# Optical attenuation without absorption

## TL;DR

This paper demonstrates that by post-selecting non-transitional atomic states, one can achieve optical attenuation exceeding normal absorption and even induce amplification, revealing novel quantum control of light-matter interactions.

## Contribution

It introduces a method of optical attenuation and amplification based on post-selection in a two-level atomic ensemble, surpassing traditional absorption effects.

## Key findings

- Post-selection can enhance optical attenuation beyond normal absorption.
- The process can produce optical amplification under strong photon-atom interactions.
- The method offers new quantum control techniques for light propagation.

## Abstract

We consider a coherent state of light propagating through an ensemble of two-level atoms where all the atoms are initially in their ground state. In ordinary absorption, the transition of atoms to their excited state along with the absorption of a photon will remove energy from the beam and attenuate the signal. Here we show that post-selecting on those cases in which none of the atoms made a transition to the excited state can give even more attenuation than would normally occur due to absorption. The same process can also produce amplification when there is a sufficiently strong interaction between the photons and the atoms.

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Source: https://tomesphere.com/paper/1903.02041