Coherent Thermal Machines: Fluctuations and Performance

dc.contributorAalto Universityen
dc.contributor.authorMenczel, Paul
dc.contributor.departmentTeknillisen fysiikan laitosfi
dc.contributor.departmentDepartment of Applied Physicsen
dc.contributor.labQuantum Transport Groupen
dc.contributor.schoolPerustieteiden korkeakoulufi
dc.contributor.schoolSchool of Scienceen
dc.contributor.supervisorFlindt, Christian Prof., Aalto University, Department of Applied Physics, Finland
dc.descriptionA doctoral dissertation completed for the degree of Doctor of Science (Technology) to be defended, with the permission of the Aalto University School of Science, via remote connection on 11 November 2020 at 13:00. Remote connection link:
dc.description.abstractQuantum Engineering is a rapidly evolving discipline, promising the development of groundbreaking new technologies. To overcome the challenges posed by the nanoscopic scales and ultra-cold temperatures that are required for the implementation of quantum devices, understanding the thermodynamic interaction of these devices with their environment is important. Improving our knowledge of the laws of quantum thermodynamics enables engineers to exert better control over quantum circuits and it paves the way for more effective thermal management solutions on the nanoscale. In this dissertation, we focus on the study of thermal machines such as heat engines or refrigerators. These devices have recently been miniaturized in labs to the point where quantum effects can influence their performance. Due to the well-known advantages of quantum over conventional computers, it is natural to wonder whether coherence effects might be able to give a similar performance enhancement to thermal machines. Here, we approach this question on three different levels. First, we study the theory of periodically controlled open quantum systems in order to better understand the mathematical foundations of reciprocating thermal devices. Second, we investigate transport phenomena in open quantum systems, enabling us to discuss the fluctuations of thermodynamic currents and how they affect the performance of thermal machines. Third, and finally, we examine whether the performance of quantum heat engines is subject to universal bounds and how these bounds change in different operation regimes. The results of this thesis shed light on the optimal design of quantum devices, which will soon be ready for experimental implementation and investigation. Overall, we find that coherence leads to quantum friction, that is, to an increase in thermodynamic irreversibility with associated performance losses. In the adiabatic weak-coupling regime, these losses outweigh the benefits stemming from the increased number of degrees of freedom that are accessible in quantum setups. In other words, we find that coherence should generally be kept as small as possible in order to optimize the performance of nanoscale thermal machines in this regime. A promising direction for future investigations is to explore the effects of strong coupling and fast driving, where quantum advantages may be achievable.en
dc.format.extent68 + app. 92
dc.identifier.isbn978-952-64-0088-4 (electronic)
dc.identifier.isbn978-952-64-0087-7 (printed)
dc.identifier.issn1799-4942 (electronic)
dc.identifier.issn1799-4934 (printed)
dc.identifier.issn1799-4934 (ISSN-L)
dc.opnLutz, Eric, Prof., University of Stuttgart, Germany
dc.publisherAalto Universityen
dc.relation.haspart[Publication 1]: P. Menczel and K. Brandner. Limit cycles in periodically driven open quantum systems. J. Phys. A: Math. Theor. 52 43LT01, September 2019. DOI: 10.1088/1751-8121/ab435a
dc.relation.haspart[Publication 2]: F. Brange, P. Menczel, and C. Flindt. Photon counting statistics of a microwave cavity. Phys. Rev. B 99, 085418, February 2019. Full text in Acris/Aaltodoc: DOI: 10.1103/PhysRevB.99.085418
dc.relation.haspart[Publication 3]: S. Singh, P. Menczel, D. S. Golubev, I. M. Khaymovich, J. T. Peltonen, C. Flindt, K. Saito, É. Roldán, and J. P. Pekola. Universal First-Passage-Time Distribution of Non-Gaussian Currents. Phys. Rev. Lett. 122, 230602, June 2019. Full text in Acris/Aaltodoc: DOI: 10.1103/PhysRevLett.122.230602
dc.relation.haspart[Publication 4]: P. Menczel, C. Flindt, and K. Brandner. Quantum jump approach to microscopic heat engines. Phys. Rev. Research 2, 033449, September 2020. DOI: 10.1103/PhysRevResearch.2.033449
dc.relation.haspart[Publication 5]: P. Menczel, C. Flindt, and K. Brandner. Thermodynamics of cyclic quantum amplifiers. Phys. Rev. A 101, 052106, May 2020. Full text in Acris/Aaltodoc: DOI: 10.1103/PhysRevA.101.052106
dc.relation.haspart[Publication 6]: P. Menczel, T. Pyhäranta, C. Flindt, and K. Brandner. Two-stroke optimization scheme for mesoscopic refrigerators. Phys. Rev. B 99, 224306, une 2019. Full text in Acris/Aaltodoc: DOI: 10.1103/PhysRevB.99.224306
dc.relation.ispartofseriesAalto University publication series DOCTORAL DISSERTATIONSen
dc.revDe Chiara, Gabriele, Dr., Queen's University Belfast, UK
dc.revPerarnau-Llobet, Martí, Dr., Max-Planck-Institute of Quantum Optics, Germany
dc.subject.keywordstatistical physicsen
dc.subject.keywordquantum physicsen
dc.subject.keywordfluctuations and noiseen
dc.subject.keywordthermal machinesen
dc.subject.keywordopen quantum systemsen
dc.subject.keywordcounting statisticsen
dc.subject.keywordoptimization problemsen
dc.titleCoherent Thermal Machines: Fluctuations and Performanceen
dc.typeG5 Artikkeliväitöskirjafi
dc.type.ontasotDoctoral dissertation (article-based)en
dc.type.ontasotVäitöskirja (artikkeli)fi
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