En las fronteras de la Materia Condensada

Any attempt to revert the arrow of time would require the action of a qualified being or mechanisms called a Loschmidt daemon. We describe the experimental realizations of two of such creatures. One of them, the hasty daemon, is characterized for an instantaneous action of global effect: the change in the sign of the Hamiltonian. We discuss how the chaotic nature of a Hamiltonian dynamics leads to large scale quantum entangled state very fragile towards perturbations that degrades the fidelity of the evolution and prevents time reversal. There is an alternative stubborn daemon, who acts extramurally, but its persistent action reinjecting wave function amplitude is able to produce a full quantum state propagating backwards. We describe the mechanisms that would control his action.