Two-phonon propagation in a 4-level thermal quantum nanomachine

Acoustic waves, as science of sound, is an established field in physics. In analogy with light, engineers adapt tools from optic fields for manipulating sound waves to fight with cancer cells. Here we present a heat-gradient driven nanomachine concept for simultaneous emission of two phonons, i.e. a convertion of heat into a sonic wave output. Our theoretical work sheds light on nanoscale components or systems that could be used for future ultrasound devices.