Humanity, like 60 years ago, is again on the verge of a major breakthrough in the field of computing technology. Very soon to replace today's computers Quantum computers will come.
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 technology development modern processors 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. Theoretical basis Paul Benioff formulated what quantum computers should look like.
How a quantum computer works
To understand how it works new processor, 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 boolean value 0 or 1. Quantum computers operate on qubits, which can have the logical value 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 special program code that can work according to new principles of calculation.
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. For a very long time, technical journals refused to publish articles on quantum computing, considering this area a common fraudulent ploy 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 inherent in quantum computing will certainly transform our planet beyond recognition.
Other 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 conditions are created around the microscopic elements of a logical machine. environment:
- 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 rarefaction is 100 billion times lower than atmospheric pressure.
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 company Together with NASA, it did not purchase last year from the Canadian research corporation the D-Wave quantum computer, 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 version of the fundamental 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 more high level its evolution.
January 29th, 2017
For me, the phrase “quantum computer” is comparable, for example, to “photon engine”, that is, it is something very complex and fantastic. However, I’m reading in the news now: “a quantum computer is being sold to anyone who wants it.” It’s strange, do they now mean something else by this expression, or is it just a fake?
Let's take a closer look...
HOW IT ALL BEGAN?
It was not until the mid-1990s that the theory of quantum computers and quantum computing became established as a new field of science. As is often the case with great ideas, it is difficult to pinpoint the originator. Apparently, the Hungarian mathematician J. von Neumann was the first to draw attention to the possibility of developing quantum logic. However, at that time, not only quantum, but also ordinary, classical computers had not yet been created. And with the advent of the latter, the main efforts of scientists were aimed primarily at searching and developing new elements for them (transistors, and then integrated circuits), and not to create fundamentally different computing devices.
In the 1960s, the American physicist R. Landauer, who worked at IBM, tried to draw the attention of the scientific world to the fact that calculations are always some physical process, which means it is impossible to understand the limits of our computing capabilities without specifying what physical implementation they are. correspond. Unfortunately, at that time, the dominant view among scientists was that calculation was a kind of abstract logical procedure that should be studied by mathematicians, not physicists.
As computers became more widespread, quantum scientists came to the conclusion that it was practically impossible to directly calculate the state of an evolving system consisting of only a few dozen interacting particles, such as a methane molecule (CH4). This is explained by the fact that in order to fully describe a complex system, it is necessary to keep in computer memory an exponentially large (in terms of the number of particles) number of variables, the so-called quantum amplitudes. A paradoxical situation has arisen: knowing the equation of evolution, knowing with sufficient accuracy all the potentials of interaction of particles with each other and the initial state of the system, it is almost impossible to calculate its future, even if the system consists of only 30 electrons in a potential well, and a supercomputer with RAM is available , the number of bits of which is equal to the number of atoms in the visible region of the Universe (!). And at the same time, to study the dynamics of such a system, you can simply conduct an experiment with 30 electrons, placing them in a given potential and initial state. This, in particular, was noted by the Russian mathematician Yu. I. Manin, who in 1980 pointed out the need to develop a theory of quantum computing devices. In the 1980s, the same problem was studied by the American physicist P. Benev, who clearly showed that a quantum system can perform calculations, as well as the English scientist D. Deutsch, who theoretically developed a universal quantum computer that is superior to its classical counterpart.
Nobel Prize winner in physics R. Feynman attracted much attention to the problem of developing quantum computers. Thanks to his authoritative call, the number of specialists who paid attention to quantum computing increased many times over.
The basis of Shor's algorithm: the ability of qubits to store multiple values simultaneously)
But still for a long time It remained unclear whether the hypothetical computing power of a quantum computer could be used to speed up the solution of practical problems. But in 1994, an American mathematician and employee of Lucent Technologies (USA) P. Shor stunned the scientific world by proposing a quantum algorithm that allows for fast factorization of large numbers (the importance of this problem was already discussed in the introduction). Compared to the best classical method known today, Shor’s quantum algorithm provides a multiple acceleration of calculations, and the longer the factored number, the greater the speed gain. The fast factorization algorithm is of great practical interest for various intelligence agencies that have accumulated banks of undecrypted messages.
In 1996, Shor's colleague at Lucent Technologies L. Grover proposed a quantum algorithm quick search in an unordered database. (An example of such a database is phone book, in which the surnames of subscribers are not arranged alphabetically, but in an arbitrary manner.) The task of searching, selecting the optimal element among numerous options is very often encountered in economic, military, engineering problems, V computer games. Grover's algorithm allows not only to speed up the search process, but also to approximately double the number of parameters taken into account when choosing the optimum.
The real creation of quantum computers was hampered by essentially the only serious problem- errors or interference. The fact is that the same level of interference spoils the process of quantum computing much more intensively than classical computing.
If you say in simple words, That: " a quantum system produces a result that is correct only with some probability. In other words, if you count 2+2, then 4 will only come out to some degree of accuracy. You will never get exactly 4. The logic of its processor is not at all similar to the processor we are used to.
There are methods to calculate the result with a predetermined accuracy, naturally with an increase in computer time.
This feature determines the list of tasks. And this feature is not advertised, and the public gets the impression that a quantum computer is the same as a regular PC (the same 0 and 1), only fast and expensive. This is fundamentally not true.
