 Norton’s quantum supertask requires a non-standard quantum system because the dynamical evolution he proposes is not unitary, even though it obeys a differential equation in wavefunction space that takes the form of the Schrödinger equation (Norton 1999, §5). Nevertheless, Norton’s quantum supertask has fruitfully appeared in physical applications, having been found to arise naturally in a framework for perturbative quantum field theory proposed by Duncan and Niedermaier (2013, Appendix B).