CTAMOP member unveils the thermodynamic arrow of time

Last updated May 30, 2017 by Andrew Brown

Nuclear Spins point to arrow of time
Irreversibility is a key concept in physics: the breaking of time-reversal at the macroscopic level ? exemplified in a striking way by the second law of thermodynamics ? goes against the intuition provided by the intrinsic symmetry of the microscopic equations of motion that govern elementary processes at the atomic scale. So whence does the so called “arrow of time” emerge?

Mauro Paternostro, Professor of Quantum Optics and Quantum Information and member of the Quantum Technology Group at Queen’s (QTeQ), as part of an international team comprising researchers at CBPF (Rio de Janeiro, Brazil), Universidade Federal do ABC (Santo André, Brazil) and the University of Erlangen Nuernberg (Germany), has addressed the emergence of the thermodynamic arrow of time by studying experimentally the non-equilibrium dynamics of a liquid NMR sample driven by time-gated microwave pulses. The team has shown that the process driving an initial equilibrium state of the sample towards a non-equilibrium final state is fundamentally and provably different from the reversed “backward” process: I.E. inverting the sign (direction) of time is definitely not sufficient, as witnessed by the emergence of a thermodynamic entropy associated with such a lack of reversibility.

The study has been published in the prestigious pages of Phys. Rev. Lett., where it has been selected as an Editors’ Choice and featured in a “Viewpoint” article, authored by Dr. Alexia Auffeves (Institut Neel, Grenoble).

This is only the most recent outcome of the “Thermodynamics of quantum processes” project conducted at CTAMOP by members of QTeQ, who are leading the European network, TherMiQ. This project has received 2.5M Euros from the EU FP7 to investigate the thermodynamics of mesoscopic quantum systems, a burgeoning field in which CTAMOP is an international leader.


We are a Research Cluster of the School of Mathematics and Physics at Queen’s University Belfast in Northern Ireland. Our research interests are focused primarily on computational and theoretical physics.

Old Physics Building

The Old Physics Building,
where CTAMOP is situated.