Time-varying Mie resonators for real-time manipulation of quantum emitter radiation

Quantum emitters are fundamental to advancing technologies such as secure quantum communication, high-resolution imaging, and quantum computing by enabling on-demand single-photon generation. Precise control over the spectral and radiation characteristics of quantum emitters is crucial for optimizing quantum devices and integrated photonic systems. Nevertheless, traditional designs based on passive materials impose fixed functionality postfabrication, limiting the ability to tune spontaneous emission dynamically. This study introduces time-varying Mie resonators as a dynamic means to achieve real-time control over the spontaneous emission of a quantum source. A theoretical framework combining the time-Floquet method with multipole expansion is developed to model light-matter interactions in time-modulated environments. Our findings reveal that time modulation enables precise control over multipolar resonant modes, compensating for frequency detuning in the quantum emitter's radiation through an optimal feedback strategy. Moreover, we demonstrate that time modulation can facilitate directional control of far-field emission by selectively exciting specific multipoles and manipulating their mutual coupling. We further show that transverse Kerker conditions enhance radiation directionality and that time modulation can convert nonradiating anapole states into radiating modes via symmetry breaking. Our findings provide a comprehensive framework for real-time manipulation of quantum emitter radiation and open up possibilities for unique applications in integrated quantum physics.