The Quantum Bit
Qubits
The Classical Bit
In classical computing, a bit is the fundamental unit of information. It can be either 0 or 1. Nothing in between.
Think of a light switch: it's either OFF (0) or ON (1). Simple and deterministic.
Interactive Classical Bit
Click to flip the bit , it's always exactly 0 or 1, nothing in between!
A classical bit is deterministic , you always know exactly what value it holds. No uncertainty, no probability.
💡 Compare this to the qubit demo below , notice the difference!
Enter the Qubit
A qubit (quantum bit) is the quantum version of a classical bit. Like a classical bit, when you measure it, you get either 0 or 1.
But here's the key difference: before measurement, a qubit can exist in a superposition of both states simultaneously.
Think of it like a coin spinning in the air, it's neither heads nor tails until it lands.
Interactive Qubit
Apply gates to manipulate the qubit, then measure to collapse the state!
The Math (Simplified)
We represent a qubit's state as:
Where:
|0⟩and|1⟩are the two basis statesαandβare complex numbers called amplitudes- |α|² is the probability of measuring 0
- |β|² is the probability of measuring 1
- |α|² + |β|² = 1 (probabilities must sum to 1)
Key Intuitions
Measurement Collapses State
Probabilistic, Not Random
More Than Randomness
Hands-on exercise
10-15 minutes
Goal , Understand qubits by creating and measuring them in different states.
Open in Google ColabReflection
- 01How is a qubit different from a classical bit in terms of the information it can represent?
- 02Why do you think we use probability amplitudes instead of just probabilities?