Thesis defence N.H.Y. Ng: quantum systems

29 March 2017 | 15:00
location: Aula, TU Delft
by Webredactie

A Theory of Thermodynamics for Nanoscale Quantum Systems. Promotor: Prof.dr. S.D.C. Wehner (EWI).

Thermodynamics is one of the main pillars of theoretical physics, and it has a special appeal of having wide applicability to a large variety of different physical systems. However, many assumptions in thermodynamics apply only to systems which are bulk material, i.e. consisting a large number of microscopic classical particles. The central aim of this thesis is to construct a theory of thermodynamics that holds for nanoscale quantum systems, even those as small and simple as a single qubit. We do this by starting out from the core basics of quantum theory: unitary dynamics on closed quantum systems. With a framework that naturally adopts the first law as an energy preserving condition, we show refinement of the laws of thermodynamics. In particular, the second law is refined in the quantum nanoregime: instead of having the free energy as the sole quantity dictating the possibility of a thermodynamic state transition, a whole family of generalized free energies also constitute necessary conditions for the occurrence of a transition.

We also apply our findings to analyze the maximum achievable efficiency for quantum heat engines. Although quantum heat engines may achieve the Carnot efficiency, we find additional restrictions that surface in the study of quantum nanoscale heat engines, which are a direct consequence of the generalized second laws. This has provided us with a deeper understanding into the fundamental limitations of how efficient devices can be made in the realm of microscopic quantum systems.

More information?
For access to theses by the PhD students you can have a look in TU Delft Repository, the digital storage of publications of TU Delft. Theses will be available within a few weeks after the actual thesis defence. 

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