The next CU Phonon Club seminar of the semester will be held on 3/22. Please join us for a great talk, interesting discussion, and FREE FOOD! Hope to see you there! Additionally, if anyone is interested in being involved in the organization of CU Phonon Club, please email: email@example.com.
Quantum memories play a critical role in quantum information processing (QIP), facilitating the storage and retrieval of quantum information for on-chip and long-distance quantum communications, with diverse applications ranging from aerospace to medical imaging. It is now well established that quantized vibrations (phonons) in mechanical oscillators can behave quantum mechanically under specific conditions and can play an important role in QIP. Bulk acoustic wave (BAW) phonons, which vibrate within the bulk of a material, are promising candidates for storing quantum information due to their long lifetimes. In this work, we investigate a hybrid photon-magnon-phonon system, where BAW phonons are excited in a Gadolinium Iron Garnet (GGG) thick film by quantized electron spin-waves (magnons) in a Yttrium Iron Garnet (YIG) thin film and are coupled to microwave photons. Recent experiments on a millimeter scale YIG/GGG device at room temperature show that the memories are limited by the phonon lifetime of 0.2 μs. It is expected that operating in the milliKelvin regime will allow the memories to have a higher phonon lifetime, limited by diffraction, which is less understood. We present theoretical and numerical analysis to predict the diffraction-limited BAW phonon lifetime limits, mode shapes, and their coupling strengths to magnons. We further analyze the effects of magnon-phonon coupling and phonon lifetimes on the dynamics of the hybrid system using Heisenberg-Langevin equations and discuss their experimental implications.