Space-time duality in polariton dynamics

TL;DR

This paper explores the space-time duality in polariton dynamics, demonstrating control over their propagation through temporal shaping of excitation and validating the model with terahertz near-field measurements.

Contribution

It introduces a method to manipulate polariton propagation in space and time via temporal waveform engineering, supported by experimental visualization and modeling.

Findings

Suppressed spatial decay achieved by waveform shaping

Experimental data aligns with the dynamic model

Space-time duality observed in polariton behavior

Abstract

The spatial and temporal dynamics of wave propagation are intertwined. A common manifestation of this duality emerges in the spatial and temporal decay of waves as they propagate through a lossy medium. A complete description of the non-Hermitian wave dynamics in such a lossy system, capturing temporal and spatial decays, necessitates the use of complex-valued frequency and/or wavenumber Eigen-values. Here, we demonstrate that the propagation of polaritons - hybrid light-matter quasiparticles - can be broadly controlled in space and time by temporally shaping their photonic excitation. Using time-domain terahertz near-field nanoscopy, we study plasmon polaritons in bilayer graphene at sub-picosecond time scales. Suppressed spatial decay of polaritons is implemented by temporally engineering the excitation waveform. Polaritonic space-time metrology data agree with our dynamic model. Through the experimental realization and visualization of polaritonic space-time duality, we uncover the effects of the spatio-temporal engineering of wave dynamics; these are applicable to acoustic, photonic, plasmonic, and electronic systems.