What is Quantum Computing?

Imagine you have a light switch. It is either ON (1) or OFF (0). That is how classical computers work — they store and process information in bits, which are just 1s and 0s.

Now imagine a dimmer switch instead of just ON or OFF. A dimmer switch can be fully ON, fully OFF, or anywhere in between — and even more magically, it can be in multiple states at once until you check it. That is how a quantum computer works, with qubits instead of bits.

Let's look at another example: Imagine you are looking for a friend in a huge crowd of thousands of people.

• A normal computer is like checking one face at a time — fast, but still slow if the crowd is massive.
• A quantum computer is like suddenly being able to look at all faces at once and instantly spotting your friend.

How does it do that?

Magic of Qubits, Superposition and Entanglement

Instead of working with plain bits (0 or 1, like a light switch that’s ON or OFF), quantum computers use qubits.

A qubit is the quantum version of a bit.

• A bit is either 0 or 1.
• A qubit can be 0, 1, or a mix of both at the same time — like a spinning coin that is both heads and tails until it lands. This “mixing” is called Superposition.

This “both at once” ability lets quantum computers explore many possibilities simultaneously instead of one by one. Qubits are powerful, because of Superposition with which a quantum computer can explore many different possibilities in parallel.

Entanglement:

• Two or more qubits can be linked in such a way that the state of one instantly affects the other — no matter how far apart they are.
• This strange property was famously called “spooky action at a distance” by Einstein.
• Let me explain with an example: Imagine you have two magical dice. Normally, if you roll two dice, you don’t know what numbers will come up — and each is independent. But if these dice are entangled, something strange happens. No matter how far apart they are — let's say one is in your hand (in Hyderabad - INDIA) and the other in Dallas (US) — the moment you roll one die and see the number, the other die will instantly show a matching result in Dallas.
• It is as if they are mysteriously have invisible connection.

Technically, Entanglement happens when two (or more) particles share a single combined quantum state. That means you can not describe one particle’s state independently; you must describe the system as a whole (confusing right.. don't worry i will simply in upcoming chapters)

Why it Matters in Engineering & Tech

• Quantum Cryptography (QKD) – uses entanglement for secure key exchange.
• Quantum Teleportation – transfers quantum information via entanglement + classical channel.
• Quantum Networks – entanglement is like the “fiber optic cable” of quantum internet.

That is all for today.