Quantum Computers, Stable Marriages, and the Intimidating Future we will Witness
By: Agbo Dozie
Tags: IBM, Quantum Computing, Artificial Intelligence, Qiskit, Algorithms

Credits: Trendintech

I do not believe in spirits. Reality is either classical or quantum, approximately. Classical, as in visible, and quantum, as in sub-atomic or too small for the naked eye. The world of the quantum is a fascinating one. One where it is difficult to separate imagination from reality; a beautiful intersection — one of uncertainties and miracles. Miracles. Miracles like being simultaneously dead and alive, being at more than one place at a time, miracles that made Einstein accuse God never to play dice! For quantum oddities, even God was summoned to the labs. If for nothing else, God must have thought of physicists as more daring than two million Alexander the Greats combined. But this is not about who has a broader courage, it’s about mathematics, and the revelations that come from pruning reality with it.

In this article, I make an attempt at describing the physics powering the new cutting-edge technology of quantum computing. I end by introducing the technology. In a sequel, I will dig deeper.

In the spirit of going deep, what would your response be if you were to be asked what will be found in a single piece of your skin if you looked closely enough? Go ahead, make a guess. Tiny flashy matter? Could it be elastic black or white stuff? Or just stuff unknown? Well, we find atoms. By even drilling deeper, we encounter atomic constituents — from electrons to protons and quarks. These little beauties make us up from blood to cells and skin, they are the magic. At that scale reality changes and quantum mechanics is dedicated to understanding what goes on in that strange realm. What we find have far-reaching consequences.

One is a limit on determinism. What this tells us is that there is fundamentally a limit to how much we can know about truth, about the position and speed of a particle for example. Shoot a golf ball. You can estimate the speed and approximate its position to high degrees of accuracy, maybe to 12 decimal places. However, this is not a problem physically because we are classical bodies, and so a measure that detailed is insignificant. It is a huge deal in quantum mechanics, so important that it has come to be known as Heisenberg’s Uncertainty principle — you cannot know the position and speed of a subatomic particle simultaneously.

So then you may wonder, how do we measure quantities precisely in quantum mechanics? We do not. We guess, we calculate probabilities. It is these probabilities that we superpose together — and collapse in a process known as decoherence — to compute the reality of the particle we are trying to measure. This is the idea demonstrated by the hypothetical experiment put together by Erwin Schrodinger in his 1935 talk with Einstein.

Schrodinger’s Cat

In Quantum Mechanics, it is possible to be dead and alive at the same time! As ridiculous as that sounds, it is the cornerstone of the next generation computers that threatens to break your bank encryptions. We have stated that quantum mechanics is about probabilistic realities; so Schrodinger imagined that if we had a cat in a box with a poison jar and a means to break the jar, it is possible it will break it as much as it she might not. This means there is almost equal chance that the cat would be dead and alive. But how do we deterministically know? We cannot! We combine both solutions and conclude that the cat is in fact dead and alive.

Quantum computers are a consequence of this simultaneity. As opposed to bits in classical computers, they are powered by Qubits (Quantum Bits). These bits, unlike classical bits which are either 0 or 1, are 0 and 1 at the same time. Isn’t this strange? You are not alone, it is Hogwarts! But stick with me, with us as we briefly explore some realities of this magical dimension of our world.