Theory seminar
Electromagnetic Properties of a Wire Medium Slab
Speaker: Adam Kicman (Y4)
Date: Wednesday 22 May 2024
Time: 15:00
Venue: N/3.28
Wire media are an artificially designed material, i.e. meta-material, composed of an array of wires assembled in a rectangular grid. Their photonic dispersion depends on the wave-vector as well as frequency, which complicates their interactions with electromagnetic waves. It becomes particularly noteworthy when investigating the transmission and reflection coefficients of such wire media. An approach put forward in the literature suggests the need to include additional boundary conditions when solving Maxwell's equations, from which the transmission and reflection coefficients can be obtained. In this project, an alternative formalism was proposed, independent of additional boundary conditions, which instead exploits the geometry of the wire medium to obtain the transmission and reflection coefficients. This approach was used to successfully obtain both an analytical expression and numerical results for these coefficients. Speaker: Angelos Seizas (Y4) Title: Quantum criticality in single-emitter light-matter systems Abstract: It has been shown that the quantum Rabi model and the Jaynes-Cummings model - two paradigmatic models in quantum optics - have the ability to exhibit critical behaviour at sufficiently low or zero temperature, termed superradiant phase transition, despite lacking spatial structure and being composed of only a single two-level emitter and a single bosonic mode, where the thermodynamic limit is not applicable. Given the fact that these deceptively simple models display rich physics that is highly relevant to contemporary research, this talk will explore and compare a number of ways in which their critical behaviour is shown to manifest and will furthermore discuss whether this behaviour signifies a genuine quantum phase transition or if a conceptual re-evaluation of phase transitions is needed.