Nonlinear Exceptional Point Quantum Sensing

Quantum sensing is one of the most promising near-term applications of quantum technologies. While it is known that entanglement between quantum sensors can improve quantum sensors, this can be difficult to achieve in practice. Instead, here we consider whether exceptional points and nonlinearities can be harnessed to improve the sensitivity of a ferrimagnetic oscillator formed from a Yttrium-Iron-Garnet (YIG) magnon resonance with amplified feedback. We will introduce the experimental platform consisting of phase- and amplitude-tunable hopping and show how to realize exceptional points. Then, we show how to incorporate nonlinearities using amplified feedback and demonstrate the generation of frequency combs. We investigate the interplay between exceptional points, frequency combs, and noise to understand whether we can improve the performance of our YIG-based quantum sensor.