We explore applications of nonlinear circuit QED with a charge qubit inductively coupled to a microwave LC resonator in the photonic engineering and ultrastrong-coupling multiphoton quantum optics. Simply sweeping the gate-voltage bias achieves arbitrary Fock-state pulsed maser, where the single qubit plays the role of artificial gain medium. Resonantly pumping the parametric qubit-resonator interface leads to the squeezing of resonator field, which is utilizable to the quantum-limited microwave amplification. Moreover, upwards and downwards multiphoton quantum jumps may be observed in the steady state of the driving-free system.
@article{arxiv.1809.06542,
title = {Charge-Qubit-Resonator-Interface-Based Nonlinear Circuit QED},
author = {Deshui Yu and Leong Chuan Kwek and Luigi Amico and Rainer Dumke},
journal= {arXiv preprint arXiv:1809.06542},
year = {2018}
}