In an earlier article we talked about 10 companies working on quantum computing and promised our lovely readers a follow up article on companies working on “quantum cryptography” and/or “quantum encryption”. As we sat down to write that article, we realized that we had no idea what quantum cryptography actually was. In fact, we don’t even know what the definition of the word quantum is. We’ve heard the word quantum used to describe quantum physics, quantum mechanics, quantum science, and quantum theory. What do all these terms mean and how do they relate? If you’re going to invest in a particular type of technology, then you need to have a basic understanding of it first. We’re going to get to the bottom of all this quantum stuff *right now. *

**What is the Definition of Quantum?**

The word quantum is actually Latin for “amount”. The definition of the word quantum is the “smallest possible piece of anything”. For example, the smallest piece of visible light is referred to as a “photon” or “light quantum”. *A quantum is the smallest unit of something.*

#### What is the Definition of Quantum Physics?

Firstly, we need to know what physics is. Physics is an area of science where the main goal is to understand how the universe behaves. Intuitively then, “quantum physics” would be defined as the study of “how the smallest piece of the universe behaves” which kind of makes sense when you think about it. *Quantum physics is the study of the universe at a very, very small scale. *This is what Einstein spent a lot of his time doing.

#### What is the Definition of Quantum Science?

*Quantum science is the study of the applications of quantum physics like quantum computing, cryptography or nanotechnology.*

**What is the Definition of Quantum Theory?**

This is where our subject matter gets a bit more complicated so we decided to paste the “The Development of Quantum Theory” from WhatIs.com below for you to have a look:

The Development of Quantum TheoryIn 1900, Planck made the assumption that energy was made of individual units, or quanta.

In 1905, Albert Einstein theorized that not just the energy, but the radiation itself was

quantizedin the same manner.In 1924, Louis de Broglie proposed that there is no fundamental difference in the makeup and behavior of energy and matter; on the atomic and subatomic level either may behave as if made of either particles or waves. This theory became known as the

principle of wave-particle duality: elementary particles of both energy and matter behave, depending on the blah blah blah blah blah….

It’s at this point that we’re starting to nod off. The problem with researching all this quantum stuff is that it can suddenly get incredibly ~~technical~~ boring in no time at all. It’s usually around this time that we like to throw a bit of humor out there to make sure everyone is still awake:

Still with us? Good.

Here’s a definition of quantum theory that is much simpler. *Quantum theory is the set of fundamental rules and principles that govern the world of quantum physics. *One example of quantum theory is quantum mechanics.

**What is the Definition of Quantum Mechanics?**

Y’all remember what nanotechnology is, right? Nanotechnology is the science of the *very* small. As you get down to smaller and smaller sizes, you eventually get to the “quantum scale” or quantum realm” which is defined as dimensions of 100 nanometers or less. In other words, nanotechnology is working at very very small scales where some seriously wacky stuff starts to happen. For example, a nanomaterial called “graphene” has some amazing properties like being the stiffest material known to man and the most impermeable material ever discovered. The reason for this wacky behavior is because of “quantum mechanics” which are a different set of rules that apply at a “quantum scale” of 100 nanometers or less. *Quantum mechanics are special rules that apply when you start working with very small things.*

**What is the Definition of Quantum Computing?**

Regular readers will already know this but if you just joined us, take a second to read this article which talks about how quantum computing differs from computers today. While the number of people predicting the end of Moore’s law seems to double every year (*ba dum tsh*), we will eventually reach the end of it using today’s computing technology. Quantum computers are millions of times faster than today’s computers because they work completely differently. In today’s computer, everything is “either a one or a zero” while in quantum computing, “everything is a one, a zero, or anything in between”. In other words, it’s kind of like how some people view gender these days except quantum computing seems far easier to understand. *Quantum computing refers to a completely new type of computer that uses quantum mechanics to perform at levels that are millions of times faster than the computers we use today.*

**What is the Definition of Quantum Cryptography?**

Cryptography is the study of secure communication between two parties while assuming that everyone else can access the communication. In other words, I create a message that only you can decode with a special key but that everbody can see. Currently, we use mathematics to “encrypt” messages and then you need to have a special key to open them that nobody else has. The problem is, someone could hack into that message and neither of us would be aware of the security breach. Now it’s true that in most cases you would need millions of years to “hack” the key to decode a message with today’s computers, but what happens when we start using quantum computers to crack these codes?

Now let’s talk about a completely wacky form of cryptography called quantum cryptography. Remember those photons we talked about earlier? What quantum cryptography does is to take photons and then turn them into keys as seen below:

Now here’s where it gets crazy. If a third party actually looks at the photons while they are being transmitted, they will change and then the receiving party knows there has been a security breach. While some research shows that quantum cryptography could be hacked, it is widely assumed that the laws of physics will not allow for that to happen. At the very least we could make the following claim. *Quantum cryptography uses the properties of quantum physics to give us the most “secure” form of communication available.*

**What is the Definition of Quantum Encryption?**

Since quantum cryptography is the study of how to encrypt a message using photons, quantum encryption refers to the act of actually embedding the message in the photons. At least that’s what we think because we actually couldn’t find any proper explanation of how the two differ. *The main takeaway here is that you can refer to the whole “quantum cryptography/encryption” thing as just “quantum cryptography”.*

Now that we’ve defined everything quantum we can think of, it’s time to move on to our article about quantum cryptography and quantum encryption. We’ll be right back after these messages.

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