Yes, and one more thing - for a quantum computer and quantum computing in general, especially in order to use the “power and speed” of quantum computing, special algorithms and models developed specifically for the specifics of quantum computing are needed. Therefore, the difficulty of using a quantum computer lies not only in the availability of hardware, but also in the development of new, hitherto unused calculation methods. "
And now let’s move on again to the practical implementation of a quantum computer: a commercial 512-qubit D-Wave processor has already existed for some time and is even sold!!!
Now, it would seem that this is a real breakthrough!!! And a group of reputable scientists in the equally reputable journal Physical Review convincingly testifies that quantum entanglement effects have indeed been discovered in D-Wave.
Respectively, this device has every right to be called a real quantum computer, architecturally it fully allows for a further increase in the number of qubits, and, therefore, has wonderful prospects for the future... (T. Lanting et al. Entanglement in a Quantum Annealing Processor. PHYSICAL REVIEW X 4, 021041 (2014 ) (http://dx.doi.org/10.1103/PhysRevX.4.021041))
True, a little later, another group of reputable scientists in the no less reputable journal Science, who studied the same D-Wave computing system, assessed it purely practically: how well this device performs its computing functions. And this group of scientists, just as thoroughly and convincingly as the first, demonstrates that in real verification tests that are optimally suited for this design, the D-Wave quantum computer does not provide any speed gain compared to conventional, classical computers. (T.F. Ronnow, M. Troyer et al. Defining and detecting quantum speedup. SCIENCE, Jun 2014 Vol. 344 #6190 (http://dx.doi.org/10.1126/science.1252319))
In fact, there were no tasks for the expensive but specialized “machine of the future” where it could demonstrate its quantum superiority. In other words, the very meaning of the very expensive efforts to create such a device is in great doubt...
The results are as follows: now in the scientific community there is no longer any doubt that in the D-Wave computer processor the operation of the elements actually occurs on the basis of real quantum effects between qubits.
But (and this is an extremely serious BUT) key features in the design of the D-Wave processor are such that during real operation, all its quantum physics does not provide any gain in comparison with conventional powerful computer, having special software tailored to solve optimization problems.
Simply put, not only have the scientists testing D-Wave so far been unable to see a single real-world problem where a quantum computer could convincingly demonstrate its computational superiority, but even the manufacturing company itself has no idea what that problem might be...
It's all about the design features of the 512-qubit D-Wave processor, which is assembled from groups of 8 qubits. At the same time, within these groups of 8 qubits, they all communicate directly with each other, but between these groups the connections are very weak (ideally, ALL qubits of the processor should communicate directly with each other). This, of course, VERY significantly reduces the complexity of building a quantum processor... BUT, this gives rise to a lot of other problems that ultimately result in cryogenic equipment, which is very expensive to operate, cooling the circuit to ultra-low temperatures.
So what are they offering us now?
The Canadian company D-Wave announced the start of sales of its quantum computer D-Wave 2000Q, announced in September last year. Adhering to its own version of Moore's Law, according to which the number of transistors on an integrated circuit doubles every two years, D-Wave placed 2,048 qubits on the QPU (quantum processing unit). The dynamics of growth in the number of qubits on a CPU in recent years looks like this:
2007 — 28
…
— 2013 — 512
— 2014 — 1024
— 2016 — 2048.
Moreover, unlike traditional processors, CPUs and GPUs, doubling qubits is accompanied not by a 2-fold, but by a 1000-fold increase in performance. Compared to a computer with a traditional architecture and configuration of a single-core CPU and 2500-core GPU, the difference in performance is from 1,000 to 10,000 times. All these numbers are certainly impressive, but there are a few “buts”.
Firstly, the D-Wave 2000Q is extremely expensive - $15 million. It is a fairly massive and complex device. Its brain is a CPU made of a non-ferrous metal called niobium, whose superconducting properties (necessary for quantum computers) occur in a vacuum at temperatures close to absolute zero below 15 millikelvin (that's 180 times lower than the temperature in outer space).
Maintaining such an extremely low temperature requires a lot of energy, 25 kW. But still, according to the manufacturer, this is 100 times less than equivalent performance traditional supercomputers. So the performance of the D-Wave 2000Q per watt of power consumption is 100 times higher. If the company manages to continue to follow its “Moore's Law”, then in its future computers this difference will grow exponentially, while maintaining power consumption at the current level.
First, quantum computers have a very specific purpose. In the case of D-Wave 2000Q we are talking about the so-called. adiabatic computers and solving quantum normalization problems. They arise in particular in the following areas:
Machine learning:
Detecting Statistical Anomalies
— finding compressed models
— image and pattern recognition
— neural network training
— verification and approval software
— classification of structureless data
— diagnostics of errors in the circuit
Security and planning
Detection of viruses and network hacking
— distribution of resources and finding optimal paths
— determination of membership in a set
— analysis of chart properties
— factorization of integers (used in cryptography)
Financial modeling
Detecting market instability
— development of trading strategies
— optimization of trading trajectories
— optimization of asset pricing and hedging
— portfolio optimization
Healthcare and medicine
Fraud detection (probably related to health insurance)
— generation of targeted (“molecular targeted”) drug therapy
— optimization of [cancer] treatment using radiotherapy
— creation of protein models.
The first buyer of the D-Wave 2000Q was TDS (Temporal Defense Systems), a company engaged in the field of cyber security. In general, D-Wave products are used by such companies and institutions as Lockheed Martin, Google, NASA Ames Research Center, the University of Southern California and the Los Alamos National Laboratory of the US Department of Energy.
