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Breakthrough study on exploring open quantum systems forms new theory
(19 April 2013)
A collaboration of research between Durham University’s Dr. Nikitas Gidopoulos, formerly of ISIS at the Rutherford Appleton Laboratory, and Dario Calvani, Alessandro Cuccoli and Paola Verrucchi (from Italy’s University of Florence, National Institute for Nuclear Physics-INFN, and National Research Council-CNR) has been published in a major US scientific journal.
The ‘Proceedings of the National Academy of Sciences’ reports how this breakthrough study has brought together two diametrically different approaches to exploring open quantum systems, and formed the underlying theory. This includes shedding light on the understanding of coherence between quantum systems or a quantum system and its environment.
Defined by Feynman as “a part of the Universe”, this ‘open system’ has until now been largely untapped, disguised by the rest of the system around it, the ‘environment’. However the researchers have found that the behaviour of the principle system (focus of attention) depends, is influenced and often driven by its surrounding environment and the links with it (correlations).
The purpose of the paper was to propose a way of describing this link more precisely. “Looking at popular science texts, one usually reads that quantum mechanics is the part of physics that describes the behaviour of very small things, like atoms and subatomic particles”, says Dr Gidopoulos, “but it’s not just very small things that have a deep quantum mechanical origin, but particles with much larger masses whose effects we experience daily and often take them granted as classical”.
Left: In this analogy the open system is the bee and the environment the flowers: details of the bees evidently emerge but we can no longer understand some aspects of their behaviour, such as the relation between their being still in a point and the fact that there is a flower underneath. Whereas the bottom image shows that a theoretical approach to open quantum systems is possible, that corresponds to a representation where every single detail of the bees image is kept, together with the relevant correlations between their behaviour and the structure of the flowering field they are flying upon.
The team have applied these conceptual tools to analyse a paradigmatic example in the study of open quantum systems, with a view to studying more realistic/complicated problems and most importantly to study the dynamics of open systems in relation to their environment.
This includes, for example, applying a magnetic field to a spin, an effect once taken as classical, whereas now the team have found how the correlations of the underlying quantum entanglement between system and environment manifest.
So what does this mean? Well, quantum correlations or entanglement may be used in order to control/drive a quantum system that is influenced by its environment (quantum information transfer/quantum transport.) Also, these conceptual tools have the potential to become widely used as a theoretical formalism/methodology to study open quantum systems.