Summary: We extend two rigorous results of M. Aizenman et al. in their pioneering paper [Commun. Math. Phys. 112, 3–20 (1987; Zbl 1108.82312)] on the Sherrington-Kirkpatrick spin-glass model without external magnetic field to the quantum case with a “transverse field” of strength \(\mathsf{b}\). More precisely, if the Gaussian disorder is weak in the sense that its standard deviation \(\mathsf{v} > 0\) is smaller than the temperature \(1/\beta\), then the (random) free energy almost surely equals the annealed free energy in the macroscopic limit and there is no spin-glass phase for any \(\mathsf{b}/\mathsf{v} \geq 0\). The macroscopic annealed free energy turns out to be non-trivial and given, for any \(\beta \mathsf{v} > 0\), by the global minimum of a certain functional of square-integrable functions on the unit square according to a Varadhan large-deviation principle. For \(\beta \mathsf{v} < 1\) we determine this minimum up to the order \((\beta \mathsf{v})^4\) with the Taylor coefficients explicitly given as functions of \(\beta \mathsf{b}\) and with a remainder not exceeding \((\beta \mathsf{v})^6/16\). As a by-product we prove that the so-called static approximation to the minimization problem yields the wrong \(\beta \mathsf{b}\)-dependence even to lowest order. Our main tool for dealing with the non-commutativity of the spin-operator components is a probabilistic representation of the Boltzmann-Gibbs operator by a Feynman-Kac (path-integral) formula based on an independent collection of Poisson processes in the positive half-line with common rate \(\beta \mathsf{b}\). Its essence dates back to [M. Kac, Rocky Mt. J. Math. 4, 497–509 (1974; Zbl 0314.60052)], but the formula was published only in [“Dirac equation path integral: Interpreting the Grassmann variables”, Il Nuovo Cimento D 11, Paper No. 31, 31-39 (1989; doi:10.1007/BF02450232)] by B. Gaveau and L. S. Schulman.