Just about the complicated stuff: what a quantum computer is and why it is needed. What is a quantum computer

According to experts, very soon, in 10 years, microcircuits in computers will reach atomic measurements. It seems logical that the era of quantum computers is coming, with the help of which speed computing systems may increase by several orders of magnitude.

The idea of ​​quantum computers is relatively new: in 1981, Paul Benioff first theoretically described the principles of operation of a quantum Turing machine.

In the 1930s, Alan Turing first described a theoretical device that was endless tape divided into small cells. Each cell can contain the character 1 or 0, or remains empty.

The control device moves along the tape, reading characters and writing new ones. From a set of such symbols a program is compiled that the machine must execute.

In the quantum Turing machine proposed by Benioff, the operating principles remain the same, with the difference that both the tape and the control device are in a quantum state.

This means that the symbols on the tape can be not only 0 and 1, but also superpositions of both numbers, i.e. 0 and 1 at the same time. Thus, if a classical Turing machine is capable of performing only one calculation at a time, then a quantum one performs several calculations in parallel.

Today's computers work on the same principle as normal Turing machines - with bits that are in one of two states: 0 or 1. Quantum computers have no such restrictions: the information in them is encrypted in quantum bits (qubits), which can contain superposition of both states.

Working on part of the D-Wave quantum computer

©D-Wave Systems

Physical systems that implement qubits can be atoms, ions, photons or electrons that have two quantum states. In fact, if you make elementary particles information carriers, you can use them to build computer memory and new generation processors.

Thanks to the superposition of qubits, quantum computers are inherently designed to perform parallel calculations. This parallelism, according to physicist David Deutsch, allows quantum computers to perform millions of calculations simultaneously, while modern processors work with only one.

A 30-qubit quantum computer will be equal in power to a supercomputer operating at 10 teraflops (trillion operations per second). Power of modern desktop computers measured in just gigaflops (billion operations per second).

Another important quantum mechanical phenomenon that may be involved in quantum computers is called “entanglement.” The main problem with reading information from quantum particles is that during the measurement process they can change their state in a completely unpredictable way.

In fact, if we read information from a qubit in a superposition state, we will only get 0 or 1, but never both numbers at the same time. This means that instead of a quantum one, we will be dealing with a normal classical computer.

To solve this problem, scientists must use measurements that do not destroy the quantum system. Quantum entanglement provides a potential solution.

In quantum physics, if you apply an external force to two atoms, they can be "entangled" together in such a way that one of the atoms has the properties of the other. This, in turn, will lead to the fact that, for example, when measuring the spin of one atom, its “entangled” twin will immediately take the opposite spin.

This property of quantum particles allows physicists to know the value of a qubit without measuring it directly.

One day, quantum computers could replace silicon chips, just as transistors replaced vacuum tubes. However modern technologies do not yet allow the construction of full-fledged quantum computers.

Assembly of the D-Wave Two quantum computer processor

©D-Wave Systems

However, every year, researchers announce new advances in the field of quantum technology, and hope that one day quantum computers will be able to surpass conventional ones continues to grow stronger.

1998

Researchers from the Massachusetts Institute of Technology have succeeded for the first time in distributing one qubit between three nuclear spins in each molecule of liquid alanine or trichloroethylene molecule. This distribution made it possible to use “entanglement” for non-destructive analysis of quantum information.

2000

In March, scientists at Los Alamos National Laboratory announced the creation of a 7-qubit quantum computer in a single drop of liquid.

2001

Demonstration of the calculation of the Shor algorithm by specialists from IBM and Stanford University on a 7-qubit quantum computer.

2005

The Institute of Quantum Optics and Quantum Information at the University of Innsbruck was the first to create a qubit (a combination of 8 qubits) using ion traps.

2007

Canadian company D-Wave has demonstrated the first 16-qubit quantum computer capable of solving a range of problems and puzzles, such as Sudoku.

Since 2011, D-Wave has offered the D-Wave One quantum computer for $11 million with a 128-qubit chipset that performs only one task - discrete optimization.

Humanity, like 60 years ago, is again on the verge of a major breakthrough in the field of computing technology. Very soon, quantum computers will replace today's computing machines.

How far has the progress come?

Back in 1965, Gordon Moore said that in a year the number of transistors that fit on a silicon microchip doubles. This rate of progress has slowed recently, and doubling occurs less frequently - once every two years. Even this pace will allow transistors to reach the size of an atom in the near future. Next is a line that cannot be crossed. From the point of view of the physical structure of the transistor, it cannot in any way be smaller than atomic quantities. Increasing the chip size does not solve the problem. The operation of transistors is associated with the release of thermal energy, and processors need a high-quality cooling system. Multi-core architecture also does not solve the issue of further growth. Reaching the peak in the development of modern processor technology will happen soon.
Developers came to understand this problem at a time when users were just beginning to have personal computers. In 1980, one of the founders of quantum information science, Soviet professor Yuri Manin, formulated the idea of ​​quantum computing. A year later, Richard Feyman proposed the first model of a computer with a quantum processor. The theoretical basis of what quantum computers should look like was formulated by Paul Benioff.

