Theoretical Physics Seminar: Sofia Qvarfort (UCL)

Measuring gravitational acceleration and entanglement with optomechanical systems

Abstract: Optomechanical systems, being some of the largest quantum-mechanical systems that we can control in the lab, show excellent potential for probing gravitational effects at low energies. In my talk, I will outline two different theoretical applications of optomechanical systems in this context. Firstly, I will show how a nonlinear cavity optomechanical system can be used for measurements of gravitational acceleration g, also known as gravimetry. I will review tools such as the Fisher information and use them to derive a fundamental sensitivity for measurements of g. We find, among other things, that the phase of the optical output encodes the gravitational acceleration g, and that it can be optimally measured with a homodyne measurement. Secondly, I will show how entanglement from a central-potential interaction between two levitated nanospheres (including Newton’s gravitational potential) can be modelled for a scheme using Gaussian states. We find that, unsurprisingly, gravitational entanglement will not be readily detectable within this scheme, but that entanglement due to the Casimir potential should be experimentally accessible with current experiments.

 

Paper references:

https://www.nature.com/articles/s41467-018-06037-z

https://arxiv.org/abs/1812.09776