Quantum computer

Have you heard of the quantum computer? A computer that would use photons instead of electrons as the medium of computation. Do you know what it is, really? Would you like to know? I knew you would.

There is a phenomenon in quantum physics called entanglement. It means that two particles that originated from the same quantum phenomenon, share a common state (typically the particle spin), and when you measure the state of the other, the other particle's state is immediately known too, even though both of the particle states were unknown just before measurement. So the particle states are unknown, but still somehow coupled.

This extraordinary phenomenon is very uncomfortable, as it seems to transfer information (the state of the particle) faster than speed of light. And as Einstein stated, this should not happen.

Entanglement has one very interesting theory to explain it: the parallel universe theory. Every time a pair of entangled particles are formed, the universe splits into two parallel alternatives. One of them contains state AB and the other BA. Both of these universes exist at the same time, without anyone knowing. When first particle is measured, one of the parallel universes realizes, and the other disappears. Or does it? What happens to it?

Quantum computer was designed as a test whether this kind of parallel universes actually exist. Sure, it would be nice to know if such things exist, as everything you do is based on quantum physics, including decisions you do inside your brain! Think about it. In that parallel universe you decided to finish your studies and ditch your boyfriend. That would make a great romantic comedy. Oh, it's been done? But I'm sure you didn't realize the movie is about quantum computers.

Anyway. the test would work OK with a 1-bit computer. But the scientists found something funny. If you add more bits, which are also entangled, let's say 32 bits, the computer will contain 4 billion parallel universes (alternative states) that means all of those possibilities exist simultaneously. This is where the scientists got really interested. Such computer could perform incredibly well in tasks where parallel calculation is required.

It is sometimes quoted that to decrypt AES-256 it will take all the computers ever built, and a time longer than the age of the universe. But imagine if all the possibilities could be tested simultaneously. The quantum computer's state would divide into an infinite number of parallel states which each make make a guess of the pattern. One of these parallel routines hit it right, and the entire construction will then collapse to that state.

Such computer will be extremely hard to construct, for a number of reasons. To maintain a quantum state and keep it from collapsing, the particle should be completely isolated from its environment. And this means total isolation. No warmth, no hitting other particles, no magnetic fields or other fields, nothing - at least in theory. Having said that, I should also mention this. First computer utilizing quantum calculation is on market, providing a variety of programming environments such as C++, Java, Python, SQL, and MATLAB. Extremely cool.

So this is the situation now. For some unknown reason, sponsors like military are more interested in funding projects that develop decrypting computers than scientists that study the essence of the universe. The original purpose of quantum computers has silently faded in background, and the quantum computer has shifted from science into engineering. The nature of entanglement remains still to be explained. Maybe we will never know if parallel universes exist or not. At least I don't believe there is a python script in the new D-Wave computer to tell us that.