The Mind-Spinning Reality of Quantum Computers
Quantum what?
Imagine yourself working on a project that could one day revolutionize science. This computer is a leap in physics. Another giant step for humanity. For better or for worse, this computer will be one of the most monumental factors in the fate of the future. And you, are the one that's making it all happen. You have created wonder in the world. Excitement, curiosity, and fear. But what is this incredible machine? What does it do? What will it do? How does it do it? The answer to these questions induced me to literally start jumping up and down out of excitement. If your reaction isn't similar, I'd have to agree with Bohr when he stated “Anyone not shocked by quantum mechanics has not yet understood it.” Because it is simply beautiful.
Quantum who?
Quantum mechanics is the study of the laws of nature on a smaller scale of atoms and particles. It became a topic of interest largely in the early 1900's but had been attempted to be understood as far back as the 17th century when scientists like Robert Hook began studying light waves.
The most well known scientist to have studied light, color, and other behaviors tied to quantum mechanics might have been Max Planck. Planck's hypothesis is called the photoelectric effect and states all electromagnetic radiation occurs in photons by quantizing. The photoelectric effect is dependent upon the "particle picture" of light and therefore proves Planck's hypothesis correct.
Einstein wrote his General Theory of Relativity based on the Photoelectric effect and Heinrich Hertz's discovery in 1887 on ultraviolet illuminated electrodes creating electric sparks more easily. Basically, Einstein's relativity explained data about why the photoelectric effect is the result of light energy being carried in packets which proved Planck's ideas right. Einstein won his nobel prize in 1921 for his work. As a result of proving Planck's hypothesis correct, both energy and frequency were linked and therefore Planck's constant, which you've probably heard of, emerged. Understanding how particles interact and behave, especially light and color waves (see in next paragraph) is vital in pursuing quantum mechanics let alone a quantum computer.
Quantum how?
Quantum mechanics may have started in 1900, but quantum computing didn't begin till 1981 which is completely understandable as it was just the beginning for computers in general around that time! Richard Feynman, you've probably heard of him, very famous physicist dude, asked if humans could simulate physics on a computer at a conference at MIT. Some of it, was the answer.
Think back to quantum mechanics, a lot of information to take in, right? That's the exact problem we run into when trying to simulate it on a computer. It's just has too many variables. There's a more scientific way to describe this, something I learned from an article I read. One particle can be described by two variables so to describe a very basic variable (n) it'd be 2n. If we have 150 particles then we have 2150 variables which is a such a large number it'd be extremely irrational to build a computer with that much memory. Impossible even.
So what can we do? We'll let Feynman answer that one. Feynman postulated we use its seemingly restricting weakness in a positive way. If we can't simulate physics on a regular computer, why not simulate it on a quantum computer. A more powerful, faster, bigger computer. After that, nothing happened. The end.
No, I'm just kidding, but the idea was put to rest for a couple years after it was proposed. The possibilities were just too insane to comprehend at the time, too bizarre to even know where to start. In that time not a lot of research or experimentation was done. Nevertheless, Feynman persisted until he banded together a group of enthusiasts and the idea began to be put in action.
You probably know that the color an object reflects is determined by the colors of light it absorbs and reflects. On an atomic level we've found that when electrons rotate along the nucleus they can steal a photon making them change orbits around the nucleus. Each atom only absorbs and emits color of varying specific frequencies. Hydrogen has 4 colors. Why? Niels Bohr. Curious human being in my opinion, but a good scientist, at least most of the time, proved by things like this discovery I'm going to tell you about that led to his nobel prize. Scientists had been searching for decades for a way to predict what color a specific atom might be. It wasn't until 1913 this question was answered. Bohr proposed the classic scientific inquiry, "maybe what's really going on isn't what we think is going on," Luckily in the 1900's people weren't so eager to kill anyone who had an idea. Heaven forbid an idea that could attack a religious normality like the sun orbiting around the earth. He thought maybe atoms are behaving in accordance to another law; one we can't understand nor observe on a macroscopic level. So how did he figure it out? Like I said earlier, electrons orbit around the nucleus of an atom. Atoms do not allow electrons to be in between orbits. This is why electrons can only absorb certain colors, they can only absorb the light of colors that correspond to a difference between two valid orbits.
Once understood, quantum mechanics can be viewed quite simply. If you have come across the probability theory, even briefly, you may find that they are similar but quantum mechanics' probabilities can be negative.
Quantum does what?
We've scratched the surface on quantum mechanics and the scientists behind it, but what about quantum computers? We have studied the nature of quantum mechanics but in order to build a stable, functioning computer we must be able to control, in a sense, quantum mechanics to make it work in the way that would most benefit our cause. Thus far we have created artificial systems that abide by the laws but are well, man-made and don't exist in nature.
Quantum computers will have various useful purposes in the future. For example, they could send secret messages to in a more secure way. Another is the amount of information we can receive in smaller amount of time. Regular computers use 1's and 0's to code programs but quantum computers use both simultaneously. So if you were to have 50 1's and 0's you'd have an incredible amount of possible values, but a quantum computer practices superposition which allows it to be in multiple places at once, like a billion places at once when a regular computer can only be at one. This is quantum parallelism. So we have a billion results in a substantially smaller amount of time, but how do we access them without the rest dissapearing? To quote an article I read, "To solve this problem, one uses the second effect, quantum interference. Consider a process that can arrive at the same outcome in several different ways. In the non-quantum world, if there are two possible paths toward one result and each path is taken with a probability ¼, the overall probability of obtaining this result is ¼+¼= ½. Quantumly, the two paths can interfere, increasing the probability of success to 1."
Both quantum parallelism and quantum interference are used to balance this super computer and ensure its success. Quantum parallelism does large computations while interference combines the results into something plausible and makes sure the computer follows the laws of quantum mechanics.
To build a quantum computer we have found the most effective way would be to use ions. We can trap ions, line them up, and arrange them in intervals. We have successfully lined up 14 ions. This isn't the only way though, we could also use the electric current in super conductors but this is very difficult. Or we could use photons. Each process will take much time, effort, and research but the future of quantum computing and humanity's relation to it is just beginning.
More and more enthusiasts, programmers, and all types of scientists are exploring the future of quantum computing every day. There's still much to be discovered in the quantum mechanics realm and as time proceeds excitement grows. Hopefully one day quantum computers will be accessible in a safe and helpful way to benefit the public, but for now, gosh I love a mystery to solve. I can't wait for updates in the quantum world, keep an eye out for any news on my website, and clear skies my friends.