Quantum Computer Mini Zone

This project was created for the Rextro 2025 exhibition, held at the University of Ruhuna, Faculty of Engineering, based on an idea by Dr. Thilina Weerasinghe and developed under the guidance of Dr. Kaveen Liyanage.

Rextro is one of the largest exhibitions in Sri Lanka, drawing more than 15,000 visitors, most of them members of the general public and school students. Our objective was to give every visitor a genuine, intuitive understanding of how a quantum computer actually works — and we succeeded. This was not an easy task, since several of the underlying concepts are difficult to grasp even for people with a technical background.

We quickly realized that a single exhibit would not be enough to explain something this layered, so we expanded the project into a full “Mini Quantum Computing Zone.” We designed six exhibits, arranged so that a visitor moving through them in sequence would build a genuine understanding of quantum computing by the end of the walk-through:

1. Steel Dome
2. Qubit Superposition
3. Double-Slit & Single-Slit Experiments
4. Bloch Sphere & Quantum Gates
5. Entanglement
6. Quantum Computer Model Demo

Visitors started at exhibit one and finished at exhibit six. Let’s walk through what each one was designed to teach.

1. Steel Dome

We wanted the Mini Quantum Zone to be as engaging as possible, both to draw more visitors in and to spark genuine curiosity — enough, hopefully, that a few of them might go on to build a real interest in the field. That ambition is the main reason we built a steel dome at all, even though it was time-consuming and, admittedly, a bit beyond our original scope.

The second reason was practical: several of our exhibits relied on bulb-based analogies and on single- and double-slit light experiments, both of which needed a genuinely dark environment to work well. The dome gave us that controlled darkness.

Figure 1 — The dome’s steel frame under construction

Figure 2 — The completed dome on exhibition day

Figure 3 — The team inside the finished dome, with the Quantum Computer Model on display

2. Qubit Superposition

This was the first exhibit a visitor encountered after entering the dome. Here, we gave a brief history of quantum computing and explained the difference between classical and quantum computers, before introducing one of the most critical concepts in the field: qubit superposition.

We explained that a classical bit can only exist in one of two states, 1 or 0, while a quantum bit (qubit) has an additional state called superposition — a combination of both 1 and 0 — with a specific probability of collapsing into one or the other once it is observed. To make this tangible, we used a bulb analogy: visitors could touch the bulb themselves and watch it settle into different colors depending on when and how it was touched, mirroring how observation collapses a superposition state.

To set the wider context for everything that followed, we also displayed a timeline poster tracing the history of quantum physics — from wave-particle duality to entanglement to universal quantum computation — alongside a clear comparison between classical and quantum computing.

Figure 4 — Evolution of Quantum Computing poster, tracing the history of quantum physics

3. Double-Slit & Single-Slit Experiments

Here, we demonstrated wave-particle duality and quantum interference through a hands-on experimental setup, giving visitors a chance to see how abstract theoretical concepts can be shown through direct experiment rather than just explained.

Figure 5 — The single-slit and double-slit experiment apparatus

4. Bloch Sphere & Quantum Gates

This exhibit covered two linked concepts: the Bloch sphere model and quantum gates. One of the hardest things to explain was the equation describing a qubit’s superposition state:

|ψ⟩ = α|0⟩ + β|1⟩

We showed visitors how this equation can be modeled geometrically as a point on the Bloch sphere. To make it concrete, we built a physical ring fitted with a dial that served as a simplified Bloch sphere model. Alongside it, we built a mobile app that let visitors adjust the α and β values directly and watch the dial move in real time to the corresponding position on the sphere — letting them visually see the probability of the qubit collapsing to 0 versus 1.

We also implemented quantum gates in the app. Visitors could apply a gate and watch the dial move live to the new α, β position that gate produced. The app used Qiskit as its backend, so every rotation shown on the dial corresponded to a real, computed quantum state rather than a simulated approximation.

Figure 6 — The mobile app, showing the live qubit state |ψ⟩ = 0.515|0⟩ + 0.857|1⟩ with α, β, and θ values, alongside the Q-Ring and Qubit visualizers

Alongside the ring-and-app setup, we used a poster presentation to give more detail to visitors who wanted to go deeper into the underlying theory — covering qubit states on the Bloch sphere, the general quantum state equation, the classification of quantum gates, and a worked example of how the X gate transforms a qubit’s state.

Figure 7 — Bloch Sphere & Quantum Gates poster

5. Entanglement

Here, we used a two-bulb analogy to explain entanglement, paired with four physical switches representing the four Bell states. Visitors could select any Bell state and directly observe how entanglement manifested differently across each one.

6. Quantum Computer Model Demo

For the final exhibit, we built a physical wooden and metal model representing the shape of IBM’s quantum computers, which we used to explain their distinctive cooling systems to visitors.

Figure 8 — Our physical model of an IBM-style quantum computer, on display during the exhibition

Beyond the physical model, we let visitors build their own simple quantum circuits directly on the IBM Quantum Platform, giving them a chance to apply what they’d learned throughout the zone on a real quantum computing interface. In the example below, a Hadamard gate has been applied to a qubit, putting it into superposition — visible both as a 50/50 split on the probability chart and as the corresponding state on the Q-sphere.

Figure 9 — Building a circuit on the IBM Quantum Platform, applying a Hadamard gate and observing the resulting superposition

Closing Thoughts

Visitors arrived with little to no knowledge of quantum computing and left with a working understanding of qubits, superposition, entanglement, the Bloch sphere, and quantum gates.

This project gave us the chance to combine engineering creativity, leadership, and a genuine passion for quantum computing outreach — turning advanced theory into a real, hands-on learning experience for thousands of people who might never otherwise have encountered it.

Thank you for reading, and I look forward to contributing further to the field of quantum computing.