Spectroscopy of the two unequal superconducting resonators coupled via transmon qubit for the realization of the quantum heat engine*

Progress in both superconducting circuit QED experiments and ultrasensitive nanoscale bolometry provide a unique platform for studying heat transport in the quantum limit, towards the realization of quantum heat engines and refrigerators [1,2]. Transmon qubits coupled to superconducting resonators have been considered as promising candidates for realizing such quantum systems, such as the recently demonstrated quantum heat valve [3]. This work is devoted to study both theoretically and experimentally the transmission spectrum of the resonator-qubit-resonator assembly, in both the equal (valve) and unequal (engine) resonators regimes. For the realization of the quantum heat engine, we study the flux-tunable photonic heat transport in the resonator-qubit-resonator assembly with unequal resonators terminated by mesoscopic normal-metal reservoirs. Additionally, a means to characterize a superconducting resonator shunted with a highly dissipative normal metal bolometer is presented.
References:
[1] R. Kosloff and A. Levy, Annual Rev. Phys. Chem. 65, 365 (2014).
[2] B. Karimi and J. P. Pekola, Phys. Rev. B 94, 184503 (2016).
[3] A. Ronzani et al., Nature Physics 14, p.991 (2018).