Quantum-dot–insulator–superconductor junctions coupled to a microwave resonator*

Quantum dots are finding more and more important applications in the modern electronics. Recent works related to the electron tunneling between a quantum dot and superconducting lead [1,2] inspired us to theoretically study the system consisting of quantum-dot–insulator–superconductor (QIS) junctions coupled to the microwave resonator. For this purpose, we adapted the theory developed before for the so-called quantum-circuit refrigerator [3-6], which is based on normal-metal–insulator–superconductor junctions. We demonstrate that the current running through the QIS junctions can lead to a negative damping rate at the microwave resonator and discuss the possibility to use such a system as a narrow-band amplifier and a microwave laser.
[1] L. E. Bruhat, et al, Phys. Rev. X6,285021014 (2016).
[2] D. van Zanten, et al, Phys. Rev. Lett.116, 166801 (2016).
[3] M. Silveri, et al, Phys. Rev. B96, 094524 (2017).
[4] K. Y. Tan, et al, Nat. Commun.8,15189 (2017).
[5] M. Silveri, et al, Nat. Phys. (2019).
[6] V. A. Sevriuk, et al, Applied Physics Letters115, 082601 (2019).