Hey folks 👋
Welcome back to another SK NEXUS Deep Dive.
I’ve always loved learning new things, because I genuinely enjoy understanding how stuff works. But most of the internet doesn’t speak human anymore. Every article sounds like a PhD thesis, and that used to frustrate me.
That frustration is what brought me here. I couldn’t find simple explanations on many topics that’s why I started to write in such a way, for you.
Recently, I was working on a case study that involved writing about quantum topics for a technical audience. I expected it to be dull. Instead, I ended up going much deeper into the subject than I expected. Eventually I thought why not turn what I learned into something everyone can follow?
Because while we spend a lot of time talking about AI, another technological revolution has been developing in the background for decades.
Quantum technology has existed in research labs for much longer than most people realize. The first quantum revolution gave us the foundations behind technologies such as semiconductors. We are now seeing the beginnings of a second one, where quantum systems are being developed for computing, sensing, communication, and other applications.
For many years, quantum sounded like something out of a science fiction movie. That is becoming harder to say as governments, and researchers move these technologies closer to real-world use.
So, let’s start from the ground up and look at where quantum technology came from, what changed between the first and second quantum revolutions, and why Quantum 2.0 matters now.
Quantum 1.0 - The Beginning of It All
To understand where we are today, we need to rewind the clock.
Quantum computing didn’t just appear overnight, it’s built on over a century of discoveries in physics.
Before we could build quantum computers, we first had to realize that the universe itself doesn’t play by classical rules. That realization - that particles can exist in multiple states at once - is where it all began.
If you haven’t read The Evolution of Computers, I’d recommend checking it out. It’ll give you a strong baseline to connect the dots between classical and quantum worlds.
First, we would need to learn a bit of physics, but don’t worry, this isn’t a physics lecture. I’ll keep it simple, just enough physics to understand how we got here.
Setting the Stage
At the start of the 1900s, physics looked complete.
Newton had already explained planetary motion and gravity. Hooke had proven that light behaves like a wave.
At that time, to most scientists, the universe felt solved, but when researchers studied how light and heat behaved at microscopic scales, classical physics broke down and that’s when the cracks started showing.
Scientists were realizing that something fundamental is missing when they noticed that - hot metal didn’t glow the way the math predicted, Light acted like a wave one moment, and like a particle the next.
And that’s when a few rebels stepped up: Planck, Einstein, Schrödinger, and Heisenberg. Each of them questioning what everyone thought they knew about reality.
Together, they uncovered the truth which had been hidden from a long time.
And it all began with Planck, the man who proved that even energy comes in tiny chunks.
The Birth of Quantum Theory (1900s-1930s)
Max Planck (1900): The Birth of the Quantum
Max Planck was a German theoretical physicist.
In 1900, he discovered that energy doesn’t flow like water; it moves in tiny packets, which he called quanta. That one idea flipped physics upside down, proving that energy is quantized, not continuous.
In short, Planck showed that nature runs on chunks, not streams.
Albert Einstein (1905): Light Comes in Packets
Albert Einstein took Planck’s idea further. While Planck applied quantization to heat, Einstein applied it to light. Years after Hooke showed that light behaves like a wave, Einstein took a deeper look and realized it wasn’t that simple.
Light, he proposed, acts as both a wave and a particle. Each packet of light carried energy - what he called a photon. This idea explained the mysterious photoelectric effect.
In short, Einstein proved that light isn’t just a wave - it can act as a wave, a particle, or even both at once, depending on the circumstances
Schrödinger (1926): The Equation That Changed Reality
Erwin Schrödinger was an Austrian physicist.
He built a model called the wave function. Instead of telling you exactly where a particle is, it tells you where it’s most likely to be. You can’t pin down its exact position, but you can predict the odds of finding it somewhere.
In short, Schrödinger showed that in the quantum world, certainty dies and everything is a matter of probabilities.
Heisenberg (1927): The Birth of Uncertainty
Werner Heisenberg was a German physicist and no this isn’t the guy from Breaking Bad.
He was the type of guy who was unafraid to question the very idea of “knowing.” Instead of picturing what particles look like, he focused only on what could actually be measured.
That’s when he realized that the act of measuring itself changes what you’re trying to measure. You can know a particle’s position or its momentum, but never both at once. The more you know one, the less you know the other.
In short, Heisenberg proved that uncertainty is how nature actually works.
Tying the Threads
You’re probably wondering: “Why did I tell you all this?” Because these were the puzzle pieces of the same picture.
Planck showed energy comes in chunks.
Einstein proved light can act like both waves and particles.
Schrödinger and Heisenberg built the math to describe it all.
