Excited to excited state scattering using weak measurements

TL;DR

This paper theoretically demonstrates that weak value amplification can occur in elastic resonance fluorescence from atomic excited states, revealing new insights into system-bath interactions and matching experimental observations.

Contribution

It introduces a theoretical framework showing weak value amplification in atomic resonance fluorescence, extending understanding of quantum measurement effects in system-bath interactions.

Findings

Weak interaction regime identified in resonance fluorescence

Amplification of mean scattering time observed for specific states

Theory reproduces experimental results and predicts scattering timescales

Abstract

Weak measurements are a subset of measurement processes in quantum mechanics wherein the system which is being measured interacts very weakly with the measuring apparatus. Measurement values of observables undergoing a weak interaction and their amplification, are concepts that have sharpened our understanding of interaction processes in quantum mechanics. Recent experiments show that naturally occurring processes such as resonance fluorescence from excited states of an atom can exhibit weak value amplification effect. In this paper, we theoretically analyze the process of elastic resonance fluorescence from a V-type three level atomic system, using the well known Weiskopff-Wigner (W-W) theory of spontaneous emission. Within this theory, we show that, a weak interaction regime can be identified and for suitable choices of initial and final excited states, the mean scattering time between these states show an amplification effect during interaction with the vacuum bath modes of the electromagnetic field. We thus show for the first time that a system bath interaction can show weak value amplification. Using our theory we reproduce the published experimental results carried out in such a system. More importantly, our theory can calculate scattering timescales in elastic resonance scattering between multiple excited states of a single atom or between common excited state configurations of interacting multi-atom systems.