The armchair quantum physicist

Quantifying Einstein’s ‘Spooky action at a distance’

Entanglement is the most enigmatic phenomenon of quantum theory. It is also what creates the most striking differences between quantum mechanics and classical theories. Entanglement describes the correlation between events at different locations and is often in conflict with our intuition. In 2022, the Nobel Prize was awarded to the team of scientists who experimentally…
Quantum teleportation with FockStateCircuit

In this post we dive in to quantum teleportation and follows the trails of the pioneers who invented and first realized teleportation. We look at the original articles and replicate the experiments in Python code. Teleportation is about bringing an intact quantum state from one place to the other. It is key tool in quantum…
Simulation of Greenbergen-Horne-Zeilinger entanglement creation

We replicate (in Python) the experiment from the group of Anton Zeilinger in 1999 where for the first time entanglement between more than two photons was demonstrated in a so-called GHZ state.
EPR Paradox and Bell inequality: Is the world real?

We look at the history of the discussion triggered by Einstein in his famous EPR paper. We encounter different versions of Bell’s inequality. Finally we show how we can simply simulate the experiments from Alain Aspect in the 80’s in which the fact that quantum theory violates Bell’s inequality was first demonstrated.
Building quantum optical systems in Python

In Python the module ‘FockStateCircuit’ can model (quantum) optical quantum circuits with well-defined numbers of photons ( 0,1,2,3, …photons per channel). With ‘FockStateCircuits’ we can model optical components, like beamsplitters or waveplates. Circuits can also contain classical channels to store measurement results. It is easy to replicate famous experiments like Alain Aspects Nobel Prize winning…
Simulating the HOM effect on a quantum computer

In this post we simulate a quantum effect on a real quantum computer. The effect is the quantum HOM effect observed on beamsplitters. Due to quantum interference photons ‘bunch’ together rather than going their individual ways. In this post we show how to simulate this on quantum computer. When we run the algorithm on a…
The HOM effect explained

In this post we explore the HOM effect and describe it by simple mathematics. We will see that we are looking at ‘quantum interference’ where the system can take different ‘paths’ to get to the same outcome. In quantum theory these paths can ‘interfere’, leading to the results we observe.
Beamsplitters and the quantum HOM effect

In this notebook we use a very simple optical component: A beamsplitter. We will see in this simple component already very interesting quantum behavior like the quantum HOM effect (named after Hong, Ou and Mandel who first reported this effect).
Greenberger-Horne-Zeilinger entanglement

We use Python Qutip to model the setup which was used by Anton Zeilinger and co-workers to create and demonstrate entanglement between three spatially separated photons.
Experimental test of Bell’s inequality

We use Python Qutip to replicate the experiment performed by Alain Aspect and co-workers in 1982, where for the first time the violation of Bell’s inequalies was experimentally demonstrated.