Commentary on “A simple, practical experiment to investigate atomic wavefunction reduction within a Stern‐Gerlach magnet” by Michael Devereux, published in J. Phys. B: At. Mol. Opt. Phys. 57, 152501 (2024), https://doi.org/10.1088/1361‐6455/ad5992

Abstract

I believe I have never before addressed a scientific paper with nonacademic language, but for reasons which I hope I can make clear below, I allow myself in this Commentary to go beyond scientific language.Prof. Devereux has been attempting for quite a number of years to claim that coherent Stern-Gerlach (SG) splitting is impossible. For example, he claimed that "Einsteinian relativity, and the understanding of Schrödinger evolution applicability through a static potential, forbid continuation of a spin superposition through the Stern-Gerlach field." 1 While I am convinced that trying to oppose the mainstream paradigm is an essential part of doing science and therefore welcome such attempts, I am weary of attempts that are made without proper arguments. Prof. Devereux tried to present his arguments in person in a workshop in Frankfurt in 2019 when the SG lab was declared an EPS Historic Site, and once again was unable to make any proper argument to support his point of view. Now, he is publishing rather bizarre theoretical arguments stating "Thus, wavefunction development in the Stern-Gerlach magnet is discontinuous when the atom absorbs real energy from the magnet. Discontinuity in wavefunction evolution implies a loss of interference downstream of the S-G magnet." I will let the community judge the veracity of his theoretical arguments. 2 I decided to write this commentary not because of all of the above, but because this time Prof. Devereux has also wandered into the experimental realm, explaining why previous SG interferometry experiments, and specifically my group's experiments, are in fact not proving that coherent SG splitting is possible. Doing so without a proper understanding of these decade-long experiments is regrettable.