At the nanoscale, electrons and atoms perform random thermal motion and can be subject to quantum effects. Can we use the kinetic energy of electrons to do useful work? Can quantum phenomena make energy conversion more efficient? We combine experiment and theory to explore the fundamentals of generating electricity from heat or light, and the use of information to generate work.
A device for studying highly efficient thermoelectric energy conversion in a quantum dot, embedded into a nanowire. This artwork made it on the cover page of Nature Nanotechnoloogy, October Issue 2018. Reference: Nature Nanotechn. 13, 920–924 (2018)
Thermoelectrics and hot carriers
Thermoelectricity uses a heat gradient in an electronic material to generate an electric current.
Nanoscale phenomena, such as energy filtering and a modified density of states in quantum dots or quantum wires, can be used to enhance the efficiency of thermal-to-electric energy conversion up to the Carnot limit. We explore and realize the fundamental limits of thermoelectric energy conversion. We also apply our insights to harvesting energy form non-equilibrium electrons, for example hot electrons in solar cells. In the long term, we aim to contribute to a sustainable society based on renewable energy.
Making use of fluctuations
The energetics of small systems, such as macromolecules or nanoelectronic systems, is in many ways different compared to macroscopic systems. For instance, systems on the micro- or nanoscales can exhibit substantial fluctuations in energy that must be considered in their thermodynamic descriptions. In systems driven out of equilibrium, fluctuations can even give important insights into the equilibrium properties of the systems. Stochastic thermodynamics is a relatively new branch of thermodynamics that provides a framework for the energetics of non-equilibrium small systems. We are aiming to develop a stochastic thermodynamics framework for (opto-)electronic devices, and to identify new, highly efficient ways of nanoscale energy conversion. We also combine theory and experiment to study fluctuation-driven transport phenomena in nanoelectronic systems.
Work per cycle of a many-boson Szilard engine (right panel), demonstrating a quantum advantage. Reference: Phys. Rev. Lett. 120, 100601 (2018).
Quantum Thermodynamics offers a novel perspective on the foundations of Statistical Mechanics and provides new tools to analyze, model and design nano-scale systems where quantum fluctuations strongly affect the physical properties. Harnessing quantum superposition and correlations for an improved performance of energy harvesting and conversion is an outstanding challenge in the field. Moreover, knowledge of Quantum Thermodynamics is of key importance to nanoscale and quantum information processing, where state read-out and initialization leads to information erasure, causing dissipation of energy. We are investigating fundamental properties of heat flow, work production and generation of entropy in quantum systems. We also combine theory and experiment to analyze quantum thermal machines operating at the nanoscale.
A quantum-dot heat engine operating close to the thermodynamic efficiency limits M. Josefsson, A. Svilans, A.M. Burke, E.A. Hoffmann, S. Fahlvik, C. Thelander, M. Leijnse, and H. Linke. Nature Nanotechn. 13, 920–924 (2018), DOI: https://doi.org/10.1038/s41565-018-0200-5.
See article quantum-dot heat engine at the publisher's site
Quantum Szilard Engine with Attractively Interacting Bosons J. Bengtsson, M. Nilsson Tengstrand, A. Wacker, P. Samuelsson, M. Ueda, H. Linke, and S. M. Reimann. Phys. Rev. Lett. 120, 100601, (2018), DOI: http://dx.doi.org/10.1103/PhysRevLett.96.154502
See article quantum Szilard engine at the publisher's site
Detailed Fluctuation Relation for Arbitrary Measurement and Feedback Schemes P.P. Potts, P. Samuelsson. Phys. Rev. Lett. 121, 210603 (2018).
See article detailed fluctuation relation at publisher's site
- Jakob Bengtsson
- Adam Burke
- Jonas Johansson
- Martin Leijnse
- Heiner Linke
- Ville Maisi
- Stephanie Reimann
- Peter Samuelsson
- Claes Thelander
- Andreas Wacker
Martin Josefsson, Quantum-Dot Heat Engines, PhD thesis, Lund University 2020
See Martin Josefsson's thesis at the Research Portal
Artis Svilans, Thermoelectric studies of nanowire-based quantum dots PhD thesis, Lund University 2018
See Artis Svilans' thesis at the Research Portal
I-Ju Chen,Thermally and Optically Excited Electron Transport in Semiconductor Nanowires, PhD thesis, Lund University 2018
See I-Ju Chen's thesis at the Research Portal
Regina Schmitt, Feedback in Small Systems - A Stochastic Thermodynamic Perspective, PhD thesis, Lund University 2018
See Regina Schmitt's thesis at the Research Portal