Quantum Computing For The Average Joe

Imagine a regular computer, such as a MacBook Pro sitting on your desk. Conventional computers are made out of silicon computing chips. These chips contain millions of transistors. Think of a transistor as a light switch. A switch only has 2 states. It is either on or off. There is no in between. A light cannot be on and off at the same time. A transistor is similar to a light switch. It can be either “on” or ”off” to represent a value of either “1” or “0”. This is also called binary. Imagine a computer as millions of little kids doing simple math problems.

Now let's talk about quantum computers. Quantum computing is built upon quantum mechanics, a fundamental theory in physics. Quantum mechanics deals with nature at the smallest scales of atoms and subatomic particles. One thing to note is that quantum mechanics is very bizarre. It has puzzled scientists for many years. A lot of it will contradict what you learned in high school physics class.

Quantum computers deal with “quantum bits” or qubits. Instead of only being able to represent 1's or 0's, qubits can represent multiple values simultaneously.

This is known as the quantum effect called superposition. Another important quantum effect is called entanglement. Entanglement allows one to link all qubits together. When you put 2 qubits into entanglement and link them, what happens to one will happen to the other. Even if the 2 qubits are lightyears away from each other, action to one will mean action to the other.

The properties of qubits are what makes quantum computers so powerful. Imagine a regular computer is trying to query a database for the name “Johnny Appleseed”. A conventional computer might have to look at every single database entry until it finally finds the desired name. However, qubits can try all of the paths at once - speeding up the process. 20 qubits can store 1,000,000 values at once in parallel.

However, you may be asking one question. If a qubit can store multiple values at once, what is its true value? This is where a problem arises. Imagine it is your birthday. There are 100 boxes on a table. A box could contain a birthday gift (food, money, clothes) or nothing. All the boxes are closed. At this point, there could be any combination inside the boxes and the boxes are in a state of quantum superposition.

However, once you open one box, all the other boxes open. Before you opened the box there were an infinite amount of possibilities. However, you can only figure out what is in the boxes by making a measurement. However, this makes the attempt futile.

This is where an important part of quantum computing comes in. A qubit can be more than just being 1 and 0 at the same time. A qubit can store any number called an amplitude. An amplitude can be positive, negative, or even a complex number. The true goal of quantum computing is that for the incorrect answer or query, some of the qubits leading there will have positive amplitudes and some will have negative ones. The qubits will eventually cancel out. The path leading to the right answer will not cancel out.

There is one other important property of qubits. It is that they are very sensitive and fragile. It is paramount to maintain the state of entanglement and superposition of quantum computers to work.

If some of the content above flew over your head or didn’t make any sense - do not fret. The world-renowned physicist Richard Feynman said this about quantum mechanics: “If you think you understand quantum mechanics, you don’t understand quantum mechanics”

Quantum computers will revolutionize humanity. However, you will most likely never see them on your desk or at a school. Here will be some of their main use cases:

  • Ruining our current security systems. Most of your usernames and passwords are kept secret using an encryption method called Public-key cryptography. This consists of 2 keys - a public and private key. The public key is normally your username. The private key is normally your password. One problem is that your private key can be calculated using your public key. However, with current computers, the calculation would take years and would not be worth it. With quantum computers, it could be a breeze to find passwords.
  • Simulations. Currently, doing simulations are resource intensive. Simulating the quantum world is nearly impossible. Even simulating a molecule of Glucose is very difficult. Quantum computers could allow us to run simulations of biological systems and help understand them better.

As of this writing in late 2017, quantum computers are still far away. Researchers have been able to build simple computers with tens of qubits. However, these are test systems and are far from being stable. They are many teams working on quantum computers. Researchers are confident that we can see quantum systems for sale by 2025.



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