Thus, we are talking about a rare (D-Wave is the only company in the world that produces commercial samples of quantum computers) and expensive technology with a rather narrow and specific application. But the growth rate of its productivity is amazing, and if this dynamics continues, then thanks to the adiabatic computers of D-Wave (which other companies may join over time), we can expect real breakthroughs in science and technology in the coming years. Of particular interest is the combination of quantum computers with such a promising and rapidly developing technology as artificial intelligence - especially since such an authoritative specialist as Andy Rubin sees the future in this.
Yes, by the way, did you know that IBM Corporation allowed Internet users to connect for free to the universal quantum computer it built and experiment with quantum algorithms. This device is not powerful enough to break cryptographic systems with public key, but if IBM's plans come to fruition, then the emergence of more complex quantum computers is just around the corner.
The quantum computer that IBM has made available contains five qubits: four are used to work with data, and the fifth is used to correct errors during calculations. Error correction is the main innovation that its developers are proud of. It will make it easier to increase the number of qubits in the future.
IBM emphasizes that its quantum computer is universal and is capable of executing any quantum algorithms. This distinguishes it from the adiabatic quantum computers that D-Wave is developing. Adiabatic quantum computers are designed to search optimal solution functions and are not suitable for other purposes.
It is believed that universal quantum computers will allow solving some problems that conventional computers cannot do. The most famous example of such a problem is factoring numbers into prime factors. To a regular computer Even a very fast one will take hundreds of years to find the prime factors of a large number. A quantum computer will find them using Shor's algorithm almost as quickly as multiplying integers.
The inability to quickly factor numbers into prime factors is the basis of public key cryptographic systems. If they learn to perform this operation at the speed that quantum algorithms promise, then most of modern cryptography will have to be forgotten.
It is possible to run Shor's algorithm on an IBM quantum computer, but until there are more qubits, this will be of little use. Over the next ten years this will change. By 2025, IBM plans to build a quantum computer containing from fifty to one hundred qubits. According to experts, even with fifty qubits, quantum computers will be able to solve some practical problems.
Here's some more interesting stuff about Computer techologies: read how, but it turns out it’s also possible and what it is
How is quantum computing different from traditional computing?
A common metaphor used to compare the two types of calculations is a coin. In a traditional computer processor, the transistor is either heads or tails. But if you ask which side the coin faces when it spins, you will say that the answer can be both. This is how quantum computing works. Instead of regular bits that represent a 0 or a 1, you have a quantum bit that represents both a 0 and a 1 at the same time until the qubit stops spinning and goes into a resting state.
The state space—or the ability to try through a huge number of possible combinations—is exponential in the case of a quantum computer. Imagine that I have two coins in my hand and I throw them into the air at the same time. As they spin, they represent four possible states. If I toss three coins in the air, they will represent eight possible states. If I toss fifty coins into the air and ask you how many states they represent, the answer will be a number that even the most powerful supercomputer in the world cannot calculate. Three hundred coins—still a relatively small number—would represent more states than there are atoms in the universe.
Why are qubits so fragile?
The reality is that coins, or qubits, eventually stop spinning and collapse into a certain state, be it heads or tails. The goal of quantum computing is to keep them spinning in superposition in multiple states for long periods of time. Imagine that I have a coin spinning on my table and someone is pushing the table. The coin may fall faster. Noise, temperature changes, electrical fluctuations or vibration can all interfere with the qubit's operation and cause it to lose its data. One way to stabilize certain types of qubits is to keep them cold. Our qubits operate in a refrigerator the size of a 55-gallon drum and use a special isotope of helium to cool to near absolute zero temperatures.
How do different types of qubits differ from each other?
There are at least six or seven various types qubits, and about three to four of them are actively being considered for use in quantum computers. The difference is how to manipulate the qubits and make them communicate with each other. Two qubits need to communicate with each other to carry out large "entangled" calculations, and different types qubits become entangled in different ways. The type I described that requires extreme cooling is called a superconducting system, which includes our Tangle Lake processor and quantum computers built by Google, IBM and others. Other approaches use oscillating charges on trapped ions—held in place in a vacuum chamber by laser beams—that act as qubits. Intel doesn't develop trapped ion systems because it requires deep knowledge of lasers and optics that we can't do.
However, we are studying a third type, which we call silicon spin qubits. They look exactly like traditional silicon transistors, but operate on a single electron. Spin qubits use microwave pulses to control the spin of an electron and release its quantum power. This technology is less mature today than superconducting qubit technology, but may have a much better chance of scaling up and becoming commercially successful.
How to get to this point from here?
The first step is to make these quantum chips. At the same time, we carried out simulations on a supercomputer. To run Intel's quantum simulator, you need about five trillion transistors to simulate 42 qubits. Reaching commercial reach requires on the order of a million qubits or more, but starting with a simulator like this one can build the underlying architecture, compilers, and algorithms. Until we have physical systems that contain hundreds to thousands of qubits, it is unclear what kind of software we will be able to run on them. There are two ways to increase the size of such a system: one is to add more qubits, which will require more physical space. The problem is that if our goal is to build million-qubit computers, the math won't allow them to scale well. Another way is to compress the internal dimensions of an integrated circuit, but this approach would require a superconducting system, and it would have to be huge. Spin qubits are a million times smaller, so we are looking for other solutions.
