HAPPQP · A hybrid atom-photon-phonon quantum processor

Many quantum information processing tasks were first demonstrated with neutral atoms and ions. With improving capabilities of nanofabrication, a growing number of artificial systems have also shown significant potential in this area and have often even surpassed the early existing systems in their performance and potential for applications.One of these new quantum systems is the optomechanical resonator, consisting of an optical cavity, coupled through the radiation pressure force to a mechanical oscillator. When cooled to the ground state, the mechanical mode can exhibit quantum behavior and be used to process quantum information. Limited by relatively weak photon-phonon coupling, this process is typically probabilistic. In this proposal, we will include a strong non- linearity in order to facilitate a deterministic manipulation of phonons. We will realize this by introducing a single trapped neutral atom, forming a hybrid atom-photon-phonon system. The single atom will be trapped in close proximity to the optomechanical resonator and will strongly couple to the optical mode. As a first demonstration, we will realize a photon blockade effect, which will allow only one photon to enter the cavity at once, prohibiting any multi-phonon generation. This will be verified by a thermal phonon mediated Rabi oscillation experiment. Details of the technique, as well as additional experiments, are discussed in the proposal.The successful completion of these experiments will have a major impact on quantum physics. It represents a milestone towards a fully controllable atom-photon-phonon hybrid quantum system. While the project is ambitious and very competitive, it is just within experimental reach when combining several cutting edge experimental techniques. The experienced researcher Yong Yu is in a unique position to realize this project given his cold atom and quantum optics background, which matches up perfectly with the optomechanics expertise at the host group at TUD.