Qoffee Maker

Build a quantum circuit, measure it, and get the drink the measurement chose. Each beverage is a bit pattern — 000, 001, 010 … — so ordering a cappuccino means constructing a circuit whose measurement lands on the right one. Quantum mechanics being what it is, you can shift the odds but never quite give an order.

Needs: a display · a network connection · Start it with: rq_demo_run.sh qoffee-maker

Run it

Double-click the Qoffee Maker icon on the desktop. It starts the Qoffee container, opens qoffee.ipynb, and switches straight into the app view — you do not have to run any cells yourself.

It is also under Applications → RasQberry → Qoffee Maker, or in sudo raspi-config → 0 RasQberry → Quantum Computing Demos.

The first launch pulls the Qoffee container image, so give it a few minutes and a decent connection. After that it starts quickly.

If you end up looking at the notebook instead of the app — the auto-start did not take, or you opened qoffee.ipynb yourself — click the rocket icon (🚀) in the toolbar. That runs every cell and starts the app view, which is exactly what the icon does for you.

What you'll see

Drag gates onto the qubits to build a circuit. The interface shows the probability of each of the eight outcomes, and which drink each one pours. Choose a backend to compare an ideal simulation against one with realistic noise — the noisy run is the honest one, and it is a good way to feel what error means in practice before anyone mentions error correction.

Start by aiming for an outcome you can hit reliably (000, or 111), then try for a specific drink in the middle. That is where it gets interesting: superposition means your circuit sets probabilities, so you may need a few attempts — which is the point of the demo.

With a real Home Connect coffee machine attached, the winning measurement actually brews it. Without one, everything works except the coffee.

Credits and documentation

By Max Simon and Jan-R. Lahmann, from the "serious games for quantum computing" family. Full details, the hardware setup and the event kit are on the project's own site:

• qoffee-maker.org — the project and its documentation
• Fun with Quantum — more quantum games, also on this image
• IBM Quantum Learning: measurement

See the Demo List for everything else on the image.