Fri. Jan 17th, 2020 # How a quantum computer works

Since the first computer appeared, the world ceased to be the same. Problems of complex characteristics could be solved much more quickly and easily and this was what caused that each time the computer science was evolving at a monstrous pace.

Since the first computer appeared, the world ceased to be the same. Problems of complex characteristics could be solved much more quickly and easily and this was what caused that each time the computer science was evolving at a monstrous pace.

But as the problems were resolved faster, new problems arose and much harder than the previous ones. While our computers are capable of solving mathematical operations and many tasks in milliseconds or in the worst case, seconds or minutes, there are other mathematical operations and "infinite calculations" that are not able to solve in a certain time, in fact It could take millions of years.

This is how the idea of quantum computer. A machine capable of calculating very high complexity and processing large amounts of data in a short time.

To understand this concept well, it is necessary to understand what we usually use.

Your computer can only interpret the information in two states: zero or one (off or on, respectively). These are called bits, which are nothing more than quantities of voltages.

Everything that is done on a computer is transcribed to this system by transistors: “small boxes” that can store energy and release it when necessary.

In addition there are circuits called logic gates - based on mathematical logic - that measure the state of the boxes and store energy in new boxes depending on what they regulate.

For example, the door OR measure if there is electricity in two boxes, and only if there is electricity in any of them saves electricity in another box.

V = True (1).

F = False (0).

V OR F = V (1)

V OR V = V (1)

F OR F = F (0)

Well, this is a minimal part of what is executed every time we perform an action through programs and apps. And yes, this system makes the speed at which a computer can process the information is linear to the amount of bits it has, depends on the hardware and by default has a limit.

Well, then we understood more or less how it works, now comes the other part, quantum computing.

The bits of quantum computing are called qubits. Like a bit, a qubit represents a basic unit of information, but a unit of quantum information that is governed by the norms of quantum physics and therefore the qubit can be 0 or 1, or it can also be 0 and 1 at the same time.

### We give an example:

Suppose we have 4 information strings of 4 bits each and in a search engine we need to know what the correct string is.

• 0100
• 1010
• 1101
• 0101

In this case the correct one will be 1101, so what conventional computers do is search one by one until you find the right one:

¿1101 == 0100? False. Next.

¿1101 == 1010? False. Next.

¿1101 == 1101? True. Finalize.

That is the way to operate only in milliseconds, even so, this is slow for large amounts of data.

The quantum computer as we said uses qubits and this same search would work as follows:

¿1101 == 0100, 1010, 1101, 0101? True and false.

How? Is it true and false at the same time?

Yes, it is true and false at the same time and to solve this Grover's algorithm is used, discarding the wrong answers. That is, the quantum computer verifies all the answers at the same time and if they are not correct, then it excludes them, making the search much faster.

But beware, this does not mean that these machines can solve puzzles and find solutions immediately but if it reduces noticeably the time compared to current computers, what, as we said, they can take millions of years to find a solution, quantum ... Just a couple of seconds.

Great, isn't it?

Even so it is complicated to understand, even for the same ones who are investigating them.

IBM currently offers an online service to experiment with its quantum computer called: IBM Q Experience, the problem is that you must handle the subject to understand its operation.

This is his page: IBM Q Experience.

Google also opted for this issue and together with NASA they acquired D-Wave Systems, company responsible for conducting deeper research on quantum computing.

Without a doubt, these machines will rewrite the computer science as we know it today and will achieve things that we don't even imagine.