# Quantum phase-sensitive diffraction and imaging using entangled photons

## TL;DR

This paper introduces a quantum diffraction imaging method using entangled photons, enabling phase-sensitive imaging with low light levels to protect delicate samples, and proposes a Schmidt mode-based image enhancement technique.

## Contribution

It presents a novel quantum diffraction imaging technique utilizing entangled photons and demonstrates phase-sensitive imaging with reduced light intensity, avoiding sample damage.

## Key findings

- Imaging signal scales as √I_p, allowing weak-field imaging.
- Phase information is imprinted in the entangled photon state.
- Schmidt decomposition can enhance image quality.

## Abstract

We propose a novel quantum diffraction imaging technique whereby one photon of an entangled pair is diffracted off a sample and detected in coincidence with its twin. The image is obtained by scanning the photon that did not interact with matter. We show that when a dynamical quantum system interacts with an external field, the phase information is imprinted in the state of the field in a detectable way. The contribution to the signal from photons that interact with the sample scales as $\propto I_{p}^{1/2}$, where $I_{p}$ is the source intensity, compared to $\propto I_{p}$ of classical diffraction. This makes imaging with weak-field possible, avoiding damage to delicate samples. A Schmidt decomposition of the state of the field can be used for image enhancement by reweighting the Schmidt modes contributions.