Entanglement between very different entities such as traveling sound waves, phonons, and optical photons

https://www.eurekalert.org/news-releases/1064880

"efficient, based on Brillouin-Mandelstam scattering optical nonlinear effect... coupling at different energy scales, phonons moving at  much slower speed....can operate at temperatures in the tens of Kelvin. This is much higher than those required by standard approaches, which often employ expensive equipment such as dilution fridges... alternative to volatile photons, for quantum memory, quantum repeaters/ signal processing... possibility of implementing this concept in optical fibers or photonic integrated chips"