Abstract: Quantum sensors such as spin defects in diamond have achieved excellent performance by combining high sensitivity with spatial resolution. Unfortunately, these sensors can only detect signal fields with frequency in a few accessible ranges (a narrow window around the sensors’ resonance frequency), and extracting vectorial information usually satisfies the sensor's nanoscale spatial resolution. In this talk, I will introduce our recent work on sensing arbitrary-frequency vector signals by using the sensor qubit as a quantum frequency mixer. The technique leverages nonlinear effects in periodically driven (Floquet) quantum systems to achieve quantum frequency mixing of the signal and an applied bias ac field. The frequency-mixed field can be detected using well-developed sensing techniques such as Rabi and CPMG. In addition to enhancing the sensing performance by mediating spin transitions, the synthetic Floquet energy levels can improve the capabilities of quantum simulators, which is reported in another of our work. By implementing modulated driving and performing projective measurements (generalized Rabi oscillation), we can engineer and characterize dynamical symmetries in time domain. In summary, our contributions pave the way for building more powerful quantum sensors and simulating more interesting phases.

References:[1] https://journals.aps.org/prx/abstract/10.1103/PhysRevX.12.021061[2] https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.127.140604[3] https://pubs.acs.org/doi/10.1021/acs.nanolett.1c01165[4] https://arxiv.org/abs/2205.02790