Quantum technology, such as quantum computers, is often talked about as the latest technology that will change the future. But what exactly is a quantum computer? How will it change society?
We asked some of the mysteries surrounding quantum technology, from the misconception that they have more amazing processing performance than today's computers, to whether or not Japan has the potential to lead the world.
--Quantum computers are often mentioned in the news. Why is quantum computing attracting so much attention?
Mr A: The theory and technology involved in quantum computers is very difficult, so I will try to simplify it as much as possible. The word quantum comes from ‘quantum mechanics’, a branch of physics. This is the study that describes and elucidates the molecules and atoms, which are the units that make up matter, and the electrons that make them up.
Quantum technology is the application of the theories and phenomena of quantum mechanics to create unconventional science and technology. And among quantum technology, quantum is particularly applied to the development of computers, which are called quantum computers.
Mr B: The reason why the term quantum computer has recently started to appear in the news is that quantum computers, which had been talked about in theory, have actually been developed and put into operation over the past few years. However, we are still at the stage where some large companies and specialised institutions have finally started to operate a kind of trial machine.
A: The computer technology that formed the basis of the personal computers and smartphones we use today was initially used only by a very limited number of people in the fields of science and technology. This was followed by home computers, which became available to the general public, and then by the explosion of smartphones.
If we compare the history of computers to this, the quantum computer is still in its early stages and is only used by a few researchers.
-The general feeling is that ‘quantum computers? It looks like something great, but I don't really understand it’. For example, the terms NFT and metaverse, which became a hot topic last year, were temporarily covered widely in the media, but so far they do not seem to be of any use to society, and news that related companies are downsizing their operations is increasing.
There are also questions as to whether quantum computers are also a kind of hype. There is a question as to whether quantum computers are also like hype.
A: Quantum computers are being developed in reality, are actually in operation and have achieved a certain level of success. However, some of the news about quantum computers could be said to be hype or lies.
Mr B: Stories such as ‘quantum computers are hundreds of millions of times faster than current computers and supercomputers’ are common ‘misconceptions’ about quantum computers.
In 2019, Google announced in a scientific journal that its proprietary quantum computer performed a process in 200 seconds that would take even the world's fastest supercomputer 10,000 years. Since then, the misconception has spread that quantum computers have better processing performance than supercomputers.
But in reality, the paper was actually saying, ‘We set a problem that quantum computers are good at and let the quantum computer solve it, and it was indeed fast’. In other words, it would be like saying, ‘If you ask a child who is good at maths and a child who is good at Japanese to solve a maths problem, the child who is good at maths got the better grade’. But that doesn't mean that children who are good at Japanese are inferior in all areas.
A: Of course, what Google has published is a very important research result, as it shows that quantum computers have an advantage over existing supercomputers ‘in certain fields’. Nevertheless, such misconceptions may arise because a correct understanding of quantum computers is not widespread.
Also, as with the metaverse and NFTs, there is an aspect of the technology that seems to have been over-hyped before it has matured as a technology. Quantum computers are not an update of existing computers, but rather a high performer in a different field to existing computers. It is not as if the progress of quantum computer research will make the computers we use in our daily lives more powerful.
▶︎ supercomputer (supercomputer)
Computers that are much larger and faster than ordinary computers, used for scientific and technological research.
K computer’ and “Fugaku” are known as Japanese supercomputers.
--What kind of processing are quantum computers good at?
A: To understand this, it is necessary to understand the difference between the processing carried out by conventional computers and that carried out by quantum computers. The computers we use in our everyday lives perform computational processing in binary units called ‘bits’.
Bits have the states ‘0’ and ‘1’, and it is the combination of these two that performs the calculation process. The more combinations of 0s and 1s there are, the more processing is possible.
On the other hand, in the quantum world, there is the phenomenon of having both ‘0’ and ‘1’ states at the same time, and this unit is called a quantum bit. The quantum computer uses this quantum property.
Mr B: This is a very difficult subject, so I'll give you an example that is easy to visualise. The world of bits is something that can be described as ‘whether a coin is two sides of the same coin’ or ‘whether a coin is a front’. This is understandable because it is still a phenomenon that we normally experience.
But in the quantum world, there is the phenomenon that ‘a coin may be two sides or one side’. Of course, when we witness a coin in the real world, such a situation is not possible. This is the difficult part, but you have to understand that this is possible in the quantum world.
Thus, in the first place, there is a fundamental difference between bit and quantum in the way computations are processed. And it is known that quantum computers excel at processing such as ‘finding the best combination for a problem where there are multiple combinations’ by using these quantum properties.
A: A relatively familiar example is prime factorisation. Prime factorisation is a calculation in which a specific large number (21) is expressed as a multiplication of prime numbers, such as ‘21 = 3 x 7’. 21 or so can be solved quickly by today's computers, but the larger this number is, the more complex the calculation process becomes. Even supercomputers, which have the highest performance of all computers, are said to take tens of thousands of years to produce an answer with more than 600 digits.
However, in 1994, an American mathematician called Peter Shore discovered that if a quantum computer is used to perform calculations according to a specific algorithm, it can do prime factorisation much faster than a normal computer.
Mr B: Thus, certain computational processes that would take too long on a conventional computer can be processed in a very short time on a quantum computer. In particular, it is thought that quantum computers are particularly good at problems where the optimum answer can be found from a large number of conditions and variables.
A: Incidentally, there are two types of quantum computer, gated and annealing, and the gated type can be used for general purposes such as combinatorial optimisation calculations, prime factorisation and machine learning.
