Quantum heat diode

A nonlinear circuit element coupled asymmetrically to two heat baths acts as a nonreciprocal conductor of heat, i.e. as a heat diode. Here we present results on measurements of heat transport [1] through a superconducting transmon qubit coupled capacitively to two reservoirs. We employ similar bolometric techniques as in our recent experiment measuring Josephson radiation thermally [2]. We find that the heat current presents several peaks as a function of the qubit energy; the origin of these intriguing resonances is not fully understood currently. The heat current in forward and backward directions shows strong diode-like behaviour: it differs by almost a factor of two when the qubit energy is at its minimum value.



[1] Jukka P. Pekola and Bayan Karimi, Rev. Mod. Phys. 93, 041001 (2021).

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