Modulator-Assisted Zeno Control of Energy Transfer in Quantum Batteries

Efficient operation of quantum batteries requires not only fast energy transfer but also the ability to halt the charging process to prevent reverse flow. Existing approaches typically rely on direct control of the charger-battery interaction, which can be experimentally demanding. Here we propose a modulator-assisted quantum battery protocol that enables indirect control of energy transfer while keeping the interaction always on. By applying repeated local unitary operations to an auxiliary modulator qubit, we exploit a Zeno-like mechanism to dynamically reshape the effective Hamiltonian and switch the charger-battery coupling on and off. We demonstrate this mechanism in a minimal three-body model and show that it remains effective beyond the ideal fast-control limit. We further extend the protocol to a collective many-body architecture, where it preserves the characteristic enhancement of charging power, scaling as $N^{3/2}$ with the number of battery units. Our results establish modulator-assisted Zeno control as a scalable route to regulating energy transfer in quantum batteries, and we further discuss a possible implementation in an NV-$\Cs$ spin platform.