Qubit

A qubit is the basic unit of quantum information. Unlike a classical bit, a qubit can be in a superposition of basis states.

Intuition

A qubit is something you can rotate and interfere, not just store 0/1.

Math / formal explanation

A qubit lives in a 2D complex vector space, commonly written:

Example

The state $|+\rangle$ is a common superposition:

Turtle Tip

Common pitfalls

• Thinking “qubit = electron” (a qubit is an abstract state; implementations vary)

Quick check

1. What constraint must amplitudes satisfy?