# Quantum Computing: The Hottest Application of Quantum Mechanics

## Introduction

All computers, from Charles Babbage’s Difference Engine No. 1 to the HP Spectre I used to type this very piece, run on a base 2 number system binary. The two numbers are 1 and 0, which signifies on and off. Although this simple language has enabled computers to render high end graphics, create music, and can even allow IBM’s Watson to defeat Jeopardy’s reigning champions in 2011. Now computer scientists and physicists are teaming up to utilize the strange world of subatomic particles to greatly increase the processing power of computers. Quantum computers(aka non-classical computers) will be able to tackle problems that classical computers are currently incapable of doing. To truly understand how these computers operate, one will have to understand some basic principles of quantum mechanics.

## What is Quantum Mechanics?

First and foremost, quantum mechanics studies the behavior of matter and light on the subatomic scale. This field of study attempts to explain the strange and contradictory nature of the subatomic universe.

## Basic Concepts of Quantum Mechanics

Quantum mechanics was birthed from Max Planck while studying the “ultraviolet catastrophe”. According to the laws of classical physics, if you created a black box that does not allow any light to escape, then the box would be producing infinite amounts of ultraviolet radiation and heat, however nothing happens.

To explain this conundrum, Planck assumed that light is not a wave, but rather, it is made up of particles, and he built his equations assuming this was true. In 1905, Albert Einstein concluded that light is both a particle and a wave. In 1926, Gilbert Lewis called these light particles, photons.

In 1913, Niels Bohr formulated the Bohr atomic model to explain the structure of atoms using the principles of quantum mechanics. This was later revised to consider discrete states, where electrons jump between orbits, though in reality, the atomic model is not flat.

Erwin Schrödinger devised a mathematical formula that explained Louis- Victor de Broglie’s wave hypothesis, which dictates that matter has the properties of both waves and particles and that their wavelengths are related to their linear momentum. The Schrödinger equation is used to learn the following about an orbital:

- The size of an orbital (n)
- The shape of an orbital (l)
- Where the orbital is oriented in space(m)

## Schrödinger’s Cat

Schrödinger also devised the famous Schrödinger’s cat thought experiment to explain superpositions. A superposition is defined as an object that exists in multiple states at once. In his thought experiment, he asked people to imagine a cat locked in a steel box. The box also has a Geiger Counter linked to a bomb. The rate of radioactive decay is random, so there is no way to predict when the bomb will explode. Once the radiation reaches a certain level, the bomb will go off and kill the cat. If someone was to open the box, then the bomb will go off, thereby killing the cat. Until the box is opened, there is no way of knowing if the cat is alive or dead, so the only way to know anything about the cat is to assume that the cat is both simultaneously dead and alive (superposition). Therefore, the cat could be in one of the states, they are alive, dead, or a superposition that is both dead and alive at once. Once you find out if the cat is dead or alive, then the superposition does not exist.

## What can Schrödinger's cat teach us?

## Spin

In 1928, Paul Dirac demonstrated that particles have a 4^{th} quantum number which describes the “spin” of the electron. The spin is the angular momentum of the electron’s electromagnetic field. In Schrödinger’s equation, it is denoted as m_{s}. The spin plays an important part in non-classical computing due to a feature called quantum entanglement, which will be covered later.

## How does Non-Classical Computing Work?

## Qubits

Non-classical computing uses the ability of particles to exist in multiple states at once. It uses quantum bits(Qubits) to store information. However, unlike classical bits, qubits can be either 0, 1, or they can be both a 0 and a 1 at the same time.

This allows for vastly superior processing power in comparison to a classical computer because 1 qubit would be able to hold more information than a classical bit.

## Quantum Entanglement

Non-classical computers also take advantage of quantum entanglement to work effectively. Quantum entanglement means that if one particle spins in one direction, then the other particle will spin in the opposite direction. If we were to know everything about the particle, then the superposition would be lost and we would just have a classical computer.

## Applications of Non-Classical Computing

These computers can be utilized in a broad array of fields ranging from medicine to engineering. D-wave’s quantum computers can be used to reduce the damage caused by chemotherapy by creating thousands of simulations of the patient being injected with varying doses of chemo drugs and radiation to find the optimal dose that does the least damage to the human body.

Non-classical computers are also capable of discovering new drug treatments by testing thousands of molecular structures to find stable proteins that researchers can then replicate and study. It can be used to create more accurate weather forecasts, hyper-personalize advertising, and much more!

Despite these remarkable capabilities, non-classical computers will not replace out current laptops. This is because they will take more time to do mundane tasks such as watching YouTube videos, playing computer games, and writing documents. They take more steps to complete these tasks than a classical computer. They go through every possibility till it finds the best solution.

## Conclusion

All in all, quantum mechanics is the study of matter on a sub-atomic level. This branch of physics has the potential to revolutionize Information technology by dramatically increasing the processing power of computational devices via the use of quantum entanglement and superpositions. Although, non-classical computers can revolutionize the fields of advertising and pharmaceutical research, they are not a replacement for classical computers. Rather, they are an aid to classical computers. Although non-classical computers will not be replacing your desktop or your smartphone, they still have the potential to revolutionize the world we live in.

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## Works Cited

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Ekspong, Gösta. "The Dual Nature of Light as Reflected in the Nobel Archives." *Nobelprize.org*. Nobel Media, n.d. Web.

*How Does a Quantum Computer Work?* Dir. Derek Muller. *Youtube*. Veritasium, n.d. Web.

"Quantum Mechanics." *PBS*. Public Broadcasting Service, n.d. Web.Squires, Gordom Leslie.

"Quantum Mechanics." *Encyclopædia Britannica*. Encyclopædia Britannica, Inc., 24 Feb. 2017. Web.

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## Questions & Answers

**© 2017 Marcus T Caine**

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