CAVITYQPD · Cavity quantum phonon dynamics

Large bodies usually follow the classical equations of motion. Deviations from this can be calledmacroscopic quantum behavior. These phenomena have been experimentally verified with cavity QuantumElectro Dynamics (QED), trapped ions, and superconducting Josephson junction systems. Recently, evidencewas obtained that also moving objects can display such behavior. These objects are micromechanicalresonators (MR), which can measure tens of microns in size and are hence quite macroscopic. The degree offreedom is their vibrations: phonons.I propose experimental research in order to push quantum mechanics closer to the classical world than everbefore. I will try find quantum behavior in the most classical objects, that is, slowly moving bodies. I will useMR's, accessed via electrical resonators. Part of it will be in analogy to the previously studied macroscopicsystems, but with photons replaced by phonons. The experiments are done in a cryogenic temperature mostlyin dilution refrigerator. The work will open up new perspectives on how nature works, and can havetechnological implications.The first basic setup is the coupling of MR to microwave cavity resonators. This is a direct analogy tooptomechanics, and can be called circuit optomechanics. The goals will be phonon state transfer via a cavitybus, construction of squeezed states and of phonon-cavity entanglement. The second setup is to boost theoptomechanical coupling with a Josephson junction system, and reach the single-phonon strong-coupling forthe first time. The third setup is the coupling of MR to a Josephson junction artificial atom. Here we willaccess the MR same way as the motion of a trapped ions is coupled to their internal transitions. In this setup,I am proposing to construct exotic quantum states of motion, and finally entangle and transfer phonons overmm-distance via cavity-coupled qubits. I believe within the project it is possible to perform rudimentary Bellmeasurement with phonons.