Quantum enhanced multi-parameter estimation

Researchers have applied Fisher information to quantify the precision in estimating single parameters such as absorption or phase in simple optical systems and to report instances where quantum strategies can perform beyond the classical limit. Recently, the field has grown to explore how to perform multi-parameter estimation beyond the classical limit. Key to this quantum metrology has been identifying the classical precision limit in parameter estimation - after all, you need to define a limit in order to surpass it. The motivation behind this PhD project will be to explore if this classical limit is always appropriate and explore what a classical limit in resources means from a sensing perspective. We will strive to better define the classes of measurement that correspond to each, relevant, defined classical limit for realistic imaging and sensing scenarios, inspired by complexity classes that group together different computational resources according to the quantified resources required.