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Part of: A Science Kit for Quantum Physics.

  • Setup of the manual 2-photon tomography with the quED.

  • Overview
  • Sample Experiments
  • Add-Ons
  • System Includes
  • Variants
  • Downloads


The quED-TOM let you determine the full quantum state density matrix that defines all properties of either a single photonic qubit or even the two-qubit entangled or non-entangled state that can be produced in the quED source.

It basically consists of two additional quarter wave plates and an easy-to-use software with which you can record the data for an overcomplete tomography scheme.

Like most of the other AddOns, the quED-TOM can be manual or motorized. You can use the software as data collection and analysis also with the manual version, whereas in the motorized version, the experiments can be run fully automated.

Sample Experiments

Here is a list of the experiments where the quED-TOM is involved.

Single Photon Experiments with Interference

These are the experiments we have come up with so far and found interesting enough to put them here. Do you have more ideas? Please let us know!

Other Add-Ons

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

+ quED-MI Michelson Interferometer

Demonstrate the wave nature of single photons through their interference or build a quantum eraser.

Single Photon Michelson Interferometer Add-On for the quED.

  • Single Photon Michelson Interferometer Add-On for the quED.

Interference is generally considered to be a wave phenomenon. Curiously it also works with single quantum objects. Use the quED-MI Michelson Interferometer add-on together with the quED to show that this is the case. (The photograph shows the motorised version.)

Read more about the quED-MI Michelson Interferometer.

+ 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.

Hanbury Brown & Twiss Setup for Heralded Single Photon Sources.

  • Hanbury Brown-Twiss setup Add-On for the quED

Photons (or generally quantum objects) sometimes also behave like particles. With this add-on you can show that photons can not be split up. You can also explore a simple quantum random bit/number generator and use it in combination with the quED-MI to show wave and particle nature of photons in one experiment.

Read more about the quED-HBT.

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

Hong-Ou-Mandel Interferometer Demonstrating 2-Photon Interference.

  • Hong-Ou-Mandel effect Add-On for the quED

When you have two indistinguishable photons and each of them hit one input of a beam splitter, they exit the beam splitter together in one output port. This is an effect you cannot demonstrate with bright light, but with this add-on you can.

Read more about the quED-HOM.

+ quED-QKD Quantum Cryptography

Securely distribute a secret key between Alice and Bob with the BB84 protocol.

Quantum Cryptography Add-On for the quED.

One of the most popular industrial applications for quantum phenomena right now is quantum cryptography, or better, quantum key distribution. With this add-on, you can use weak coherent pulses to simulate realistically how a secure communication between two parties (Alice and Bob) is made possible by the BB84 protocol in a real environment.

Read more about the quED-QKD.

System Includes

The quED-TOM is an add-on to the quED and consists of the following parts:

  • 2 additional quarter wave plates
  • easy-to-use software for recording the data for an overcomplete tomography


There are two variants of the quED-TOM:

  • Manual: Ideal for student lab courses, where the students are supposed to perform the measurements themselves.
  • Motorized: Intended for demonstrations during lectures or at science exhibitions, classes and research, when the result matters more than the process of measuring.


quED-TOM manual 07/2022 4.5 MB pdf
quED-TOM sample solution 10/2021 1.8 MB pdf