Quantum Mechanics of Spins

Stefanie Czischek

Ciann‐Dong Yang, Hung-Jen Weng

This paper proposes a new mixed quantum mechanics (QM)-molecular mechanics (MM) approach, where MM is replaced by quantum Hamilton mechanics (QHM), which inherits the modeling capability of MM, while preserving the state-dependent nature of QM. QHM, a single mechanics playing the roles of QM and MM simultaneously, will be employed here to derive the three-dimensional quantum dynamics of diatomic molecules. The resulting state-dependent molecular dynamics including vibration, rotation and spin are shown to completely agree with the QM description and well match the experimental vibration-rotation spectrum. QHM can be incorporated into the framework of a mixed quantum-classical Bohmian method to enable a trajectory interpretation of orbital-spin interaction and spin entanglement in molecular dynamics.

Daniel Linnemann

Antonio Sciarretta

This paper aims at reproducing quantum mechanical (QM) spin and spin entanglement results using a realist, stochastic, and local approach, without the standard QM mathematical formulation. The concrete model proposed includes the description of Stern–Gerlach apparatuses and of Bell test experiments. Single particle trajectories are explicitly evaluated as a function of a few stochastic variables that they assumedly carry on. QM predictions are retrieved as probability distributions of similarly-prepared ensembles of particles. Notably, it is shown that the proposed model, despite being both local and realist, is able to violate the Bell–CHSH inequalities by exploiting the coincidence loophole and thus intrinsically renouncing to one of the Bell’s assumptions.

Michel Ghins

Back in 1964, Richard Feynman famously stated that "Nobody understands quantum mechanics."Indeed, despite its impressive empirical success, quantum mechanics (QM) remains the most perplexing and mind-boggling theory ever produced by humans.In his clear and thought-provoking book, Jean Bricmont advocates the merits of "the de Broglie-Bohm theory" and forcefully argues that it provides an intelligible picture of the quantum world out there.Being aware, however, that the de Broglie-Bohm theory is not immune from difficulties, the author acknowledges that understanding QM is an "unfinished story" (292). AQ1After a short introductory chapter, Bricmont discusses in Chapter 2 what he calls the "first mystery" of quantum mechanics, namely "interference and superpositions."Spin measurements with Mach -Zehnder interferometers ( § 2.2) show that the quantum state is a superposition of two incompatible states (spin up and spin down).When a measurement is takenperformed, the quantum state instantly collapses into one of the two states.Schrödinger's celebrated cat thought experiment was meant to show that believing in the existence of a superposition of states "cat alive" and "cat dead" before opening the box, simply is absurd (38).According to standard QM the evolution of 1✉ 1 Page 1 sur 5 e.

Derek W. Robinson