# Imaging with quantum states of light

## TL;DR

This paper reviews how quantum states of light, especially entangled photons, enable advanced imaging techniques like ghost imaging and resolution enhancement, surpassing classical limits and opening new possibilities in optical imaging.

## Contribution

It provides a comprehensive overview of recent developments in quantum imaging, highlighting novel techniques and their advantages over classical methods.

## Key findings

- Quantum correlations enable ghost imaging with photons that never interact with the object.
- Quantum approaches improve image contrast and resolution beyond classical limits.
- Sub-shot noise phase and amplitude imaging are achievable with quantum states.

## Abstract

The production of pairs of entangled photons simply by focusing a laser beam onto a crystal with a non-linear optical response was used to test quantum mechanics and to open new approaches in imaging. The development of the latter was enabled by the emergence of single photon sensitive cameras able to characterize spatial correlations and high-dimensional entanglement. Thereby new techniques emerged such as the ghost imaging of objects - where the quantum correlations between photons reveal the image from photons that have never interacted with the object - or the imaging with undetected photons by using nonlinear interferometers. Additionally, quantum approaches in imaging can also lead to an improvement in the performance of conventional imaging systems. These improvements can be obtained by means of image contrast, resolution enhancement that exceed the classical limit and acquisition of sub-shot noise phase or amplitude images. In this review we discuss the application of quantum states of light for advanced imaging techniques.