  We present a numerically exact Inchworm Monte Carlo method for equilibrium
multiorbital quantum impurity problems with general interactions and
hybridizations. We show that the method, originally developed to overcome the
dynamical sign problem in certain real-time propagation problems, can also
overcome the sign problem as a function of temperature for equilibrium quantum
impurity models. This is shown in several cases where the current method of
choice, the continuous-time hybridization expansion, fails due to the sign
problem. Our method therefore enables simulations of impurity problems as they
appear in embedding theories without further approximations, such as the
truncation of the hybridization or interaction structure or a discretization of
the impurity bath with a set of discrete energy levels, and eliminates a
crucial bottleneck in the simulation of ab initio embedding problems.
