# What is Quantum Computer? How does it work?

From this precise moment it is foreseen that **the computers of the future will be quantum computers** , since the largest technology companies in the world such as Microsoft, Google, Intel or IBM are working on projects of this type, and even the latter has already launched quantum computer models quite successfully.

Quantum computing has the particularity of being able to process data at a speed that is currently unthinkable for current processor technology, however, **quantum computing is something that the average user is not going to be of much direct use to. **Quantum computing is not intended to improve current computers, or any of its components such as the CPU or the video card, and therefore we will not be able to take advantage of these discoveries to improve our handicap in any game.

Quantum computing is designed for other purposes, and it is very different from computing today, it is a **true change in the point of view of how devices process information and solve problems,** and although it is not yet a technology that may be in the hands of ordinary users, as we said, it will soon be among us taking care of everything we can’t see, like home banking, cloud computing and everything else.

That is why **quantum computing is so important for our future,** and it does not hurt to learn about it in order to be informed, which may seem complicated at first, but the truth is that knowing the **bases on which the technology was created Quantum and its objectives,** understanding its mode of operation and process will become a simple task, especially with all the data we have to offer you in this article.

**What are quantum technologies?**

As we know, during its evolution, Humanity was developing its technology and science based on its needs and on how it understood the behavior and functioning of the nature that surrounded it. As history passed, technology evolved and with it also opened a door to new challenges derived from those discoveries.

At this very point we are facing one of those doors, **whose key is quantum computing,** a technology that is based on the manipulation of the smallest elements of the physical world to form them, put them on track and make them do what we want. An incredibly complex task that, however, is already working for us, and evolving with each passing minute.

Many other different technologies derive from the quantum world **,** called **“Quantum Technologies”,** which are basically defined by having **quantum properties of a subatomic nature such as quantum superposition and quantum entanglement** as a basis. Among them quantum computing, the one that concerns us in this article.

In this sense, we must understand that the first ideas about quantum technologies occurred between the first years of the 20th century, more specifically between the years 1900 and 1930, when the studies carried out on some physical phenomena that were not yet fully understood gave space to a new perspective: **Quantum Mechanics.**

More specifically, **the origins of quantum mechanics date back to 1925,** when Edwin Schrödinger developed the wave equation, which describes the time evolution of a quantum particle.

In basic form, **this quantum mechanics describes what happens in the world of molecules, atoms and electrons,** and due to these studies and theories not only could these unknown phenomena be explained, but also a door was opened to a subatomic world that it was necessary to understand to take advantage.

Thanks to the fact that we managed to understand the functioning of this microscopic world of molecules, atoms and electrons through **Quantum Mechanics and the technologies derived** from it, it allowed us to have a much broader panorama than we used to have, and made it easier for us to improve The way of life of all Humanity, such as the transistor, a fundamental electronic component for the development of processors and microprocessors that allowed our devices to be smaller, stable and safer, was possible thanks to being able to understand how electrons behave in conductive and semiconductor materials.

Another more than clear example of how **quantum mechanics** is the origin of many of the technologies that we enjoy today is the Laser, which would not be possible without Albert Einstein laying the foundations of stimulated emission in 1917, using the **theory quantum radiation.**

Also as a good example of where quantum theories took us, we can name the SQUID rings, which were presented in 1967 and which are basically sensors that are capable of detecting even the magnetic field of our brain. These work based on the fact that **electric current is capable of flowing, without applying any type of voltage, between two superconductors at a short distance** , which refers us to magnetoencephalography and to various fields in health.

Today we are at a point **where quantum technologies are taking up more and more space,** eventually replacing old digital technologies and leaving them behind forever.

The **quantum technologies** are used in diverse and broad fields such as **quantum simulation** , communications, security, **quantum computing,** the main purpose of this article, the technology of the blockchain, quantum optics, quantum metrology, quantum clocks, quantum sensors, augmented reality and virtual reality, artificial intelligence, IOT, better known as the **“Internet of things”,** and in a myriad of less spectacular implementations but that will undoubtedly change the way we see things, such as autonomous vehicles, 3D printers, drones and others.

All these **technologies derived from quantum laws** were designed with the purpose of improving our quality of life, and at a certain point **quantum technologies such** as **quantum computing** are destined to combine, thus creating a world that not even in our wildest thoughts we could dream.

To learn more about **quantum technologies, it** does not hurt that we know about the **origin of quantum computing** , and thus be able to navigate this article in the most agile way possible, since later we will find much more information than to understand the everything, we will need to be clear about as many concepts as possible.

