Thermodynamics and thermalization in superconducting quantum circuits

Modern superconducting circuits form open quantum systems that are coupled to their environment [1]. In our quantum thermodynamics experiments, we either couple the quantum circuits to engineered heat baths or investigate the dynamics of quasi-isolated superconducting quantum circuits. The first approach allows us to develop different types of quantum thermodynamic devices like quantum heat valves and rectifiers, refrigerators and heat engines, quantum thermometers, and ultrasensitive calorimeters [1,2]. In this talk my main focus is the concept of heat bath and thermalization in isolated quantum circuits. In particular I present the concept of quantum Poincare revivals in a system of coupled qubits [3,4]. At the end, I try to give an outlook towards interesting future challenges.

[1] Jukka P. Pekola and Bayan Karimi, Rev. Mod. Phys. 93, 041001 (2021); Steve Campbell et al., Quantum Science and Technology (2025)

[2] Bayan Karimi, Gorm Ole Steffensen, Andrew P. Higginbotham, Charles M. Marcus, Alfredo Levy Yeyati and Jukka P. Pekola, Nature Nanotechnology 19, 1613 (2024).

[3] J. P. Pekola, and B. Karimi, Entropy 26(5), 429 (2024).

[4] Bayan Karimi, Xuntao Wu, Andrew Cleland, and Jukka Pekola, arXiv:2508.13489 (2025).