The knowledge base · From Meet 1

Quantum foundations

Learn the core concepts.

Quantum computing isn't just faster math: it leverages the laws of physics at the atomic scale. Here are the core ideas we cover, each with the plain-language analogy we use in the room.

01 / core ideas

Building Blocks

Superposition

A qubit isn't just 0 or 1, it holds a combination of both at once. Think of a spinning coin: while it spins it's both heads and tails.

Analogy: Spinning coin. 2 qubits represent 4 states at once; 300 qubits hold more states than there are atoms in the observable universe.

Entanglement

Qubits can be linked across space, and measuring one instantly dictates its partner. Flip one coin in Visakhapatnam and its twin in New York lands the same way.

Analogy: Telepathic coins. Entangled qubits behave as one unified system; measuring the first gives you the second for free.

Measurement

Looking at a quantum state collapses its possibilities into a single classical reality, like a camera freezing the spinning coin. And it's fragile.

Analogy: The camera. Any stray heat, vibration or light acts as an unintended measurement and destroys the calculation.

Beyond qubits

We aren't limited to binary. Qudits hold more than two states (a spinning 6-sided die); qumodes handle continuous waves of information (a dimmer switch).

Analogy: Multi-lane highway. Qumodes are especially powerful for deep quantum learning and AI optimisation.

Quantum gates

If qubits are raw material, gates shape them: physical operations like laser pulses or microwave bursts, placed along a wire to form a circuit.

Analogy: Sheet music. H spins the coin · X flips it · Z is a phase flip · Measure is the camera · CNOT entangles two qubits.

NISQ era

Today we have 50 to 1,000 fragile physical qubits with no full error correction, the Noisy Intermediate-Scale Quantum era. So we lean on hybrid CPU+QPU loops.

Analogy: The bridge. breakthroughs like neutral-atom arrays and qLDPC codes are shrinking the overhead toward fault tolerance.

02 / Hands-on

Spin a qubit. Run 1024 shots. Watch the probabilities.

Quantum outputs are probabilistic: you run the same circuit many times ("shots") and read a distribution. Build a tiny 2-qubit circuit below and run it, exactly like we do on IBM Composer.

03 / The developer stack

You don't need a PhD in physics.

Modern tools bridge the gap from visual circuit diagrams to real code running on cloud quantum processors.

OpenQASM

01 · LANGUAGE

The human-readable "assembly" for quantum, a text representation of the circuit timeline.

IBM Quantum Composer

02 · PROTOTYPE

A drag-and-drop web interface to visually build and test circuits, where our hands-on lab happens.

Qiskit

03 · CODE

IBM's open-source Python SDK to program, simulate, and send workloads to real QPUs over the cloud.

// a Bell state in OpenQASM 2.0: superpose q0, then entangle q1 OPENQASM 2.0; include "qelib1.inc"; qreg q[2]; creg c[2]; h q[0]; // Hadamard → superposition cx q[0],q[1]; // CNOT → entanglement measure q -> c; // collapse & read

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