**Origin of quantum computing**

Arguably, the **foundations of quantum computing** that we know today were developed during the 1920s by Albert Einstein, Niels Bohr, Planck, Werner Heisenberg, Louis-Victor de Broglie, and others, to be finally announced and discussed in the Fifth Solvay Congress in 1927 by the most relevant scientists of the time.

Also at the same congress were Peter Debye, Irving Langmuir, Martin Knudsen, Auguste Piccard, Max Planck, William Lawrence Bragg, Emile Henriot, Paul Ehrenfest, Marie Curie, Hendrik Anthony Kramers, Edouard Herzen, Hendrik Antoon Lorentz, Théophile de Donder, Paul Adrien Maurice Dirac, Erwin Schrödinger, Arthur Holly Compton, Jules-Emile Verschaffelt, Paul Langevin, Charles-Eugène Guye, Wolfgang Pauli, Max Born, Charles Thomson Rees Wilson, Ralph Howard Fowler, Léon Brillouin and Owen Willans Richardson, the greatest scientists of those years.

Later Alan Turing would create his **“Turing Machine”,** basically a model to simulate the logic of any computer algorithm, that is to say that the Turing machine was not developed with the objective of providing a practical function. We mention this development because it is **fundamental in the history of quantum computing.**

Much later in time, precisely in 1981, Paul Benioff was the first to propose the idea of a quantum computer, **basically a Turing machine but that worked according to the statements of quantum mechanics. **A year later, Feynman argued that a quantum computer could be much faster than any other device so far. After that, the **first quantum algorithms** appeared in the 1990s, and with these algorithms, the first applications and computers capable of performing **quantum calculations.**

All this thanks to **understanding the universe of superposition** , a word that to fully understand its meaning, at least in the field of computers, we must first understand how a digital or standard computer works.

**Digital computers and quantum computers**

Digital computers, that is, today’s computers, including tablets, cell phones, PCs and other devices, as we know, work using so-called bits, basically a language of ones and zeros. This is true for both hardware and software. In other words, every time we give an order to a digital computer, **hundreds of thousands of strings of ones and zeros are created, combined, modified and destroyed in** order to carry out the task entrusted to it.

These bits are nothing other than states, which we can call **“1”** and **“0”,** and basically correspond to the absence or presence of electric current in the millions of transistors that make up a processor. With this operating mode, the so-called **“tunnel effect” is produced,** where the miniaturization of the components is the culprit that the power that can be reached is already on the edge of its possibilities.

This is due to the fact that the smaller, **we are talking about a nanometer scale,** which are the components, the smaller the sizes of the implementations of these processors will be, however, **the size of the electrons that circulate through them cannot be reduced,** creating the so-called tunnel effect, for which it was necessary to develop other types of computers, which made use of solutions that could cross this barrier. This is where **quantum laws** begin to come into play **.**

**Quantum evolution**

As we mentioned, the technology needed another approach to **face the barrier of the “tunnel effect”,** for which it began to explore and it was found that one of the most effective ways was to use the **known properties of quantum mechanics** , which already we are in a position to use and manipulate in our favor. These properties include **overlap** and **entanglement** . It should be noted that this moment is called the first quantum revolution.

The so-called **quantum superposition** is a characteristic that **quantum systems** have , which allows them to be in a combination of several states simultaneously. On the other hand, quantum entanglement occurs **when two or more quantum systems** interact with each other.

The combination of these two properties, **superposition** and **entanglement** , allow us to create states that are not the usual ones, that is, they are capable of displaying exotic properties, which opens a door to different technologies that are unknown to this day. .

All this happens thanks to the aforementioned **quantum characteristics** “superposition”, which describes how a particle can be in different states at the same time, and “entanglement”, which explains how a set of minimal entangled particles are united in their existence in a way such that although there are thousands of light years between them, the change of state of one of these particles will affect the rest immediately and without anything mediating between them.

**Second quantum revolution**

The so-called **second quantum revolution** is based on the possibility of creating and manipulating quantum systems individually, which allows us to **isolate and manipulate electrons or photons in** isolation to use them in a way that adapts to our objectives, controlling how and when they interact between they.

As mentioned above, digital computers use **“1”** and **“0”,** called **“bits”** ; On the other hand, in quantum computers the basic unit of information is the **“Qubit”** . These qubits are basically individual quantum units to which we can establish states of superposition or entanglement with other qubits, controlling the intensity with which they do so. The latter is impossible to do with current transistor technology, which makes the huge difference between the two systems.