In addition, we want to improve the quality of the qubits, which will help us test the algorithms and build our system. Quality refers to the accuracy with which information is conveyed over time. While many parts of such a system would improve in quality, the biggest advances would come from developing new materials and improving the accuracy of microwave pulses and other control electronics.
The US Subcommittee on Digital Commerce and Consumer Protection recently held a hearing on quantum computing. What do lawmakers want to know about this technology?
There are several hearings associated with different committees. If we take quantum computing, we can say that this is the computing technology of the next 100 years. It is natural for the US and other governments to be interested in their possibility. The European Union has a multi-billion dollar plan to fund quantum research across Europe. China last fall announced a $10 billion research facility that will focus on quantum information science. The question is: what can we do as a country at the national level? A national quantum computing strategy should be led by universities, government and industry working together on different aspects of the technology. Standards are definitely needed from a communications or software architecture perspective. Labor is also a problem. Right now, if I have a job opening for a quantum computing expert, two-thirds of the applicants will probably be from outside the US.
What impact could quantum computing have on the development of artificial intelligence?
Typically, the first proposed quantum algorithms will focus on security (e.g., cryptography) or chemistry and materials modeling. These are problems that are fundamentally insoluble for traditional computers. However, there are a lot of startups and groups of scientists working on machine learning and AI with the introduction of quantum computers, even theoretical. Given the time frame required for AI development, I would expect the emergence of traditional chips optimized specifically for AI algorithms, which in turn will influence the development of quantum chips. Either way, AI will definitely get a boost from quantum computing.
When will we see working quantum computers solving real problems?
The first transistor was created in 1947. The first integrated circuit - in 1958. Intel's first microprocessor—which contained about 2,500 transistors—didn't come out until 1971. Each of these milestones was separated by more than a decade. People think quantum computers are just around the corner, but history shows that any advances take time. If in 10 years we have a quantum computer with several thousand qubits, it will definitely change the world in the same way that the first microprocessor changed it.
Candidate of Physical and Mathematical Sciences L. FEDICHKIN (Physical and Technological Institute of the Russian Academy of Sciences.
Using the laws of quantum mechanics, it is possible to create fundamentally new type computers that will allow solving some problems that are inaccessible to even the most powerful modern supercomputers. The speed of many complex calculations will increase sharply; messages sent over quantum communication lines will be impossible to intercept or copy. Today, prototypes of these quantum computers of the future have already been created.
American mathematician and physicist of Hungarian origin Johann von Neumann (1903-1957).
American theoretical physicist Richard Phillips Feynman (1918-1988).
American mathematician Peter Shor, a specialist in the field of quantum computing. He proposed a quantum algorithm for fast factorization of large numbers.
Quantum bit, or qubit. States correspond, for example, to the direction of the spin of the atomic nucleus up or down.
A quantum register is a chain of quantum bits. One- or two-qubit quantum gates perform logical operations on qubits.
INTRODUCTION, OR A LITTLE ABOUT INFORMATION PROTECTION
What program do you think has sold the most licenses in the world? I won’t risk insisting that I know the right answer, but I definitely know one wrong one: this Not any of the versions Microsoft Windows. The most common operating system is ahead of a modest product from RSA Data Security, Inc. - a program that implements the RSA public key encryption algorithm, named after its authors - American mathematicians Rivest, Shamir and Adelman.
The fact is that RSA algorithm built into most commercial operating systems, as well as many other applications used in various devices- from smart cards to cell phones. In particular, it is also available in Microsoft Windows, which means it is obviously more widespread than this popular operating system. To detect traces of RSA, for example, in Internet browser Explorer (a program for viewing www pages on the Internet), just open the “Help” menu, enter the “About” submenu Internet Explorer) and view a list of used products from other companies. Another common browser, Netscape Navigator, also uses the RSA algorithm. In general, it is difficult to find a well-known company working in the field of high technology that would not buy a license for this program. Today, RSA Data Security, Inc. has already sold more than 450 million(!) licenses.
Why was the RSA algorithm so important?
Imagine that you need to quickly exchange a message with a person who is far away. Thanks to the development of the Internet, such exchange has become available to most people today - you just need to have a computer with a modem or network card. Naturally, when exchanging information over the network, you would like to keep your messages secret from strangers. However, it is impossible to completely protect a long communication line from eavesdropping. This means that when messages are sent, they must be encrypted, and when received, they must be decrypted. But how can you and your interlocutor agree on which key you will use? If you send the key to the cipher over the same line, an eavesdropping attacker can easily intercept it. You can, of course, transmit the key via some other communication line, for example, send it by telegram. But this method is usually inconvenient and, moreover, not always reliable: the other line can also be tapped. It’s good if you and your recipient knew in advance that you would exchange encryption, and therefore gave each other the keys in advance. But what if, for example, you want to send a confidential commercial offer to a possible business partner or buy a product you like in a new online store using a credit card?
In the 1970s, to solve this problem, encryption systems were proposed that use two types of keys for the same message: public (not required to be kept secret) and private (strictly secret). The public key is used to encrypt the message, and the private key is used to decrypt it. You send your correspondent a public key, and he uses it to encrypt his message. All an attacker who has intercepted a public key can do is encrypt his email with it and forward it to someone. But he will not be able to decipher the correspondence. You, knowing the private key (it is initially stored with you), can easily read the message addressed to you. To encrypt reply messages, you will use the public key sent by your correspondent (and he will keep the corresponding private key for himself).
