Quantum Physics & Computing

I am coming up with another series to explain quantum computing in a way anyone can understand — even if you have never studied physics or computer science.

We all know computers — phones, laptops, game consoles — they work using 0s and 1s. They follow clear rules, and we can predict what they will do. But nature does not always work that way. In the tiny world of atoms and particles, things can be in two places at once, change instantly when something far away changes, and act in ways that seem impossible. This strange world is called quantum mechanics.

Quantum computers use these weird rules of nature to do things that normal computer can not, like solving huge problems very quickly. They could help discover new medicines, make better climate models, or find the fastest route across a busy city.

In this blog, I’ll keep it simple. No heavy math. No complicated science talk. Just easy examples and clear explanations so you can follow along step-by-step.

By the end, you will know (hopefully :-) ) what quantum computing is, why it matters, and where it might take us.

Let’s start our journey into the quantum world

Happy Journey folks --- Let's start .......

Before we can understand quantum computing, we need to understand quantum.

What does “quantum” mean?

The word “quantum” comes from the Latin word quantus, meaning “how much.” In physics, a quantum is the smallest possible amount of something — like the tiniest packet of energy, matter, or information that can exist.

For example:

• A single photon is a quantum of light.
• A single electron is a quantum of electric charge.
• In sound, the smallest unit of vibration energy is a phonon.

In the classical world (our everyday experience), things can vary smoothly — for example, you can dim a lamp gradually. But in the quantum world, certain properties only change in discrete jumps — like climbing stairs instead of walking up a ramp.

Another example could be.. In the classical world, you can turn the volume on your speaker up or down as smoothly as you like. But in the quantum world, it would be like your speaker only having a few fixed volume levels — nothing in-between — so it jumps from soft to medium to loud instantly.

The birth of quantum physics

At the start of the 20th century, scientists discovered extremely tiny scales — atoms and subatomic particles — the world behaves very differently from what Isaac Newton’s laws predicted.

Key discoveries:

• Max Planck (1900) — Energy comes in discrete chunks (quanta), not in a smooth flow.
• Albert Einstein (1905) — Light acts like both a wave and a particle.
• Niels Bohr (1913) — Electrons orbit atoms in fixed energy levels, not anywhere in between.
• Werner Heisenberg (1927) — Uncertainty principle: you can not know a particle’s exact position and speed at the same time.

These findings built Quantum Mechanics — the rules for how particles behave at the tiniest scales.

Weird quantum rules that inspired computing

Three of these quantum principles became the foundation for quantum computers:

• Superposition A quantum particle can be in multiple states at once until measured. Example: A qubit can be both 0 and 1 until you check it — like a coin spinning in midair.
• Entanglement Two particles can be linked so that changing one instantly changes the other, no matter how far apart they are. Example: Imagine two magic dice — roll one and the other always matches, even if they are on opposite sides of the Earth.
• Quantum Interference is, different possibilities in a quantum system mix together. Some combine to make certain outcomes more likely, while others cancel out to make some outcomes less likely — something like waves in water adding up or flattening out

From theory to technology

The idea of using quantum physics for computing was first proposed in the 1980s by Richard Feynman and David Deutsch.

• Feynman realized that simulating quantum systems with classical computers is incredibly inefficient — but a quantum system could simulate itself naturally.
• Deutsch extended this to propose a universal quantum computer that could, in theory, perform any computation.

Example — Classical vs Quantum simulation

• Classical: To simulate a molecule with 50 electrons, you would need more memory than all the atoms in the Earth.
• Quantum: A quantum computer with 50 qubits could represent all those possibilities naturally.

Why “quantum” matters to computing

Instead of storing data as a sequence of definite 0s and 1s, quantum computers use quantum bits that can explore many possibilities at once. This parallelism is why quantum computers can, for certain problems, outperform classical machines by staggering margins.

You know the background now.