Dynamics of the Ising Spin-Glass Model in a Transverse Field

We use quantum Monte Carlo methods and various analytic approximations to solve the Ising spin-glass model in a transverse field in the disordered phase. We focus on the behavior of the frequency dependent susceptibility of the system above and below the critical field . We establish the existence of an exact equivalence between this problem and the single-impurity Kondo model at the quantum critical point. Our predictions for the long-time dynamics of the model are in good agreement with experimental results on $LiHo_{0.167}Y_{0.833}F_4$.