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MA: Fachverband Magnetismus
MA 26: Focus Session: Unconventional Thermoelectric Phenomena and Materials (joint session MA/TT)
MA 26.3: Invited Talk
Wednesday, March 20, 2024, 16:00–16:30, H 1058
Nonlocal heat engines with hybrid quantum dot systems — •Rafael Sánchez1, Mojtaba S. Tabatabaei2, David Sánchez3, and Alfredo Levy Yeyati1 — 1Dep. Física teórica de la materia condensada and Ifimac, Universidad Autónoma de Madrid, Madrid, Spain — 2Department of Physics, Kharazmi University, Tehran, Iran — 3Institute for Cross-Disciplinary Physics and Complex Systems IFISC (UIB-CSIC), Palma de Mallorca, Spain
The energy absorbed by a conductor from a non-equilibrium environment can be rectified to generate finite electrical power. Typically, this depends on tiny energy-dependent asymmetries of the device, formed by e.g. a quantum dot [1]. We show that larger currents are expected in hybrid systems, where a superconductor hybridizes the even-parity states in the quantum dot [2]. We consider the environment to consist on a quantum dot Coulomb-coupled to the conductor and tunnel-coupled to a hot reservoir. Two main mechanisms contribute to the generation of power. On one hand, the non-equilibrium charge fluctuations in the second dot correlate with the Andreev processes, hence injecting Cooper pairs in the superconductor. This provides the necessary symmetry breaking energy transfer. On the other hand, this mechanism competes with quasiparticle contributions, which benefit from the sharp features of the superconducting density of states, and is able to increase the engine performance [3].
[1] H. Thierschmann et al., Nature Nanotech. 10, 854 (2015)
[2] S. M. Tabatabaei et al., Phys. Rev. Lett. 125, 247701 (2020)
[3] S. M. Tabatabaei et al., Phys. Rev. B 106, 115419 (2022)
Keywords: Quantum thermoelectrics; Hybrid normal-superconductor junctions; Quantum dots; Quantum heat engines