Together, they laid the foundation of quantum mechanics.
Quantum computing is literally the practical engineering of these same principles. Whatever term that you might have heard in the world of quantum computing such as qubit, entanglement…etc. All of them trace straight back to these early 1900s breakthroughs.
Now, that you have a general understanding of these concepts, you are on a solid path to understanding quantum computing not just memorizing cool tricks without knowing why they work.
When Theory Became Tech
Once the equations were cracked, it was time to test reality.
Scientists did what scientists do best. They started turning theory into tools. Because, as Oppenheimer once said, “Theory will only take you so far.”
And so began the first quantum revolution, the era where physics met hardware:
Transistor (1947) - The first real proof that controlling electrons could control information. Without it, no phones, no laptops, no internet.
Laser (1960) - Einstein’s photon theory turned into beams so precise they could cut steel or perform eye surgery - revolutionializing medicine industry.
Semiconductors (1950s - present) - Quantum behavior of electrons in silicon made chips, microprocessors, and integrated circuits possible.
MRI (1970s) - Medical miracle powered by quantum spin. You don’t see atoms, but quantum mechanics lets you map them.
Quantum 2.0: Where it started taking off
Welcome to Quantum 2.0. the era we’re living in right now.
The age where theory turned into computation, and quantum finally meant hardware, not just equations.
But how did it all start?
To answer that, we’ve got to time-travel one last time - back to the 1980s.
Don’t worry, I’m not dragging you through more dusty physics; just one final leap through time before we hit the fun part.
The Birth of Quantum Computing (1980-Present)
The Founding Era (1982-1999)
In 1982: Richard Feynman lit the fuse. He asked a simple question: “Why not build computers that work the same way the universe does?”
In 1985: Just three years later, David Deutsch took that spark and turned it into theory. He described a universal quantum computer, a machine capable of running any computation, just like a classical one, but powered by quantum rules.
Fast forward to the 1990s, things started getting serious.
In 1994: Peter Shor introduced an algorithm that could break modern encryption by factoring huge numbers exponentially faster than classical computers. It’s famously known as Shor’s algorithm.
In 1996: Lov Grover followed up with a faster search algorithm, showing that quantum computers could outperform classical ones even beyond cryptography. It’s famously known as Grover’s algorithm.
By 1999, D-Wave Systems was founded. It was the first company openly dedicated to building a quantum computer.
The Expansion Era (2000-Present)
In 2000: Edward Farhi and his team at MIT proposed adiabatic quantum computing.
By 2001: IBM and Stanford turned theory into reality, using a 7-qubit processor to run Shor’s algorithm. For the first time - they successfully demonstrated true quantum computation.
By 2010: D-Wave Systems released D-Wave One, calling it the first commercial quantum computer. Though limited, it proved that quantum hardware could leave theory behind.
In 2016: IBM opened its Quantum Experience to the public. For the first time, quantum computing was accessible - not just to scientists, but to anyone with an internet connection.
And in 2019: Google’s Sycamore processor achieved what was once thought impossible - quantum supremacy. It marked the moment quantum computing officially outpaced classical logic.
That was the short version of how quantum computing went from idea to impact.
And also just for your understanding - following is a rough outline of everything so far.
Quantum Basics: The Core Concepts You Must Know
So, you’ve made it through the history - congrats.
Now comes the real fun part: the fundamentals.
These are the core principles - the stuff you need to know if you want to sound like the cool guy who actually gets how this works.
Bit vs Qubit: The Core Difference
A bit (short for binary digit) is the smallest unit of information in classical computing. It can only exist in one of two states - 0 or 1. You can think of it like a light switch , it’s either off (0) or on (1).
Every program is built from billions of these bits flipping between 0 and 1
Bits are simple but they are also limited. On the other hand, a qubit (short for quantum bit) is the quantum version of a bit. But unlike a classical bit, a qubit can be 0 and 1 at the same time. This state is called superposition.
Think of it like a spinning coin: while it’s spinning, it’s both heads and tails. Only when it lands (when you measure it) does it become one or the other.
This “in-between” state allows quantum computers to process many possibilities at once. That’s why a few qubits can outperform millions of classical bits.
Coherence: The Lifeline of Quantum Computing
Earlier, I talked about superposition. I mentioned how it is the qubit’s superpower, but what I didn’t mention is that, it’s also its greatest weakness.
Qubits can, in theory exist as both 0 and 1 at the same time, but that state is ridiculously fragile. A tiny bit of heat or even a whisper of noise can knock a qubit out of superposition and force it to “collapse” into a definite 0 or 1.