**The quantum computer**

The **quantum computers** , as its name implies, take advantage of the quantum properties of certain elements such as superposition and entanglement to **execute algorithms quantum,** using the so – called qubits, we allow reaching capabilities much higher processing than anything seen up to now.

However, it **is wrong to think that quantum computers do the same as digital computers but much faster. **The true purpose of a quantum system like this is to solve operations through so-called quantum algorithms, which we will talk about later, much more efficiently. In other words, in order to have a quantum computer to play Minecraft, we will have to wait a long time.

To understand this, nothing better than an example. In this we need a digital computer to calculate the most viable route to reach any destination among 1000 alternatives. In this case, the digital computer will need to repeat the calculation process 1000 times to find the most direct route.

On the other hand, a quantum computer, thanks to the process called **“quantum parallelism”,** is capable of analyzing all the alternatives at the same time, saving a considerable amount of time. This capacity makes **quantum computers have such an important relevance in today’s world,** since if we get more computing power we can get more benefits.

In this sense, there are already some **solutions based on quantum computing** , especially in the field of scientific research, however there are some applications of quantum computers in the commercial market, such as those offered by IBM with its System One.

However, **the quantum computer** for the moment will not be able to replace digital computers, but they are two technologies that will complement each other and cooperate together for many years.

**What are quantum computers for?**

Computers stopped being dreams on paper years ago, **today there are quantum computers in operation** and most governments and high-tech companies are involved in the development of this type of technology, since they have more than demonstrated that Once installed at all levels, these quantum computers will revolutionize the way in which various sectors such as the economy, industry, research and business develop and grow, offering, thanks to the **great computing capacity of these** better and more sophisticated **quantum ****computers** services their customers.

In this sense, what quantum computers promise is to exceed the processing capacity of current computers in order to solve problems and situations that cannot be solved with digital computers. However, this is an extremely difficult task, since **a quantum computer is nothing like a computer as we users know,** and it poses significant challenges.

A **quantum computer** does not work in the same way as a **digital computer,** since it does not have any of the elements that we have become accustomed to using, that is, they do not have memory or hard disk. Basically quantum computing consists of *storing information in the so-called quantum states of matter and using quantum gate operations to carry out the process of this stored information.*

For this to happen we must **learn to program quantum interference. **In this sense, we must **develop the so-called quantum algorithms** that use the aforementioned peculiarities of entanglement and superposition, which will allow us to get the full **potential of these quantum computers** in order to solve very complex calculations that today are far from the scope of the digital computers, such as calculating the configuration of molecules with a large number of electrons, situations in which the algorithms of classical computing fail.

Although all kinds of tests are being carried out, and even as we mentioned above there are already **commercial quantum computers such as the IBM System One,** for the moment the full potential that this type of technology can achieve is ignored. However, what has been seen is enough for many companies to start investing in its research and development.

The areas of industry and research that have contributed the most to the **development of quantum technology** are, for example, the chemical industry for drugs and materials, oil companies for the development of new materials, the automotive industry for the development of new materials that allow improvement. productions and vehicles, the security and logistics industry, among many others.

Some of the technology companies researching quantum computers include *Microsoft, Alibaba, Tencent, Nokia, Airbus, HP, AT&T, Toshiba, Mitsubishi, SK Telecom, Thor, Lockheed Martin, Righetti, Biogen and Volkswagen.*

The fact is that **quantum computing** allows the development of artificial intelligence to be carried far beyond what we imagine, and in the not too distant future, everything will move through large AI centers, and the main players in the world economy they do not want to be left out of this technological revolution.

Some of the main **reasons why quantum computers are not yet a reality for all users,** are that in addition to being very difficult to develop, they are also very difficult to build, physically locate and program, and above all there is no budget that can encompass the **purchase of a quantum computer.**

That is why **quantum computers have a projected market niche located in the same place that supercomputers occupy today. S** i well as mentioned IBM already has on the market a quantum computer, as well as D-Wave and other companies, the fact is that this is only the tip of the iceberg, since experts indicate that the **first ****commercial computers quantum** of general use will appear in the market towards the third or fourth decade of the XXI century, with quantum computers that are capable of exceeding at least 1000 qubits.

