Energy and momentum entanglement in parametric downconversion

TL;DR

This paper explains how energy and momentum entanglement in photon pairs generated by parametric downconversion arise from the fundamental indistinguishability of their creation time and position within a nonlinear crystal, offering a simple theoretical treatment.

Contribution

It provides a straightforward theoretical approach to understanding energy and momentum entanglement in parametric downconversion based on indistinguishability principles.

Findings

Entanglement results from indistinguishability of creation time and position.

The treatment simplifies understanding of photon pair entanglement.

Discussion of consequences of system entanglement.

Abstract

We present a simple treatment for the phenomenon of parametric downconversion considering the coherent scattering of one pump photon into a photon pair by a nonlinear crystal. The energy and momentum entanglement of the quantum state of the generated twin photons are seen as a consequence of the fundamental indistinguishability of the time and the position in which the photon pair is created inside the crystal. We also discuss some consequences of the system entanglement.