Quantum Computers: The Weird Science of the Small
Tags: computerscience, quantum, datascience, performance
Published: 2023-05-08 03:08:21

Quantum physics is an emerging and frankly baffling science that humanity is still struggling to understand. Its findings are confusing and even sometimes appear to be impossible given our current understanding of physics, but nonetheless have lead to designs of computers that could potentially greatly accelerate our ability to conduct experimental simulations, transmit information, or even enhance the processing speed of our current PCs.

But what is a quantum computer exactly? To understand it, we must first examine how our current computers function.


![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/rd3ijfkwrnm1mms8sql9.jpg)

Traditionally, the computers that are most in use today operate by using 'bits' at the base level. Bits are essentially switches that are either on (have power running through them) or off (don't have power running through them) at any given time; these are read as the 1's and 0's that most people know of. These 1's and 0's are known as 'binary code', and is used as the basic building blocks of a computer. Every process that we program in, every image or video we view from our monitors, every change that happens as a result of a keyboard button press or mouse click, all are essentially the result of programming languages being translated into (or reading) binary code. 

Quantum computers, however, use something different from a bit: a "Qubit" (pronounced CUE-bit). Qubits are quantum particles which you can envision as a sphere with a point inside of it which is constantly in motion; that point can at any time be in any position within the sphere. Because of this, a Qubit can equal 1, 0, or anywhere in between!. This concept is known as "Superposition". Here is a visualization of a Qubit:


![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/d55h5t5s64y5nbw4b87o.gif)

Qubits (and quantum particles in general) have a few interesting properties. For one thing, while a Qubit _can_ be, say, 0.42 for instance, the moment it is actually measured or observed in any way, even secondhand through, for instance, the radiation it emits, its value will "collapse" into either a 1 or a 0 - nothing in between. This, of course, makes them difficult to measure properly, however another interesting property of the Qubit does assist to some extent: entanglement. 

If 2 or more Qubits are close enough to each other, they will become "entangled". If two entangled Qubits are measured at the same time, they will each always yield the same result - that is to say, for 2 entangled Qubits measured at the same time, their measurements would always be either 1 1 or 0 0; never 1 0 or 0 1. An especially intriguing aspect of this property is that it is true regardless of distance! If 2 entangled Qubits are on the opposite side of the planet, they will still always yield the same value if they are measured at the same time.

So how do we measure Qubits such that we can use them in the same way we use bits in a computer? The answer is a concept known as "interference", which involves measuring Qubits strategically at certain points according to a complicated quantum algorithm known as "Grover's Algorithm" (seen below)


![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/yj0jjj3l1bs7eirhr9v8.png)

Now, the math of that algorithm is beyond me, but the effect is understandable: using said algorithm, it is possible to get a Qubit's true value, effectively expanding the amount of information a single Qubit can contain when compared to a traditional bit. To give some context, a quantum computer with only 10 qubits would theoretically have a storage capacity equal to 2^10 (1,024) values, which would require 16,000 bits in a traditional computer. For a traditional computer to equal the computational power of quantum computer that had 500 qubits, it would require more bits than there are atoms in the known universe!


![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/os0pehz9wbl0fvuyrx0n.jpg)

This technology is still new, and though some functional quantum computers _have_ been made, but only on a small scale and certainly not in any way that would be commercially viable. Still, as the field grows and becomes more refined, who knows what wonders the quantum computer might unlock?


<u>Sources</u>

https://www.youtube.com/watch?v=jHoEjvuPoB8

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