**Bits and qubits**

As we have seen throughout this article, **the unit in which quantum computers calculate are qubits,** units that come from the **laws of quantum mechanics. **More technically speaking, these terms in English refer to **“quantum bit”,** which in Spanish means **“quantum bit”,** which is also shortened to **“Qubit”.**

We explained above that digital computers use the values of **“1”** and **“0”,** which represent two states, **“On”** or **“Off”, you** could say. On the other hand, **qubits can be able to use both values simultaneously,** something known as “superposition”, or even intermediate values. This allows quantum computers to process more information in the same time as a conventional computer. In quantum systems, the number of qubits tells us the number of states that can be in superposition.

In this sense, **two bits are capable of representing the four states: 00, 01, 10, or 11,** however, it can only take one of the four states. In qubit-based quantum systems, two qubits can also represent the four states 00, 01, 10, or 11, but **could** also **be able to take on all four states simultaneously.**

Since **the states of a qubit are governed by the laws of quantum mechanics** , there is no way to know its state until every measured qubit has been measured. For this reason, it is only possible to predict their states using probabilities.

Basically, the quantum states of a qubit can be represented in two ways: **Fundamental** | 0⟩ or the **Excited** state | 1⟩, which would be similar to the classical bits 0 and 1.

**How a quantum computer works**

One of the key conditions so that the **particles that act as qubits** can be read and written, is that they must be perfectly controlled and be stable long enough for both things to happen. This is because **the materials of which qubits are composed are still being studied,** and in order to control them, control devices based on superconducting materials and ion traps are used.

To **trap these ions,** these traps use optical fields or electromagnetic fields forming a kind of mesh, although it is also possible to use a combination of both. To interlace their spin states through their vibrations, the ions are pushed through the use of control lasers.

There are also other types of control mechanisms, but they are really very complex to design and put into operation, since their **circuits of superconducting materials** must be cooled to very low temperatures, almost to absolute zero, that is to say about −273.15 ° C. . Also, there should be no type of electrical resistance. Under these conditions it is almost impossible for the circulation of electrons to be exhausted. **To ****control the qubits, systems are used that allow the modification of the current flowing through the circuit.**

With these mechanisms it is possible to control a significant number of atoms, and they work much better than **devices based on ion traps. **Some of the technology companies that use this type of superconducting materials for the operation of their quantum computers are Google, Waves-D and IBM, among others.

Likewise, there are other **quantum computer manufacturing technologies,** based on semiconductor materials and solid-state components, however, these do not reach the necessary degree of perfection and stability. Studies are also being carried out with other types of quantum systems, such as **quantum optical systems,** which use optical traps to trap photons, using light waves that control these photons.

**Quantum computer programming languages**

Although **quantum languages** have existed before the **first quantum computers were** created , the truth is that these languages were used to simulate the behavior of quantum algorithms in digital computers. This fact changed when the first quantum computers began to be built, after which a race began by companies and research institutes first to develop a programming language for their own devices and then to try to standardize them for all other quantum computers. However, it is a winding path, and without the collaboration of all the actors it is difficult to carry out.

This fact has motivated the **development of** open source **quantum programming languages** , that is to say that it is possible to contribute to the improvement and extension of these languages and then use it in their own developments, which has also led to the search for the so-called **” universal quantum programming language ”,** which will allow a much faster and more focused development.

Currently, there are several quantum programming languages such as **QCL (Quantum Computing Language), Q # or OpenQASM (Open Quantum Assembly Language),** and it is also possible to program basic quantum computing circuits using JavaScript or Python, but at the same time New programming languages are also being developed, which aim to solve all the problems that can be found when programming a quantum computer.

**Quantum algorithms**

In terms of quantum computing, **a quantum algorithm is basically an algorithm that runs on a realistic model of quantum calculation,** which is the most widely used model of quantum computing circuit.

As we know, a classical algorithm, that is, it is not a quantum algorithm, it is a finite sequence of instructions, or a procedure used to solve a certain problem step by step.

In the case of **quantum algorithms** , these are also step-by-step procedures, where each of the steps can be performed on a quantum computer. Although **all classical algorithms can also be performed in a quantum computer,** the term quantum algorithm is used more specifically in quantum computing when it is necessary to include its own characteristics such as superposition or entanglement.

Although in theory quantum algorithms are much more capable in terms of information processing than **classical algorithms,** the truth is that most of this capacity is dissipated in measurements, although the information obtained is always much more useful than that obtained **by a classical algorithm.**

**Most popular quantum algorithms**

One of the most important properties of quantum computing is the so-called **“implicit parallelism”,** which allows an exponential number of basic transformations to be processed **through a linear number of qubits in a quantum system. **At this point there are various quantum algorithms that allow us to take advantage of this advantage, which we will mention below.

