Unlike conventional computers which by their nature perform one task at a time, quantum computers’ strong ace will be that they will be able to perform an unimaginable large amount of computational tasks in parallel at each time cycle of their operation; this technological knack is to be made possible by quantum mechanics’ strange laws which govern each and every element of our subatomic world.

Imagine, at your fingers, a computing power so potent that is capable of doing as much operations in a second as there are particles in our observable universe. Leaving aside some of its apparently “blunt” applications like cracking all the cryptographic codes invented so far, searching and instantly finding elements from databases so big that wouldn’t fit all the servers on the internet, factorizing numbers so large that no network of present-day supercomputers could ever have the chance at succeeding in our lifetimes, imagine how this could give us the power to build all of our future, but highly advanced and unimplementable on today’s computers, artificial intelligence systems. With the help of quantum computers we could build super brains, simulate complex molecule interactions that are completely intractable on present day supercomputers, find out the secrets to unlimited resources, and maybe discover the ultimate secrets of reality.

The parallelism I’m talking about is not achieved by any advancement in parallel computing of the currently available Turing machine systems, but by the property of every subatomic particle to find itself in multiple places at the same time. No matter how weird this might seem, parallel universes have long stopped to be the topic of science fiction novels. The components of a quantum computer manage to compute different tasks in an infinite number of parallel worlds and them combine the results from all those computations into one result ready to be made available to the output register located in the quantum computer’s electronic components that are of course constrained to our set of universes.

So how do we build them? Unlike a normal Turing machine that uses bits, that is, electrical circuits that can be put into two different electrical states, 0 and 1, albeit only one at a time, quantum computers will have to be build using Qubits. The difference between a Qubit and a bit is that the former one can store the value 0, or 1, or any combination of the two values at the same time, whilst a bit can only memorize a single value, 1 or 0, at the same time. Let me clarify this! Qubits can have 76% the value 1 and 24% the value 0, or 43.23% the value 0 and 56.77% the value 1, all at the same time. And you can dream of any other combination. This translates to : in 76% of the parallel universes belonging to the Multiverse the Qubit which I’ve exemplified earlier will poses the value 1 and in the rest of 24% it will poses the value 0. In the other example the Qubit will poses the value 0 in 43.23% of the parallel universes and in the other 56.77% it will poses the value 1. That’s a lot of parallel computing considering the total number of parallel universes calculated to be possibly perceivable by an observer lies around the figure of 10^10^16 universes (source).

What’s all this clap-trap about parallel universes and the multiverse? Quantum mechanics, the field of physics that deals with sub-atomic particles has solved and clarified some of our most mysterious experimental data that even Einstein couldn’t get the grips with. The interactions between all subatomic particles can well be explained and predicted with an accuracy worthy of envy by using the well worked mathematical model of Quantum Mechanics. But, although we can predict and calculate the subatomic world with very delicate precision, paradoxically, we do not understand why subatomic particles behave the way they do. As renowned quantum physicist Richard Feynman said : “If you think you understand quantum mechanics, you don’t understand quantum mechanics“. And why is that? It’s because atoms, electrons, protons, and all the rest behave in strange ways; they can be in multiple places at the same time; they sometimes behave like particles, sometimes like waves; they can travel back in time and even be connected one with another in ways that defy classical physics’ logic. Many explanations exist on the scientific highway as to why the quantum world behaves the way it does, but the most widely known, the Many Worlds Interpretation (MWI, Parallel Universes , Multiverse) first introduced by physicist Hugh Everett is converting with an ever increasing rate physicists from all kinds of fields. If you read Russell Standish’s The Theory of Nothing you can find that in a survey done by David Raub on quantum mechanics experts and cosmologists 58% of them believed that the MWI is true.

So, in order to build a quantum computer we must have bits that can find themselves in multiple universes at the same time and these are called, as we’ve stated earlier, Qubits. The fact that they must be made to work together in order to show their prowess, just like normal bits do, is a real impediment because quantum systems are easily vulnerable to the outside world; their small size and the risk of interference with other particles gives a real challenge to the experimentalists in this field.

Practically the challenge is to build a set of isolated-from-the-outside-world qubits, which are all interconnected with one another through what we call Entanglement. Unlike bit computing systems, which are relatively easy to put together and to integrate with one another because they are very large so they are immune to interference from other particles therefore they can be easily manipulated through classical physics methods, qubit quantum systems are very hard to make practical. Qubit systems must be read, written, and protected from alien particles all at the same time without disturbing the already established quantum entangled system. Entanglement, or “spooky action at a distance” is one of the strangest phenomenon that governs the quantum world. For example, when two particles are entangled, modifying a certain quantum property belonging to one of the two particles will also instantaneously modify the same property belonging to the other particle no mater the distance between the two; to translate this into quantum computing terms, measuring a certain property of a certain particle will instantaneously give you information about the property of the other entangled particle. Entangling a sufficient number of qubits (ions, electrons, photons, superconducting devices – solid-state qubits), and keeping them entangled and isolated from all the outside world an adequate amount of time is the main challenge that lies ahead in building the quantum computer.

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