Superposa

Meet Superposa, a qubit who is a blend of 0 and 1 until someone looks.

In quantum mechanics a system can be in a superposition of states. For a two-level system, a qubit, the general state is α|0⟩ + β|1⟩, where α and β are complex numbers called amplitudes. Measure it and you always get either 0 or 1, never something in between. The Born rule gives the odds: 0 with probability |α|², 1 with probability |β|², and the two add to 1.

Example: with α = β = 1/√2, each outcome has a 50 percent chance. After the measurement, the qubit is left in the state that was found.

Superposition is more than ignorance. Amplitudes can interfere, adding or cancelling like waves, which is what the double-slit experiment shows. Quantum computers use superpositions of many qubits together with interference to solve some problems more efficiently than ordinary computers.

Superpositions are fragile. Interactions with the environment cause decoherence, which is why quantum computers need careful isolation, and why everyday objects don't appear to be in two states at once.