20 November 2015 Putting Quantum Systems to Work

ICFO researchers discover that quantum effects such as coherence and entanglement increase a system’s ability to store energy. Phys.org has recent highlighted the study “Extractable Work from Correlations”published in Physical Review X, in which ICFO researchers Martí Perarnau-Llobet, Karen V. Hovhannisyan, Marcus Huber and Paul Skrzypczyk, led by ICREA Prof. at ICFO Antonio Acín and in collaboration with the Université de Genève, have studied correlations among quantum systems and how to use them to optimally store work.

Work and quantum correlations are considered two fundamental resources in thermodynamics and quantum information theory. To understand how both resources can be interchanged, the team of researchers considered a set of correlated quantum particles which, when observed individually, are found at the same temperature. These particles are useless for thermodynamic purposes at the individual level, but correlations among them can be used to extract work. They then computed the maximum amount of work that can be extracted from such correlations, by considering general entangled states, separable states, and states with fixed entropy. Quantum properties such as coherence and entanglement were essential in this calculation.

The results they obtained showed that systems in which quantum effects are noticeable can store more energy than systems that are purely classical. However, they also saw that while entanglement gives an advantage for small quantum ensembles, this gain vanishes for a large number of systems.