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Source of polarization entangled photon pairs ready for violation of Bell’s inequality.

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Quantum mechanics is deeply rooted in the heart of modern physics. But it is not easy to teach. Quantum theory often contradicts our everyday life experience and the corresponding experiments are neither easy to setup nor to maintain.

When Aspect, Roger and Dalibard showed that entangled photons violate Bell’s inequality for the first time in 1982, their setup filled the whole basement lab. The quED fits on any lab desk and can be set up in minutes. And it is more accurate and a lot more efficient than the apparatus of Aspect and his colleagues.

qutools’ Entanglement Demonstrator is designed for educational purposes. The easy-to-use system frees the hands and brains of anyone trying to explain the complex phenomena of quantum mechanics. Because that’s already hard enough.

quED: “Spooky action at a distance”? Not so spooky anymore…

Sample Experiments

With add-ons (optional):


The functionality of the quED system can easily be extended with three add-ons:

+ quED-MI
Michelson Interferometer
Demonstrate the wave nature of single photons through their interference or build a quantum eraser.

+ quED-HBT
Hanbury Brown Twiss Add-On
Perform the “Grangier Experiment”, explore the particle nature of single photons with a Hanbury Brown & Twiss setup and build a quantum random bit generator.

+ quED-HOM
Hong–Ou–Mandel Effect
Experience the purely quantum 2-photon interference effect by revealing the Hong-Ou-Mandel dip.

Key Features

  • Hands-on study of quantum entanglement
  • Compact design, user-friendly operation
  • Complete system: Ready to violate Bell’s inequalities
  • High performance: Entanglement verification in only a few seconds
  • Optional: Custom configuration that is ideally suited for specific applications

qutools’ Entanglement Demonstrator is designed with educators in mind. It’s the easiest and most reliable way to explain the complex phenomena of quantum mechanics by generating and analysing polarization-entangled photon pairs.

It’s a science project kit for modern physics.

Its design combines recent achievements of quantum optics technology into an easy-to-use system for academic, research and applied purposes with precise accuracy. Advanced models for scientific purposes are available as well, with a high performance meeting the requirements of state-of-the-art physics experiments.


  • Student lab course experiments, for example:
  • Preparation/ analysis of distinct entangled states, violation of Bell’s inequalities
  • Quantum state tomography
  • Single photon experiments (e.g. single photon interference, quantum eraser)
  • Two-photon interference (Hong-Ou-Mandel) experiment with add-on qu2PI

System Includes

  • Source of fiber-coupled polarization-entangled photon pairs
  • Two silicon photodiode avalanche detectors
  • Alignment help utilities including auxiliary low-power laser module
  • Three-channel counter with integrated coincidence logic unit
  • Control and read-out unit


George Musser, editor at Scientific American magazine and the author “Spooky Action at a Distance” and “The Complete Idiot’s Guide to String Theory” about the quED: “Do-it-yourself quantum spooky action! An experiment that used to fill a basement lab now fits on any table.”

Dr. Eleni Diamanti, Université Pierre et Marie Curie, Paris: “We use the quED in my laboratory as a central element for our teaching activities; it is always a great and guaranteed success thanks to its stability and reliability. We have also extensivley used it in experiments ranging from the demonstration of nonlocal quantum games (Phys. Rev. Lett. 2015) to the reference-frame-independent quantification of bipartire entanglement (Phys. Rev. A 2014), more experiments are underway. “

Dr. Ulrich Busk Hoff, Danmarks Tekniske Universitet: “At DTU Physics we are proud to have high-quality products from qutools which allow us to do engaging outreach and hands-on teaching of fundamental quantum physics. The quED is an impressive product that puts everyone in a position to experiment with quantum physics. Thanks to our setups from qutools, Bell’s inequality has finally been violated for the first time in Denmark.”

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