Inverse design of artificial two-level systems with Mössbauer nuclei in thin-film cavities

Abstract

Thin-film cavities containing layers of Mössbauer nuclei have been demonstrated to be a rich platform for x-ray quantum optics. At low excitation, these systems can be described by effective few-level schemes, thereby providing tunable artificial quantum systems at hard x-ray energies. With the recent advent of an ab initio theory, a numerically efficient description of these systems is now possible. On this basis, we introduce the inverse design and develop a comprehensive optimization for an archetype system with a single resonant layer, corresponding to an artificial two-level scheme. We discover a number of qualitative insights into x-ray photonic environments for nuclei that will likely impact the design of future x-ray cavities and thereby improve their performance. The presented methods readily generalize beyond the two-level case and thus provide a clear perspective towards the inverse design of more advanced tunable x-ray quantum optical level schemes.

Classical, semi-classical and quantum optical models for x-ray planar cavity with electronic resonance

“…However, there are some limitations of the semiclassical matrix method, for example the formalism will be very complex for the cavity with embedding multiple atomic or nuclear layers [21,66] or double-cavity structure [25], and it is also hard to derive the effective energylevels which is crucial for correlating the experimental spectral observations with physical parameters. Therefore, with the development of the x-ray cavity-QED with the nuclear resonance in last decade, several quantum optical models have been well developed for interpreting and predicting the experimental phenomena, including the phenomenological quantum optical model [67,68] based on the Jaynes-Cummings approach [69], the ab initio few-mode quantum model [70][71][72][73] and the ab initio Green's functions model [70,74,75].…”