Apply the action of this Kraus quantum operation upon a density

def evolve(self, rho: Density) -> Density:
        """Apply the action of this Kraus quantum operation upon a density"""
        qubits = rho.qubits
        results = [op.evolve(rho) for op in self.operators]
        tensors = [rho.tensor * w for rho, w in zip(results, self.weights)]
        tensor = reduce(add, tensors)
        return Density(tensor, qubits)