How a quantum computer works

To understand how the new processor works, you must have at least a superficial knowledge of the principles of quantum mechanics. There is no point in giving mathematical layouts and formulas here. It is enough for the average person to become familiar with the three distinctive features of quantum mechanics:

• The state or position of a particle is determined only with some degree of probability.
• If a particle can have several states, then it is in all possible states at once. This is the principle of superposition.
• The process of measuring the state of a particle leads to the disappearance of superposition. It is characteristic that the knowledge about the state of the particle obtained by the measurement differs from the real state of the particle before the measurements.

From the point of view of common sense - complete nonsense. In our ordinary world, these principles can be represented as follows: the door to the room is closed, and at the same time open. Closed and open at the same time.

This is the striking difference between calculations. A conventional processor operates in binary code. Computer bits can only be in one state - have a logical value of 0 or 1. Quantum computers operate with qubits, which can have a logical value of 0, 1, 0 and 1 at once. For solving certain problems, they will have a multimillion-dollar advantage over traditional computing machines. Today there are already dozens of descriptions of work algorithms. Programmers create a special program code, which can work according to new principles of calculations.

Where will the new computer be used?

A new approach to the computing process allows you to work with huge amounts of data and perform instant computational operations. With the advent of the first computers, some people, including government officials, had great skepticism regarding their use in the national economy. There are still people today who are full of doubts about the importance of computers of a fundamentally new generation. Very for a long time Tech journals refused to publish articles on quantum computing, considering the field a mere scam to fool investors.

A new method of computing will create the preconditions for grandiose scientific discoveries in all industries. Medicine will solve many problematic issues, of which quite a lot have accumulated recently. It will become possible to diagnose cancer at an earlier stage of the disease than now. The chemical industry will be able to synthesize products with unique properties.

A breakthrough in astronautics will not be long in coming. Flights to other planets will become as commonplace as daily trips around the city. The potential that lies in quantum computing will certainly transform our planet beyond recognition.

Another distinctive feature that quantum computers have is the ability of quantum computing to quickly find required code or cipher. An ordinary computer performs a mathematical optimization solution sequentially, trying one option after another. The quantum competitor works with the entire array of data at once, choosing the most suitable options in an unprecedentedly short time. Bank transactions will be decrypted in the blink of an eye, which is inaccessible to modern computers.

However, the banking sector need not worry - its secret will be saved by the quantum encryption method with a measurement paradox. When you try to open the code, the transmitted signal will be distorted. The information received will not make any sense. Secret services, for whom espionage is a common practice, are interested in the possibilities of quantum computing.

Design difficulties

The difficulty lies in creating conditions under which a quantum bit can remain in a state of superposition indefinitely.

Each qubit is a microprocessor that operates on the principles of superconductivity and the laws of quantum mechanics.

A number of unique environmental conditions are created around the microscopic elements of a logic machine:

• temperature 0.02 degrees Kelvin (-269.98 Celsius);
• protection system against magnetic and electrical radiation (reduces the impact of these factors by 50 thousand times);
• heat removal and vibration damping system;
• air pressure below atmospheric pressure 100 billion times.

A slight deviation in the environment causes the qubits to instantly lose their superposition state, resulting in malfunction.

Ahead of the rest of the planet

All of the above could be attributed to the creativity of the fevered mind of a writer of science fiction stories if Google, together with NASA, had not purchased a D-Wave quantum computer last year from a Canadian research corporation, the processor of which contains 512 qubits.

With its help, the leader in the computer technology market will solve machine learning issues in sorting and analyzing large amounts of data.

Snowden, who left the United States, also made an important revealing statement - the NSA also plans to develop its own quantum computer.

2014 - the beginning of the era of D-Wave systems

Successful Canadian athlete Geordie Rose, after a deal with Google and NASA, began building a 1000-qubit processor. The future model will exceed the first commercial prototype by at least 300 thousand times in speed and volume of calculations. The quantum computer, the photo of which is located below, is the world's first commercial option in principle new technology calculations.

He was prompted to engage in scientific development by his acquaintance at the university with the works of Colin Williams on quantum computing. It must be said that Williams today works at Rose's corporation as a business project manager.

Breakthrough or scientific hoax

Rose himself does not fully know what quantum computers are. In ten years, his team has gone from creating a 2-qubit processor to today's first commercial brainchild.

