Quantenthermodynamik: Von Resourcentheorien zu offenen Quantensystemen und zurück
Optik, Quantenoptik und Physik der Atome, Moleküle und Plasmen
Theoretische Physik der kondensierten Materie
Zusammenfassung der Projektergebnisse
Phenonemological thermodynamics is an independent physical theory studying exchanges of energy and entropy of a system with its surrounding heat baths and work reservoirs. At the time of its inception, thermodynamic systems were macroscopically large, determined by a few mean values (energy, temperature, volume, etc.) with negligible fluctuations, and often close to equilibrium. Today, our increased nanotechnological abilities allow us to design and control systems, which are very small, dominated by fluctuations and far from equilibrium. Moreover, these systems are no longer only influenced by idealized heat baths and work reservoirs. In addition, experimentalists make use of much more sophisticated nonequilibrium resources such as (quantum) measurements, feedback control operations or specifically engineered environments. Under these circumstances it appears somewhat surprising that thermodynamic principles nevertheless apply even for the most sophisticated nanoengines. However, uncovering them requires to account for all the above mentioned additional difficulties in a consistent manner. During my fellowship I have contributed to these challenges in two different ways. First, I set up a consistent thermodynamic framework, which is applicable to a variety of quantum nanotechnologies and explicitly incorporates any ‘external interventions’ such as quantum measurements, feedback control operations, state preparations, etc. Importantly, I formulated the laws of thermodynamics in such a way that they can be applied to a single run of the experiment, thereby providing a quantum counterpart to the theory of classical stochastic thermodynamics. Whereas many proposals for such a ‘quantum stochastic thermodynamics framework’ already existed in the literature, my so-called ‘operational approach’ is uniquely characterized by the fact that it can take into account disturbance, measurement backaction, incomplete information and a variety of other experimental imperfections. This allowed me for the first time to give a thermodynamic interpretation of Nobel-prize-winning experiments, which were carried out in the group of Serge Haroche a few years ago. Second, I provided a unifying perspective on microscopic derivations of the second law in nanoscale systems. Such a microscopic derivation is important to correctly quantify irreversibility (and hence, also the efficiency of any potential engine) at the nanoscale since the phenonemological theory of thermodynamics does not tell us how to identify internal energy, heat, work or entropy under these circumstances. Most previous work in the field focused on characterizing heat and work exchanges without considering the perhaps most important (and clearly most astonishing) thermodynamic concept: entropy. By using a microscopic definition of thermodynamic entropy, which has its origin in the writings of Boltzmann, Gibbs, von Neumman, Wigner and others, I succeeded to derive a hierarchy of second laws for quantum nanotechnologies, which have a clear counterpart in the phenomenological theory of thermodynamics and which previously remained largely unnoticed. Moreover, each member of the hierarchy has a clear information theoretic interpretation. A further major consequence of this hierarchy is the outcome that all nanosystems in contact with finite heat baths are more efficient than we previously thought. Finally, I used the freedom provided by this fellowship to work on a book with the title “Quantum Stochastic Thermodynamics: Foundations and Selected Applications.” This book provides the first comprehensive, pedagogical and in-depth account of the rapidly evolving fields of (classical and quantum) stochastic thermodynamics, which open the door to understand and design thermodynamic processes at the nanoscale.
Projektbezogene Publikationen (Auswahl)
-
Operational approach to quantum stochastic thermodynamics, Phys. Rev. E 100, 022127 (2019)
P. Strasberg
-
Repeated interactions and quantum stochastic thermodynamics at strong coupling, Phys. Rev. Lett. 123, 180604 (2019)
P. Strasberg
-
Stochastic thermodynamics with arbitrary interventions, Phys. Rev. E 100, 022135 (2019)
P. Strasberg and A. Winter
-
Thermodynamics of Quantum Causal Models: An Inclusive, Hamiltonian Approach, Quantum 4, 240 (2020)
P. Strasberg
