Quantum correlations and thermal machines

  • Adam Hewgill

Student thesis: Doctoral ThesisDoctor of Philosophy


Quantum mechanics has given us a new playground in which to experiment that boasts several unique features. In this thesis, we explore it in the context of thermodynamics: looking at what kind of thermal devices can be constructed and how quantum behaviour affects them. We consider three research strands. In the first part we formulate a selection of heat engines with two-qubit systems, utilising environments that induce quantum correlations into the system. We see that these correlations can have some effects on the work of the engine, but this effect is system dependent.

Describing the dynamics of a quantum system in contact with an external environment is often achieved with a master equation. When considering systems comprised of multiple subsystems, the description becomes more complicated and some of the master equations that have been used previously produce unphysical results. In the second part of this thesis we show that if one does the proper analysis of the microscopic derivation of these master equations, then no thermodynamical inconsistencies occur.

When one considers a system connected to three or more environments, a whole new set of possible thermodynamical machines becomes available. One notable case of these is the absorption refrigerator, which performs refrigeration without the need for an external work source. For the third part, we show how one can construct an absorption refrigerator using a three-qubit system with two-body interactions and describe its operation. We also show some thermal control properties of the three-qubit system.
Date of AwardJul 2020
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SupervisorGabriele De Chiara (Supervisor) & Alessandro Ferraro (Supervisor)

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