From the very beginning of his research, Rose sought to create a processor with a minimum number of qubits of 1 thousand. And he definitely had to have a commercial option - in order to sell and make money.

Many, knowing Rose's obsession and commercial acumen, are trying to accuse him of forgery. Allegedly, the most ordinary processor is passed off as quantum. This is also facilitated by the fact that the new technology exhibits phenomenal performance when performing certain types of calculations. Otherwise, it behaves like a completely ordinary computer, only very expensive.

When will they appear

There's not long to wait. A research group organized by the joint purchasers of the prototype will report on the results of the research on D-Wave in the near future.
Perhaps the time is coming soon in which quantum computers will revolutionize our understanding of the world around us. And all of humanity at this moment will reach a higher level of its evolution.

Such machines are simply necessary now in any field: medicine, aviation, space exploration. Currently, computers are being developed based on quantum physics and computing technologies. The basics of such a computing device are not yet available ordinary users and are accepted as something incomprehensible. After all, not everyone is familiar with the photonic properties of elementary particles and atoms. To understand at least a little how this computer works, you need to know and understand the elementary principles of quantum mechanics. For the most part, this coherent computer is being developed for NASA.

A conventional machine performs operations using classical bits, which can take the values ​​0 or 1. On the other hand, a photonic computing machine uses coherent bits or qubits. They can take on the values ​​1 and 0 at the same time. This is what gives such computer technology their superior computing power. There are several types of computational objects that can be used as qubits.

1. Nucleus of an atom.
2. Electron.

All electrons have a magnetic field, as a rule, they look like small magnets and this property is called spin. If you place them in a magnetic field, they will adjust to it in the same way that a compass needle does. This is the lowest energy position, so we can call it zero or low spin. But it is possible to redirect the electron to the “one” state or to the top spin. But this requires energy. If you remove the glass from the compass, you can redirect the arrow in a different direction, but this requires force.

There are two accessories: low and high spin, which correspond to the classic 1 and 0 respectively. But the fact is that photonic objects can be in two positions at the same time. When spin is measured, it will be either up or down. But before measurement, the electron will exist in a so-called quantum superposition, in which these coefficients indicate the relative probability of the electron being in one state or another.

It's quite difficult to imagine how this gives coherence machines their incredible computational power without considering the interaction of two qubits. There are now four possible states for these electrons. In a typical two-bit example, only two bits of information are needed. So two qubit contains four types of information. This means that you need to know four numbers to know the position of the system. And if you take three spins, you get eight different positions, and in typical version three bits will be needed. It turns out that the amount of information contained in N qubits is equal to 2N standard bits. The exponential function says that if, for example, there are 300 qubits, then you will have to create crazy-complex superpositions where all 300 qubits will be interconnected. Then we get 2300 classical bits, which is equal to the number of particles in the entire universe. It follows that it is necessary to create a logical sequence that will make it possible to obtain a calculation result that can be measured. That is, consisting only of standard accessories. It turns out that a coherent machine is not a replacement for conventional ones. They are only faster in calculations where it is possible to use all available superpositions. And if you just want to watch a high-quality video, chat on the Internet or write an article for work, a photon computer will not give you any priorities.

This video describes the process of a quantum computer.

In simple terms, the coherent system is designed not for the speed of calculation, but for the required quantity to achieve results, which will occur in a minimum unit of time.

Job classical computer based on information processing using silicon chips and transistors. They use binary code, which in turn consists of ones and zeros. A coherent machine operates on the basis of superposition. Instead of bits, qubits are used. This allows you to not only quickly, but also make calculations as accurately as possible.

What will be the most powerful photon computing system? For example, if photon computer has a thirty-qubit system, its power will be 10 trillion computational operations per second. Currently, the most powerful two-bit computer counts one billion operations per second.

A large group of scientists from different countries has developed a plan according to which the dimensions of the photonic apparatus will be close to the dimensions of a football field. He will be the most powerful in the world. This will be a kind of structure made of modules, which is placed in a vacuum. The inside of each module is ionized electric fields. It is with their help that certain parts of the circuit will be formed that will perform simple logical actions. An example of such photonic computing technology is being developed at the University of Sussex in England. Estimated cost for at the moment more than 130 million dollars.

Ten years ago, D-Wave introduced the world's first coherent computer, which consists of 16 qubits. Each qubit in turn consists of a niobium crystal, which is placed in an inductor. Electric current, which is fed to the coil, forms a magnetic field. Next, it changes the membership in which the qubit is located. Using such a machine, you can easily find out how synthetic drugs interact with blood proteins.
Or it will be possible to identify a disease such as cancer at an earlier stage.

This video contains discussions on the topic “Why does the world need a quantum computer.” Don't forget to leave your comments, questions and just