This is exactly the cryptographic scheme used in the RSA algorithm, the most common public key encryption method. Moreover, to create a pair of public and private keys, the following important hypothesis is used. If there are two large ones (requiring more than a hundred decimal digits to be written) simple numbers M and K, then finding their product N=MK will not be difficult (you don’t even need to have a computer for this: a fairly careful and patient person will be able to multiply such numbers with a pen and paper). But to solve the inverse problem, that is, knowing a large number N, decompose it into prime factors M and K (the so-called factorization problem) - almost impossible! This is exactly the problem that an attacker will encounter if he decides to “hack” the RSA algorithm and read the information encrypted with it: in order to find out the private key, knowing the public key, he will have to calculate M or K.
To test the validity of the hypothesis about the practical complexity of factoring large numbers, special competitions have been and are still being held. The decomposition of just a 155-digit (512-bit) number is considered a record. The calculations were carried out in parallel on many computers for seven months in 1999. If this task were performed on one modern personal computer, it would take approximately 35 years of computer time! Calculations show that using even a thousand modern workstations and the best computing algorithm known today, one 250-digit number can be factorized in about 800 thousand years, and a 1000-digit number in 10-25 (!) years. (For comparison, the age of the Universe is ~10 10 years.)
Therefore, cryptographic algorithms like RSA, operating on sufficiently long keys, were considered absolutely reliable and were used in many applications. And everything was fine until then ...until quantum computers appeared.
It turns out that using the laws of quantum mechanics, it is possible to build computers for which the problem of factorization (and many others!) will not be difficult. It is estimated that a quantum computer with only about 10 thousand quantum bits of memory can factor a 1000-digit number into prime factors in just a few hours!
HOW IT ALL BEGAN?
It was not until the mid-1990s that the theory of quantum computers and quantum computing became established as a new field of science. As is often the case with great ideas, it is difficult to pinpoint the originator. Apparently, the Hungarian mathematician J. von Neumann was the first to draw attention to the possibility of developing quantum logic. However, at that time, not only quantum, but also ordinary, classical computers had not yet been created. And with the advent of the latter, the main efforts of scientists were aimed primarily at finding and developing new elements for them (transistors, and then integrated circuits), and not at creating fundamentally different computing devices.
In the 1960s, the American physicist R. Landauer, who worked at IBM, tried to draw the attention of the scientific world to the fact that calculations are always some physical process, which means it is impossible to understand the limits of our computing capabilities without specifying what physical implementation they are. correspond. Unfortunately, at that time, the dominant view among scientists was that calculation was a kind of abstract logical procedure that should be studied by mathematicians, not physicists.
As computers became more widespread, quantum scientists came to the conclusion that it was practically impossible to directly calculate the state of an evolving system consisting of only a few dozen interacting particles, such as a methane molecule (CH 4). This is explained by the fact that in order to fully describe a complex system, it is necessary to keep in computer memory an exponentially large (in terms of the number of particles) number of variables, the so-called quantum amplitudes. A paradoxical situation has arisen: knowing the equation of evolution, knowing with sufficient accuracy all the potentials of interaction of particles with each other and the initial state of the system, it is almost impossible to calculate its future, even if the system consists of only 30 electrons in a potential well, and a supercomputer with RAM is available , the number of bits of which is equal to the number of atoms in the visible region of the Universe (!). And at the same time, to study the dynamics of such a system, you can simply conduct an experiment with 30 electrons, placing them in a given potential and initial state. This, in particular, was noted by the Russian mathematician Yu. I. Manin, who in 1980 pointed out the need to develop a theory of quantum computing devices. In the 1980s, the same problem was studied by the American physicist P. Benev, who clearly showed that a quantum system can perform calculations, as well as the English scientist D. Deutsch, who theoretically developed a universal quantum computer that is superior to its classical counterpart.
Nobel Prize winner in physics R. Feynman, well known to regular readers of Science and Life, attracted much attention to the problem of developing quantum computers. Thanks to his authoritative call, the number of specialists who paid attention to quantum computing increased many times over.
Yet for a long time it remained unclear whether the hypothetical computing power of a quantum computer could be used to speed up the solution of practical problems. But in 1994, an American mathematician and employee of Lucent Technologies (USA) P. Shor stunned the scientific world by proposing a quantum algorithm that allows for fast factorization of large numbers (the importance of this problem was already discussed in the introduction). Compared to the best classical method known today, Shor’s quantum algorithm provides a multiple acceleration of calculations, and the longer the factored number, the greater the speed gain. The fast factorization algorithm is of great practical interest for various intelligence agencies that have accumulated banks of undecrypted messages.
In 1996, Shore's colleague at Lucent Technologies L. Grover proposed a quantum algorithm for fast search in an unordered database. (An example of such a database is a telephone book in which the names of subscribers are not arranged alphabetically, but in an arbitrary manner.) The task of searching, selecting the optimal element among numerous options is very often encountered in economic, military, engineering problems, and in computer games. Grover's algorithm allows not only to speed up the search process, but also to approximately double the number of parameters taken into account when choosing the optimum.
The real creation of quantum computers was hampered by essentially the only serious problem - errors, or interference. The fact is that the same level of interference spoils the process of quantum computing much more intensively than classical computing. P. Shor outlined ways to solve this problem in 1995, developing a scheme for encoding quantum states and correcting errors in them. Unfortunately, the topic of error correction in quantum computers is as important as it is complex to cover in this article.
