  We study transport across a magnetic impurity by means of a recently
developed slave-spin technique that does not require any constraint. Within a
conserving mean-field approximation we find a conductance that displays both
the known zero-bias anomaly but also the expected peak at bias of order U. We
extend the slave-spin mean-field approximation to study the out of equilibrium
transient evolution of a quantum dot. We apply the method to investigate the
time-evolution of a quantum dot induced by a time-dependent electrochemical
potential applied to the contacts. Similarly to the time-dependent Gutzwiller
approximation, the mean-field slave-spin dynamics is able to capture
dissipation in the leads, so that a steady-state is reached after a
characteristic relaxation time.