*Deutsch-Jozsa algorithm, or “how to look at both sides of the coin at the same time.”*

The **Deutsch-Jozsa algorithm** was developed and proposed by David Deutsch and Richard Jozsa in 1992 and was further improved by Richard Cleve, Artur Ekert, Chiara Macchiavello, and Michele Mosca, more precisely in 1998.

The basic function of this quantum algorithm is to determine if a black box type function is of the **“constant”** or **“balanced” type. **It should be noted that this quantum algorithm does not have too many practical applications, however it is used as one of the best examples of a quantum algorithm that has been shown to be faster than any other possible deterministic classical algorithm.

*Shor’s algorithm, or “how to factor in polynomial time”.*

The **Shor ‘s algorithm,** developed and proposed by Peter Shor in 1995 is closely related to modular arithmetic, and is also the best known quantum algorithm when **talking about security and cryptography.**

Peter Shor also developed **quantum error correction,** and it was one of the first methods to ensure error-proof quantum computing. This was a more than important advance, since due to its quantum nature, the error corrections of digital computing cannot be applied to the quantum field.

*Grover’s algorithm, or “how to find a needle in a haystack.”*

The **algorithm developed by Lov Grover** , and published in 1996, was able to show that a practical utility problem could be solved more quickly with a quantum algorithm than with the best available classical algorithm.

**The State of Quantum Computing Today**

Although **quantum computing** is not a field in which there are too many twists or turns or evolves very quickly, the truth is that each day that passes small steps are taken, which over time will translate into a technology of which we are not going to to be able to detach ourselves.

Real quantum computing, that is, that of the devices that are operating and generating expectations, has been with us for a few years, generally in research and development fields, but nevertheless it is a technology that everyone wants to advance and expand until the only one corner, for this reason companies make available to users tools that allow them to generate their own projects and **interact first-hand with quantum computers.**

One of these projects is the so-called **IBM Quantum Experience,** a quantum computer simulator, which since 2016 allows any user with a simple internet connection, and of course the necessary knowledge, to design and run their own quantum circuits.

Later, precisely in the year 2019 again, IBM reaches the top of the podium, launching the world’s first quantum computer for commercial use, **the Q System One,** a quantum system that uses 20 qubits.

That same year, in October, **Google announced that it had achieved quantum supremacy** , which means that it was able to develop and build a device with which it is possible to solve problems that no computer or digital supercomputer could.

**The future of quantum computing**

There is no doubt that **quantum computers are the future of computer science** , and in a few years we will see advances in them that will really surprise us.

In this sense, we can think that **digital computing also has a bright future** ahead, since there is talk of futuristic technologies and construction materials that promise progress until now unthinkable, but such progress will only increase the capacity of digital computing in a way line, **contrary to quantum computing, whose growth is exponential.**

Despite its complexity of concept, **quantum computing does not require sophisticated technologies for its manufacture or implementation,** an advantage that classical digital computing does not have, since its development depends almost exclusively on other technologies that are also under development. , such as nanotechnology and other elements that are still being studied.

At present, **within the field of study of quantum computing, there** is talk of producing more qubit capacity through the use of caffeine, hydrogen or chloroform molecules, very far from the concept of classical digital computing, with components such as storage units. , processor, video, audio and other cards made of silicon, plastic and metal.

When scientists in the late 1940s dreamed of one day shrinking the size of **those early computers** to run on just a couple thousand vacuum tubes, they couldn’t even imagine that the silicon in microprocessors could go as far as to allow us to create a device called a smartphone.

Nowadays things are a little different, knowledge is much greater, and the tools we have to achieve the objectives we set for ourselves are many and very powerful. This means that **quantum computers in the not too distant future may not be the way we envision them,** large futuristic-looking surfaces, and may not even have a recognizable computer shape.

This is due to the constant **advances in quantum computing,** with hundreds of scientific papers focused on taking it to a higher level every day, and that contemplate different aspects such as the **development of qubits, quantum algorithms, applications of quantum computing** and many other aspects. However, the scientific papers that most attract the attention of all types of users are those that talk about the practical application of quantum computing and the **modeling of physical systems.**

All these studies tell us that quantum computing in just 25 years will achieve a processing capacity and speed that we still have no idea where it will take us. Many even assure that quantum computing, when it makes contact with artificial intelligence and the so-called Internet of things , reaches an incredible level, being able to learn by itself at an astonishing speed, with which it can be in a position to make decisions that even today they were the authority of other areas, with all the advantages and dangers that this entails.