Mechanical Gain Enhanced Propagation of Light in a Hybrid Spin‐Mechanical System

Abstract The spin‐mechanical hybrid systems provide a potential platform to reach quantum science and technology, but practical applications with such hybrid quantum systems need the integration of more physical units. In the article, a multi‐mode spin‐mechanical hybrid quantum system is proposed with two‐mode coupling nanomechanical carbon nanotube (CNT) resonators, in which one CNT resonator is loss and the other CNT resonator can be loss, neutral, or gain. The two carbon nanotube (CNT) resonators can interact through a phase‐dependent phonon‐exchange mechanism, which couples them to the same nitrogen vacancy centers in diamond via magnetomechanical effects. By modulating the phase of phonon–phonon coupling and leveraging the Fano‐like resonance phenomenon, double electromagnetically induced transparency can be achieved in this system. This is accompanied by rapid dispersion, resulting in subtle advancements or delays in light propagation. The group index can be manipulated and periodically switched by tuning the modulation phase, with fast‐ and slow‐light effects being particularly pronounced when one CNT resonator is in an active (gain) state compared to lossy or neutral states. This study establishes a foundation for the application of phonon‐mediated optical information storage and processing.