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Updated: Dec 7, 2025

A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference

A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference

Published on: September 5, 2019

Path identity as a source of high-dimensional entanglement.

Jaroslav Kysela^1,2, Manuel Erhard^1,2, Armin Hochrainer^3,2

¹Faculty of Physics, Vienna Center for Quantum Science & Technology, University of Vienna, 1090 Vienna, Austria; anton.zeilinger@univie.ac.at jaroslav.kysela@univie.ac.at manuel.erhard@univie.ac.at.

Proceedings of the National Academy of Sciences of the United States of America

|October 2, 2020

Summary

We demonstrate a new quantum entanglement framework, "entanglement by path identity," enabling customizable, high-dimensional entangled photon pairs. This approach is versatile for future quantum technologies and fundamental physics experiments.

Keywords:

entanglement by path identity high-dimensional entanglement orbital angular momentum path indistinguishability

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Area of Science:

Quantum Information Science
Quantum Optics
Quantum Entanglement

Background:

Quantum entanglement is crucial for quantum technologies, but generating specific entangled states can be challenging.
Existing methods often tie entanglement properties to the physical generation process.

Purpose of the Study:

To experimentally demonstrate a general entanglement generation framework independent of the physical process.
To introduce and utilize the 'entanglement by path identity' framework for customizable quantum states.
To develop a modular source for high-dimensionally entangled photon pairs.

Main Methods:

Utilizing indistinguishability of generation processes and setup geometry to create entanglement.
Employing specific geometries within the 'entanglement by path identity' framework.
Building a modular photon pair source to generate high-dimensional entanglement in orbital angular momentum.

Main Results:

Demonstrated creation of three-dimensionally entangled states using the new framework.
Showcased incremental increase in entanglement dimensionality while maintaining state quality.
Developed a modular source adaptable to various degrees of freedom and integrated devices.

Conclusions:

The 'entanglement by path identity' framework offers a customizable and general approach to generating quantum entanglement.
The modular source design facilitates the creation of high-quality, high-dimensional entangled states.
This approach is expected to benefit future quantum technologies and fundamental tests in higher dimensions.