Phys.org February 14, 2023
Plasmon modes are treated as quasiparticles, and they are considered essential for the realization of future nanoscale quantum functionality. Implementing and demonstrating such functionality requires access to the quasiparticle’s quantum state to monitor and manipulate its corresponding quantum wave packet dynamics in Hilbert space. Researchers in Germany succeeded in detecting such superposition states of light directly in a nanostructure using plasmon-assisted electron emission as a signal in coherent two-dimensional nanoscopy. The observation of a quantum coherence oscillating at the third harmonic of the plasmon frequency was traced back to the superposition of energetically non-adjacent plasmon occupation number states and was therefore a direct fingerprint of the quantum wave packet. The team has demonstrated the existence of a plasmon quantum wave packet via the coherence between certain occupation number states and provided an improved model for plasmon-assisted electron emission processes. According to the researchers their results may enable time-dependent probing and manipulation of coupled quantum states and dynamics on the nanoscale… read. TECHNICAL ARTICLE
Comparison of measured and simulated rephasing 2D spectra… Credit: Nature Physics (2023)Â