How do qubits work and differ from classical bits?

The primary difference lies in how they store information, which is dictated by two unique quantum properties: superposition and entanglement.

Classical Bit (The "Light Switch"):

A classical bit is a simple, binary switch. It has only two possible states: 0 (off) or 1 (on).

It is predictable and follows the laws of classical physics. At any given time, it is definitively one or the other.

Qubit (The "Spinning Coin"):

A qubit is a quantum bit. It can be any quantum system, like the spin of an electron (up or down) or the polarization of a photon.

Superposition: A qubit does not have to be just 0 or 1. Thanks to superposition, it can be a combination of both states at the same time, much like a spinning coin is neither heads nor tails until you measure it. This allows a quantum computer to explore many possibilities at once. While 2 classical bits can store one of 4 states (00, 01, 10, or 11), 2 qubits in superposition can represent all 4 simultaneously.

Entanglement: Qubits can be linked together in a way that is impossible in classical physics. When qubits are entangled, their fates are intertwined.If you measure one qubit, you instantly know the state of its entangled partner, even if it's miles away.

In summary, a classical bit stores one value. A qubit uses superposition to store multiple values at once and uses entanglement to link its state to other qubits, creating exponential processing power.