for a whole range of Λ-values follow a scale-free distribution P(J=δN)~1/Jα. A theoretical analysis of the mixed phase space of the system indicates that 1<α<3, in agreement with our numerical findings
