HYSPECQS · Hybrid spin-mechanical quantum systems

In the last years the field of optomechanics, which studies the interaction of light with mechanical oscillators, has advanced considerably. Many pioneering experiments have demonstrated the ability to achieve quantum control of meso- and macroscopic systems. However, the intrinsic Gaussian nature of optomechanical systems makes the creation of complex non-classical states of motion challenging. In order to access them a quantum non-linearity, such as an electronic spin, needs to be introduced. Achieving strong coupling between a spin and a mesoscopic mechanical oscillator would have far-reaching implications, from tests of the foundations of quantum mechanics to applications in sensing and quantum information. Despite several attempts, this regime has remained elusive so far because of limitations such as short coherence times or low spin-mechanical coupling rates. In HYSPECQS I will overcome the limitations on coupling rate and coherence time by using state-of-the-art platforms. The spin degree of freedom will be provided by nitrogen-vacancy defects in diamond, which can display hundreds of microseconds-long coherence times. The mechanical resonators, pioneered by the host group, are embedded in a thin silicon nitride membrane patterned with a phononic crystal. These resonators have been demonstrated to reach seconds-long coherence times at few tens of millikelvins. By functionalizing the resonators with nanoparticles generating high magnet field gradients, I will achieve strong spin-mechanical coupling, I will demonstrate sub-ms spin state detection with a mechanical resonator, and I will generate non-classical states of motion. The project will be carried out in the group of Prof. Albert Schliesser at the Niels Bohr Institute, Copenhagen. I will gain theoretical and experimental understanding of cavity quantum optomechanics, which will complement my existing expertise on spin physics and interferometry, thereby enhancing my scientific and professional profile.