Within the emerging field of Quantum Optomechanics, it has become possible in recent years to establish a quantum interface between light and the motion of an engineered mechanical oscillator, and to observe such effects as motional sideband asymmetry, radiation pressure shot noise, and ponderomotive squeezing. These achievements are now being extended towards applications and fundamental research. The possibility to manipulate motion at the quantum level opens new avenues such as sensing technologies with unprecedented sensitivities, encoding quantum information in ultrahigh-quality nanomechanical systems, and engineering macroscopic quantum states for testing of fundamental quantum physics. I will describe my recent work with optomechanical photonic crystals, demonstrating quantum measurement techniques that evade quantum backaction noise [1,2] and enable sensing of force and displacement beyond the standard quantum limit. I will also report on laser cooling of macrosopic mechanical motion down to a record level of 92% ground state occupation . I will show how to extend these results with related methods to generate mechanical squeezed states. Finally, I will describe my recent theoretical proposal for generating superposition (cat) states in a macroscopic oscillator , that directly builds upon these techniques.
 Shomroni et al., Phys. Rev. X 9, 041022 (2019)
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 Qiu*, Shomroni* et al., Phys. Rev. A 100, 053852 (2019)
 Qiu*, Shomroni* et al., arXiv:1903.10242
 Shomroni et al., arXiv:1909.10624