In this second part of the thesis, we turn to the study of thermodynamics at the quantum scale, with a special focus on small thermal machines. To begin with, in Chapter 4, we look at the concept of a virtual temperature, as introduced in [43]. This is a temperature calculated for any pair of energy levels in a diagonal state by matching the ratio of its populations to the Gibbs state. The small quantum fridge introduced in Chapter 5, as well as all of the other small quantum thermal machines may be understood in terms of the virtual temperatures that they are able to generate within a system. We use the concept of virtual temperatures to construct an elegant and illuminating proof of the notion of complete passivity. A passive state [44] is one from which no work may be extracted from a unitary, while complete passivity refers to the property that no work can be extracted from multiple copies of a state.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:686187 |
| Date | January 2015 |
| Creators | Silva, Ralph Francisco |
| Publisher | University of Bristol |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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