DEVICE OF A QUANTUM COMPUTER
Before we tell you how a quantum computer works, let us recall the main features of quantum systems (see also “Science and Life” No. 8, 1998; No. 12, 2000).
To understand the laws of the quantum world, one should not rely directly on everyday experience. In the usual way (in the everyday understanding), quantum particles behave only if we constantly “peep” at them, or, more strictly speaking, constantly measure the state in which they are. But as soon as we “turn away” (stop observing), quantum particles immediately move from a very specific state into several different forms at once. That is, an electron (or any other quantum object) will be partially located at one point, partially at another, partially at a third, etc. This does not mean that it is divided into slices, like an orange. Then it would be possible to reliably isolate some part of the electron and measure its charge or mass. But experience shows that after measurement, the electron always turns out to be “safe and sound” at one single point, despite the fact that before that it managed to be almost everywhere at the same time. This state of an electron, when it is located at several points in space at once, is called superposition of quantum states and are usually described by the wave function, introduced in 1926 by the German physicist E. Schrödinger. The modulus of the value of the wave function at any point, squared, determines the probability of finding a particle at that point in this moment. After measuring the position of a particle, its wave function seems to shrink (collapse) to the point where the particle was detected, and then begins to spread out again. The property of quantum particles to be in many states simultaneously, called quantum parallelism, has been successfully used in quantum computing.
Quantum bit
The basic cell of a quantum computer is a quantum bit, or, for short, qubit(q-bit). This is a quantum particle that has two basic states, which are designated 0 and 1 or, as is customary in quantum mechanics, and. Two values of the qubit can correspond, for example, to the ground and excited states of the atom, the up and down directions of the spin of the atomic nucleus, the direction of the current in the superconducting ring, two possible positions of the electron in the semiconductor, etc.
Quantum register
The quantum register is structured almost the same as the classical one. This is a chain of quantum bits on which one- and two-bit logical operations can be performed (similar to the use of NOT, 2I-NOT, etc. operations in a classical register).
The basic states of a quantum register formed by L qubits include, as in the classical one, all possible sequences of zeros and ones of length L. There can be 2 L different combinations in total. They can be considered a record of numbers in binary form from 0 to 2 L -1 and denoted. However, these basic states do not exhaust all possible values of the quantum register (unlike the classical one), since there are also superposition states defined by complex amplitudes related by the normalization condition. A classical analogue for most possible values of a quantum register (except for the basic ones) simply does not exist. The states of a classical register are just a pitiful shadow of the entire wealth of states of a quantum computer.
Imagine that the register is carried out external influence, for example, electrical impulses are applied to a part of the space or laser beams are directed. If it is a classical register, an impulse, which can be considered as a computational operation, will change L variables. If this is a quantum register, then the same pulse can simultaneously convert to variables. Thus, a quantum register is, in principle, capable of processing information several times faster than its classical counterpart. From here it is immediately clear that small quantum registers (L<20) могут служить лишь для демонстрации отдельных узлов и принципов работы квантового компьютера, но не принесут большой практической пользы, так как не сумеют обогнать современные ЭВМ, а стоить будут заведомо дороже. В действительности квантовое ускорение обычно значительно меньше, чем приведенная грубая оценка сверху (это связано со сложностью получения большого количества амплитуд и считывания результата), поэтому практически полезный квантовый компьютер должен содержать тысячи кубитов. Но, с другой стороны, понятно, что для достижения действительного ускорения вычислений нет необходимости собирать миллионы квантовых битов. Компьютер с памятью, измеряемой всего лишь в килокубитах, будет в некоторых задачах несоизмеримо быстрее, чем классический суперкомпьютер с терабайтами памяти.
It is worth noting, however, that there is a class of problems for which quantum algorithms do not provide significant acceleration compared to classical ones. One of the first to show this was the Russian mathematician Yu. Ozhigov, who constructed a number of examples of algorithms that, in principle, cannot be accelerated by a single clock cycle on a quantum computer.
Nevertheless, there is no doubt that computers operating according to the laws of quantum mechanics are a new and decisive stage in the evolution of computing systems. All that remains is to build them.
QUANTUM COMPUTERS TODAY
Prototypes of quantum computers already exist today. True, so far it has been experimentally possible to assemble only small registers consisting of only a few quantum bits. Thus, recently a group led by American physicist I. Chang (IBM) announced the assembly of a 5-bit quantum computer. Undoubtedly, this is a great success. Unfortunately, existing quantum systems are not yet capable of providing reliable calculations, as they are either poorly controlled or very susceptible to noise. However, there are no physical restrictions on building an effective quantum computer; it is only necessary to overcome technological difficulties.
There are several ideas and proposals on how to make reliable and easily controllable quantum bits.
I. Chang develops the idea of using the spins of the nuclei of some organic molecules as qubits.
Russian researcher M.V. Feigelman, working at the Institute of Theoretical Physics named after. L.D. Landau RAS, proposes to assemble quantum registers from miniature superconducting rings. Each ring plays the role of a qubit, and states 0 and 1 correspond to the direction of the electric current in the ring - clockwise and counterclockwise. Such qubits can be switched using a magnetic field.
