Étudiant-chercheur étoile September 2015

Solomon Akaraka Owerre

PhD student in Physics
Université de Montréal

Award-winning publication: Macroscopic quantum tunneling and quantum-classical phase transitions of the escape rate in large spin systems

Published in: Physics Reports


"In this research we discussed recent theoretical and experimental developments on macroscopic quantum tunneling and phase transitions in spin systems. We reviewed different theoretical approaches to the problem of spin tunneling in single molecule magnets and exchange coupled dimer models. It is now understood that the suppression of tunneling at zero magnetic field for half-odd integer spin system is independent of the coordinate representation but only depends on the WZ or Berry phase term. Theoretically, it is still an open problem to determine the necessary conditions in which classical degenerate ground state for half-odd integer spin implies degenerate ground states in the pure quantum case. In the presence of a magnetic field along the spin hard anisotropy axis, tunneling is not suppressed for half-odd integer spins but rather oscillates with the field in accordance with the experimental observations."

The understanding of nature and its components continues to be an active research area in science. The current research presents a review on the theoretical and the experimental developments on macroscopic quantum tunneling and quantum–classical phase transitions of the escape rate in large spin systems. It also predicts new results which are yet to be corroborated experimentally. Furthermore, it provides adequate information on how electrons interact and reorganize due to quantum fluctuations. This effect is based on new technologies such as quantum computers, magnetic chips in our credit cards, debit cards, magnetic doors and refrigerators. It has a significant impact on our understanding of nature, its components and functionality.