Automated design for quantum forces

Until recently, the development of methods to manipulate light in structures smaller than its wavelength (nanophotonics) relied on 'intuition-based' approaches in which a human designs a device then evaluates its performance. Recently, growth in computational power and new developments in algorithms has led to this process being reversed - a human specifies one or more performance metrics, then a computer is left to design a structure satisfying those goals. This is known as inverse design and is a rapidly expanding field that provides a different kind of insight to techniques found in, for example, machine learning. During this project you will develop and expand upon a version of inverse design that the project's main supervisor recently proposed. The formalism is based entirely on a quantity known as the electromagnetic Green's tensor, which makes it particularly suited to optimise and manipulate the effects that atoms have on each other and those from nearby objects. So far, this formalism has been applied to a process known as resonance energy transfer and another called environment-induced coherence. These two have in common that they can be approximately described as being mediated by light of exactly one frequency. This project aims to extend this technique to take into account multi-frequency effects, particularly for a class of phenomena known as dispersion forces. These are relevant both within physics (e.g. systematic effects in tests of the standard model) and outside (adhesion, stiction, micro/nanomechanical systems). The main difficulty with inverse design of dispersion forces compared to previous applications of the formalism is that they depend on many frequencies simultaneously and are inherently non-additive, so their evaluation is notoriously tricky. The novel methodology used here will be using the new Green's tensor-based inverse design together with cutting-edge programming in Python and Julia to determine the best strategies for optimising dispersion forces and then carry out the relevant simulations. This will allow for the ordinarily tiny effects of dispersion forces to be made more prominent, opening the door for their technological exploitation. The research aligns with the Physical Sciences area of EPSRC's remit, especially with the theme of light-matter interaction and optical phenomena. Some of the longer-term applications of the research might impact the Optical Devices and Subsystems area, via design and modelling of efficient photonic waveguides.