T-Recs · Tunable and Reconfigurable Nanoacoustics

In solid-state physics, all the properties determined by the atoms' position are susceptible to be modified by acoustic phonons. Acoustic phonons are usually seen as a primary source of unwanted effects in electronics, optoelectronics, and quantum technologies based on solid-state platforms. This project proposes a series of tunable nanodevices where acoustic-phonons constitute, instead, a central resource to unveil wavelength conversion phenomena, transfer information, and simulate systems difficult or impossible to study in optics and electronics. The current trend in nanophononics is to engineer acoustic nanodevices to shape the local acoustic density of states, tailor the light-matter interaction, or enhance the interactions with other systems based on static and predetermined fixed-function nanostructures. This project takes a radically different direction by incorporating responsive materials that change their elastic properties under external stimuli. GeSbTe compounds and vanadium dioxide present phase transitions that can be triggered thermally, optically, or electrically and have associated ultrafast changes in their elastic properties. These materials, widely used in active photonics and electronics, will be integrated into nanophononic semiconductor and oxide-based resonators working in the GHz-THz range.The project is organized around three major challenges: i) To develop hybrid tunable acoustic-phonon resonators and transducers based on materials presenting structural phase transitions. ii) To develop reconfigurable nanophononic lattices (i.e. artificial graphene) formed by coupled resonators. And iii) To demonstrate novel acoustic-phonon wavelength conversion phenomena, simulate time-dependent Hamiltonians, and develop dynamical acoustic phonon devices. Using dynamical structures to control acoustic phonons in the GHz-THz range will enable a new dimension in the solid-state physics toolbox.