Near-field-driven thermal phonon lasing.

The extreme electromagnetic near-field environment of nanoplasmonic resonators and metamaterials can give rise to unprecedented electromagnetic heating effects, enabling large and manipulable temperature gradients on the order of 10-10 K/nm. In this Letter, by interfacing traditional semiconductor quantum dots with industry-grade plasmonic transducer technology, we demonstrate that the near-field-induced thermal gradient can facilitate the requisite population inversion for coherent phonon amplification and lasing at the nanoscale. Our detailed analysis uncovers both the characteristics and parameter sensitivity of inversion and relaxation oscillations in the system, thereby unveiling hitherto unexplored opportunities for leveraging plasmonic near-field effects in the context of quantum thermodynamics and phononics.