At the Institute of Physics and Technology of the Russian Academy of Sciences, a group led by Academician K. A. Valiev proposed two options for placing qubits in semiconductor structures. In the first case, the role of a qubit is played by an electron in a system of two potential wells created by a voltage applied to mini-electrodes on the surface of the semiconductor. States 0 and 1 are the positions of the electron in one of these wells. The qubit is switched by changing the voltage on one of the electrodes. In another version, the qubit is the nucleus of a phosphorus atom embedded at a certain point of the semiconductor. States 0 and 1 - directions of nuclear spin along or against the external magnetic field. Control is carried out using the combined action of magnetic pulses of resonant frequency and voltage pulses.
Thus, research is actively underway and it can be assumed that in the very near future - in about ten years - an effective quantum computer will be created.
A LOOK INTO THE FUTURE
Thus, it is quite possible that in the future, quantum computers will be manufactured using traditional methods of microelectronic technology and contain many control electrodes, reminiscent of a modern microprocessor. In order to reduce the noise level, which is critical for the normal operation of a quantum computer, the first models will apparently have to be cooled with liquid helium. It is likely that the first quantum computers will be bulky and expensive devices that will not fit on a desk and are maintained by a large staff of systems programmers and hardware adjusters in white coats. First, only government agencies will have access to them, then wealthy commercial organizations. But the era of conventional computers began in much the same way.
What will happen to classic computers? Will they die off? Hardly. Both classical and quantum computers have their own areas of application. Although, most likely, the market ratio will gradually shift towards the latter.
The introduction of quantum computers will not lead to the solution of fundamentally unsolvable classical problems, but will only speed up some calculations. In addition, quantum communication will become possible - the transfer of qubits over a distance, which will lead to the emergence of a kind of quantum Internet. Quantum communication will make it possible to provide a secure (by the laws of quantum mechanics) connection of everyone with each other from eavesdropping. Your information stored in quantum databases will be more reliably protected from copying than it is now. Firms producing programs for quantum computers will be able to protect them from any, including illegal, copying.
For a deeper understanding of this topic, you can read the review article by E. Riffel and V. Polak, “Fundamentals of Quantum Computing,” published in the Russian journal “Quantum Computers and Quantum Computing” (No. 1, 2000). (By the way, this is the first and so far the only journal in the world dedicated to quantum computing. Additional information about it can be found on the Internet at http://rcd.ru/qc.). Once you have mastered this work, you will be able to read scientific articles on quantum computing.
Somewhat more preliminary mathematical preparation will be required when reading the book by A. Kitaev, A. Shen, M. Vyaly “Classical and Quantum Computations” (Moscow: MTsNMO-CheRo, 1999).
A number of fundamental aspects of quantum mechanics, essential for carrying out quantum calculations, are discussed in the book by V. V. Belokurov, O. D. Timofeevskaya, O. A. Khrustalev “Quantum teleportation - an ordinary miracle” (Izhevsk: RHD, 2000).
The RCD publishing house is preparing to publish a translation of A. Steen's review on quantum computers as a separate book.
The following literature will be useful not only educationally, but also historically:
1) Yu. I. Manin. Computable and incomputable.
M.: Sov. radio, 1980.
2) J. von Neumann. Mathematical foundations of quantum mechanics.
M.: Nauka, 1964.
3) R. Feynman. Simulation of physics on computers // Quantum computer and quantum computing:
Sat. in 2 volumes - Izhevsk: RHD, 1999. T. 2, p. 96-123.
4) R. Feynman. Quantum mechanical computers
// Ibid., p. 123.-156.
See the issue on the same topic
Hello again to all readers of my blog! Yesterday, a couple of stories about a “quantum” computer once again appeared in the news. We know from the school physics course that a quantum is a certain equal portion of energy, there is also the phrase “quantum leap”, that is, an instant transition from a certain energy level to an even higher level.. Let's figure out together what a quantum computer is and what We are all waiting for this miracle machine to appear
I first became interested in this topic while watching films about Edward Snowden. As you know, this American citizen collected several terabytes of confidential information (compromising evidence) about the activities of the US intelligence services, thoroughly encrypted it and posted it on the Internet. “If, he said, anything happens to me, the information will be deciphered and thus become available to everyone.”
The calculation was that this information was “hot” and would be relevant for another ten years. And it can be decrypted with modern computing power in no less than ten or more years. The quantum computer, according to the developers' expectations, will cope with this task in about twenty-five minutes. Cryptographers are in a panic. This is the kind of “quantum” leap that awaits us soon, friends.
Principles of operation of a quantum computer for dummies
Since we're talking about quantum physics, let's talk a little about it. I won't go into the weeds, friends. I’m a “teapot”, not a quantum physicist. About a hundred years ago, Einstein published his theory of relativity. All the smart people of that time were surprised at how many paradoxes and incredible things there were in it. So, all of Einstein’s paradoxes that describe the laws of our world are just the innocent babble of a five-year-old child compared to what is happening at the level of atoms and molecules.
The “quantum physicists” themselves, who describe the phenomena occurring at the levels of electrons and molecules, say something like this: “This is incredible. This can't be true. But it is so. Don't ask us how it all works. We don't know how or why. We're just watching. But it works. This has been proven experimentally. Here are the formulas, dependencies and records of experiments.”
So what is the difference between a conventional and a quantum computer? After all, an ordinary computer also runs on electricity, and electricity is a bunch of very small particles - electrons?
