Vanishing critical magnetization in the quantum Ising model

Adapting the recent argument of Aizenman, Duminil-Copin and Sidoravicius for the classical Ising model, it is shown here that the magnetization in the transverse-field Ising model vanishes at the critical point. The proof applies to the ground state in dimension $d\geq2$ and to positive-temperature states in dimension $d\geq 3$, and relies on graphical representations as well as an infrared bound.