What is Quantum Computer and How Does It Work

Do you want to know what is Quantum computer and how does Quantum computer work? You are at the right spot to know the answer of this question.

The quantum computer is already a reality, although the existing ones are still in an early stage of development of this promising new paradigm.

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These types of computers are unknown to many, and are based on quantum physics, which for someone             is almost like magic compared to classical physics. Here you can learn what these strange machines are and how they work, among other things.

Classical Physics vs Quantum Physics

There are some similarities between quantum mechanics or quantum physics and classical mechanics or classical physics, and also some differences. But what exactly are they?

• Classical Physics

It is the study of macroscopic bodies, such as statics, movement, etc. And it consists of three main branches, such as Lagragian, Newtonian and Hamiltonian, with different mathematical methods to study the phenomena.

• Quantum Physics

Studies microscopic bodies, and comes from the term “quantum” and comes from the fact that the energy of a system is quantized.

The photon theory is one of the cornerstones of this mechanics, stating that light is in the form of wave packets. Werner Heisenberg, Max Plank and Albert Einstein are some of the scientists involved in this mechanics.

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Also, you should know that this physics is divided into two categories, the first with non-relativistic bodies when studying the quantum mechanics of particles with speeds relatively small compared to the speed of light.

And the other is the quantum relativistic, which studies particles that move at speeds similar to that of light.

In addition to what was said above, there are some notable differences between the two, which are:

• Quantum mechanics applies to subatomic bodies while classical mechanics only applies to macroscopic bodies.
• Quantum mechanics can be applied to macroscopic bodies but classical mechanics cannot be applied to subatomic systems.
• Classical mechanics can be considered as a special case of quantum mechanics.
• Classical mechanics is a fully developed field while quantum mechanics is still a developing field.
• In classical mechanics, most quantum effects, such as energy quantization and the uncertainty principle, are not useful.

Quantum physics gives rise to truly strange phenomena, which now seem “magic” or almost paranormal to us, but which this physics can demonstrate.

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Surely you have heard more than once about the famous Schrodinger’s cat, which tries to explain part of this quantum physics:

What is a Qubit or Quantum bit?

A binary bit can take two different states, 0 or low level, and 1 or high level. It is the basic information unit of a classical computer.

On the other hand, a qubit or quantum bit is the basic information unit of a quantum computer, but in this case it can not only have the two states mentioned above, but it can also have several superimposed states at the same time (like the famous cat).

The qubit can represent a 0, a 1, or any proportion of 0 and 1 in the superposition of both states, as a certain probability of being a 0 or a 1. It is precisely this capacity that allows these machines to have capabilities of processing far superior to classical computers.

On the other hand, the amount of information that a qubit can represent increases exponentially. For example, 5 qubits can represent more information than 2^5 in the classical system.

And, to give you an idea, calculating the prime factors of a 2048-bit number could take millions of years in a classical computer, while in a quantum computer it would take a few minutes.

Also, it is important to note that there are many ways to represent qubits. While in the classical ones it is done through digital circuits, in the quantum ones it can be done through trapped ions, photons, artificial or real atoms, quasip articles, etc.

Some of them need temperatures close to absolute zero (-273ºC) and hence they have such a strange appearance due to the complex cooling system used.

Finally, some people think that it is simply a matter of adding more and more qubits to a quantum computer, and that the companies that get more of these qubits are the ones that are ahead.

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But the truth is that this is not the case, it is necessary to ensure that these qubits are stable, and the most advanced chips are those with better qualities, not with greater quantities. Otherwise, other qubits will have to be used as a correction system.

How does a Quantum Computer Work?

In a quantum computer, the laws that apply to be used by the classics no longer work in this new paradigm. Digital logic (from the classic logic gates AND, OR, NOT, NAND, NOR, XNOR, NOT, etc., to quantum gates such as CNOT, Pauli, Toffoli, SWAP, Hadamard, etc.), the form of schedule, etc., is no longer valid.

Everything changes. In fact, these experimental computers are mere calculation tools, like a server connected to a classic computer as a client. It is on the classical computer that the software actually runs.

To understand in a simple way how a quantum computer works and where its power comes from, it is necessary to understand that a one qubit can represent a zero, a one, a superposition of both values ​​at the same time, or a simultaneous superposition of all the qubits combined. .

For example, with 2 qubits the values ​​00, 01, 10, 11 can be represented at the same time. In other words, with only 2 qubits it is possible to represent what would be needed much more classical bits to represent and more CPU instructions to process them.

On the other hand, there is quantum parallelism due to entanglement, which is when the qubits have become entangled (in correlation) and can be manipulated to do exactly the same operation in parallel on all of them. Hence the great potential of this paradigm

In my opinion, quantum computers will not reach in the common society in near future, there will only be QaaS solutions to use as cloud services for companies, but we will continue to use classic devices for decades. What do you think?