Join for the emerging field of opto-mechanics and the highest Qxf product of any micromachined mechanical resonators to date! Topic: Ultrahigh Q mechanical resonators for quantum cavity optomechanics Speaker: Yeghishe Tsaturyan Time: Monday, 20 November 2017, 11:00 – 12:00 PM Location: PHYS 242 Over the past decade the field of cavity optomechanics has experienced remarkable progress and has emerged as a strong candidate for future quantum technologies. This progress has heavily relied on the ongoing experimental and theoretical studies of dissipation in micro- and nano-mechanical resonators. Most notably, stressed silicon nitride (SiN) resonators have generated a tremendous amount of interest and a large number of researchers in the nano- and optomechanics communities have devoted their time to study and perfect mechanical resonators based on stressed SiN thin films. In this talk I will present a novel approach to significantly improve the performance of SiN membrane resonators, suppressing radiation-, as well as intrinsic mechanical losses. This is achieved by localisation of vibrations by means of phononic crystal patterning of a stressed SiN membrane, which ultimately leads to a reduced curvature in the displacement field of the membrane and thus reduced losses due to bending. This “soft clamping” approach enables realisation of mechanical resonators with a Qf-product of (1.66 ± 0.02) ×10^14 Hz at room temperature, which is the highest reported value of any microfabricated mechanical resonator to date. Finally, I will present recent work in quantum cavity optomechanics conducted at the Niels Bohr Institute involving soft clamped resonators. These results pave the way for long-coherence quantum optical experiments involving macroscopic mechanical resonators. Best, Pen-Li (Ben) Yu, PhD Postdoctoral research associate Purdue University 765-496-2073<tel:(765)%20496-2073>