Postgraduate @ Aalto University 

Monday June 27 – 8.45 BST

Effect of high impedance environment on photonic heat transport

Due to the fast growth of quantum technologies, heat transport, regardless of its carriers in such systems, has become an intensive subject of study. This work focuses on studying microwave photon-mediated heat transport and its deviation from the quantum limit in systems with a small Josephson junction immersed into a high impedance environment. The variations of the quantum limit are due to Coulomb blockade effects caused by the high impedance environment. For our purpose, the environment’s resistance is greater than the resistance quantum 6.45 KΩ. Therefore, these platforms are suitable for studying exchange heat between the two environments, thanks to the correspondence between Plank’s black body radiation and Johnson-Nysquist noise yielding from the resistive elements. Photonic heat transport in this type of superconducting circuit has been studied theoretically [1-4] and experimentally [5,6] in the low impedance regime. The experimental work succeeded by Meschke et al. [5] was demonstrated heat conductance due to photons. However, the maximum limit imposed by the universal quantum limit of thermal conductance did not reach due to the impedance mismatch provided by the element used to tune the heat flow. Afterward, Timofeev et al. [6] experimentally demonstrated the vital role of impedance matching to get the heat transport quantum limited. In the present work, we study phenomena that limit quantum heat conductance when a better impedance matching for a tunable circuit such as Ref [5] is implemented. We have obtained the photonic heat conduction closer to the quantum limit by introducing higher impedance resistors. 

1.      D. R. Schmidt, R. J. Schoelkopf, and A. N. Cleland, Photon-mediated thermal relaxation of electrons in nanostructures, Phys. Rev. Lett. 93, 045901 (2004). 
2.      T. Ojanen and A. P. Jauho, Mesoscopic photon heat transistor, Phys. Rev. Lett. 100, 155902  (2008). 
3.      L. M. Pascal, H. Courtois, and F. W. Hekking, Circuit approach to photonic heat transport, Phys. Rev. B 83, 125113 (2011). 
4.      G. Thomas, J. P. Pekola, and D. S. Golubev, Photonic heat transport across a Josephson junction, Phys. Rev. B 100, 94508 (2019). 
5.      M. Meschke, W. Guichard, and J. P. Pekola, Single-mode heat conduction by photons, Nature 444, 187 (2006). 
6.      A. V. Timofeev, M. Helle, M. Meschke, M. Möttönen, and J. P. Pekola, Phys. Rev. Lett. 102, 200801 (2009). 

Categories: Talks Monday June 27