Our computers work on the principle of either “Yes” or “No”. If there is current in the wire, it is “Yes” or “One”. If there is “No” current in the wire, then it is “Zero”. The value option "1" and "0" is a unit of information storage called "Bit".. One byte is 8 bits and so on and so on...
Now imagine your processor, on which there are 800 million such “wires”, on each of which such a “zero” or “one” appears and disappears in a second. And you can mentally imagine how he processes information. You are reading the text now, but in fact it is a collection of zeros and ones.
By brute force and calculations, your computer processes your requests in Yandex, searches for the ones you need until it solves the problem and, through elimination, gets to the bottom of the one you need. Displays fonts and pictures on the monitor in a form we can read... So far, I hope nothing complicated? And the picture is also zeros and ones.
Now, friends, imagine for a second a model of our solar system. The Sun is in the center and the Earth flies around it. We know that at a certain moment it is always at a certain point in space, and in a second it will fly thirty kilometers further.
So, the model of the atom is also planetary, where the atom also rotates around the nucleus. But it has been PROVEN, friends, by smart guys in glasses, that the atom, unlike the Earth, is simultaneously and always in all places... Everywhere and nowhere at the same time. And they called this wonderful phenomenon “superposition”. In order to get to know other phenomena of quantum physics better, I suggest watching a popular science film that talks about complex things in simple language and in a rather original form.
Let's continue. And now “our” bit is replaced by a quantum bit. It is also called “Qubit”. It also has only two initial states “zero” and “one”. But, since its nature is “quantum”, it can SIMULTANEOUSLY take on all possible intermediate values. And at the same time be in them. Now you don’t have to sequentially calculate the values, sort through them... or search for a long time in the database. They are already known in advance, right away. Calculations are carried out in parallel.
The first “quantum” algorithms for mathematical calculations were invented by English mathematician Peter Shore in 1997. When he showed them to the world, all the cryptographers became very tense, since existing ciphers are “cracked” by this algorithm in a few minutes. But there were no computers working using the quantum algorithm at that time.
Since then, on the one hand, work has been going on to create a physical system in which a quantum bit would work. That is, “hardware”. On the other hand, they are already coming up with protection against quantum hacking and data decryption.
What now? And this is what a quantum processor looks like under a 9-qubit microscope from Google.
Have they really overtaken us? 9 qubits or according to the “old” 15 bits, this is not so much yet. Plus the high cost, a lot of technical problems and the short “lifetime” of quanta. But remember that first there were 8-bit processors, then 16-bit processors appeared... The same will happen with these...
Quantum computer in Russia - myth or reality?
What about us? But we weren’t born behind the stove. Here I dug up a photo of the first Russian Cubit under a microscope. He's really the only one here. 
It also looks like a kind of “loop” in which something is happening that is not yet known to us. It’s gratifying to think that ours, with the support of the state, are developing their own. So domestic developments are no longer a myth. This is our future. We'll see what it will be like.
Latest news about Russia's 51-qubit quantum computer
Here's the news for this summer. Our guys (honor and praise to them!) have developed the most powerful in the world (!) quantum (!) computer 51 qubits (!) i.e. The most interesting thing is that before this Google announced its 49 qubit computer. And they estimated they would have it finished in a month or so. And ours decided to show a ready-made, 51-qubit quantum processor... Bravo! That's the race going on. At least we can keep up. Because a big breakthrough in science is expected when these systems work. Here is a photo of the person who presented our development at the “quantum” international forum.
The name of this scientist is Mikhail Lukin. Today his name is in the spotlight. It is impossible to create such a project alone, we understand this. He and his team created the most powerful quantum computer or processor in the world today (!). Here's what competent people have to say about this:
« A functioning quantum computer is much more terrible than an atomic bomb,” notes Sergei Belousov, co-founder of the Russian Quantum Center. - He (Mikhail Lukin) made a system that has the most qubits. Just in case. At this point, I think that's more than twice as many qubits as anyone else. And he specifically made 51 qubits, not 49. Because Google kept saying that they would make 49.”
However, Lukin himself and the head of the Google quantum laboratory, John Martinez, do not consider themselves competitors or rivals. Scientists are convinced that their main rival is nature, and their main goal is the development of technology and its implementation to advance humanity to a new stage of development.
“It's wrong to think of this as a race,” John Martinez rightly says. - We have a real race with nature. Because it's really difficult to create a quantum computer. And it's just exciting that someone managed to create a system with so many qubits. So far, 22 qubits is the maximum we could do. Even though we used all our magic and professionalism.”
Yes, this is all very interesting. If we recall analogies, when the transistor was invented, no one could have known that computers would work on this technology 70 years later. In a modern processor alone, their number reaches 700 million. The first computer weighed many tons and occupied large areas. But personal computers still appeared - much later...
I think that for now we should not expect devices of this class to appear in our stores in the near future. Many are waiting for them. Especially cryptocurrency miners argue a lot about this. Scientists look at him with hope, and military men look at him with close attention. The potential of this development, as we understand it, is not completely clear.
It is only clear that when it all starts working, it will drag the entire knowledge-intensive industry forward with it. New technologies, new industries, new software will gradually appear.. Time will tell. If only our own quantum computer, given to us at birth, does not let people down - this is our head. So, don’t rush to throw your gadgets into the trash just yet. They will serve you for a long time. Write if the article was interesting. Come back often. Goodbye!
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