Link between quantum entanglement and thermalization

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Theoretical physicists from Trinity College Dublin have found a deep link between quantum entanglement and thermalization, which is the process in which something comes into thermal equilibrium with its surroundings.

Professor Goold elaborates: “When you prepare a cup of coffee and leave it for a while it will cool down until it reaches the temperature of its surroundings. This is thermalization. In Physics we say that the process is irreversible. How irreversibility and thermal behaviour emerges in physical systems is something which fascinates me as a scientist as it applies on scales as small as atoms, to cups of coffee, and even to the evolution of the universe itself. In Physics, statistical mechanics is the theory which aims at understanding this process from a microscopic perspective. For quantum systems the emergence of thermalization is notoriously tricky and is a central focus of this current research.

However, what we show in our work is that not only is entanglement present in the process, but its structure is very different depending on which way you choose to describe your system. So, it gives us a way to test foundational questions in statistical mechanics. The idea is general and can be applied to a range of systems as small as a few atoms and as large as blackholes.

The numerical simulations for this project have been done at the limit of what can currently be done at the level of high-performance computing (HPC). 

The study has been published in Physical Review Letters. (

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