On the other hand, the annealing type is a quantum computer specialising in combinatorial optimisation calculations, and at the present time, actual development is progressing on the annealing type. Research is currently underway into the fields in which the characteristics of these quantum computers can be used.
--One example is the use of quantum computers in traffic jams.
A: One example is the problem of traffic congestion. For example, if a large number of cars try to use a car navigation system to reach a single destination in the shortest possible distance, there will be a traffic jam. If, then, many cars take side roads to get to their destinations, then traffic jams will occur there as well.
In this way, even if individual cars think they have chosen the best route for themselves, the overall result is that everyone loses out.
The question then arises as to which combination of routes each car chooses that will result in the least amount of traffic congestion. This kind of problem is also called a ‘combinatorial optimisation problem’, and is a computational process in which quantum computers excel.
Conventional computers perform calculations one at a time, such as ‘if car A chooses route A, car A chooses route B...’ But if the number of cars and routes increases, the number of calculation processes increases exponentially, and in reality it becomes impossible to perform calculations.
Mr B: Currently, there are four areas where the application of quantum computers is said to have particular benefits, such as increased efficiency: optimisation calculations, machine learning (AI), simulation and cryptography. Optimisation computation’ refers to computational processes for selecting the optimum one among multiple combinations, as in the example of traffic congestion mentioned earlier.
Specifically, it is expected to be used in the supply chain and logistics industry to instantly identify the optimum method from multiple factors, such as delivery routes, cargo distribution and procurement method selection. In the financial sector, the system is also being considered for use in investment risk diversification and portfolio optimisation.
In the investment field, there are many investment candidates, and many factors are involved, such as changes in social conditions, the performance of individual companies and technological developments, so the quantum computer is used to calculate the most suitable one among them.
A: Quantum computers are also good at processing huge amounts of data, so they are expected to be used for machine learning, which is a hot topic in AI technology these days. In addition, quantum mechanics is a physics science about molecules and electrons, so it is said to be compatible with the field of chemistry, which uses them.
For example, quantum computers can be used to investigate the structure of substances and simulate how molecules interact with each other, which is expected to be useful in the development of pharmaceuticals. Quantum technology is also expected to develop the deciphering of codes and the secrecy of communications.
--I have heard people say that blockchain technology will collapse if quantum computers are used to decode encryption.
Mr B: That is another common ‘misconception’ about quantum computers. Blockchain technology uses a number of cryptographic techniques, which keep, for example, the assets in a wallet secure. However, with a quantum computer and the right algorithms, it is theoretically possible to decrypt the secret password, called the private key, from the wallet address, which is publicly available to the world.
Current encryption technology is such that even with classical computers such as supercomputers (*Computers currently used in contrast to quantum computers are called ‘classical computers’), it would take tens of thousands of years or more to decrypt them, whereas quantum computers have the potential to do so in a shorter time. Quantum computers have the potential to do so in a shorter time.
However, not only cryptographic assets and blockchains, but also many online banks and online services use cryptographic techniques that are ‘difficult to analyse with classical computers, but can be analysed in a short time with quantum computers’. So if cryptanalysis can be done by quantum computers, the current internet will collapse before the blockchain collapses.
In fact, however, with the development of quantum computers, research is also progressing into a cryptographic technique called ‘quantum resistant cryptography’, which cannot be analysed even by a quantum computer.
It is true that if current cryptography is used as it is, not only blockchains but also various other cryptographies will one day be analysed, but before that happens, cryptography that is compatible with quantum computers should spread.
A: Many of the cryptographic techniques currently used on the internet ensure security through the difficulty of prime factorisation introduced earlier. And since prime factorisation is exactly what quantum computers are good at, they can analyse cryptography in a very short time. However, if quantum computers are going to spread, there is no need to worry too much, as ‘quantum resistant cryptography’ should spread before that.
--I understand that quantum computers are still in their infancy, but what is Japan's position in this field?
A: Currently, the US and China are making great progress in quantum computer research, while Japan is many laps behind. Compared to quantum computer research in the US and China, it is estimated that only about one-fifth of the budget is invested in Japan.
However, it is expected to take five to ten years or more for quantum computers to be put into practical use, so the delay at the moment is not fatal.
Mr B: In April 2022, Japan formulated a national strategy called the ‘Quantum Future Society Vision’, which positioned ‘quantum computers and other quantum technologies as extremely important in terms of solving social issues and economic security’.
It also presents an image of how this technology will be utilised in various industrial fields in the future, and is strengthening its efforts to develop research and development centres, create start-ups and foster human resources.
Furthermore, the goals set for 2030 include ‘increasing the number of domestic users of quantum technology to 10 million’, ‘increasing the production value of quantum technology to 50 trillion yen’ and ‘creating quantum unicorn venture companies that will pioneer the future market’. We have stated that we will focus on this field as a national strategy.
A: In March 2023, a group led by RIKEN began operating the first domestically produced quantum computer.
This domestically produced quantum computer has 64 qubits. Think of a qubit as a number, where the larger the number, the more complex the computational process: 64 qubits means that it can simultaneously compute approximately 1,845 kyoku of information, or 64 to the power of 2.
Incidentally, IBM has announced that it plans to develop a 4,000-qubit quantum computer by 2025, and Google plans to develop a one million-qubit quantum computer by 2029, so Japan will also be aiming for these figures.
Mr B: Of course, it would be wonderful if we could develop the world's best quantum computer, but this field is a combination of many technologies and components. It would be a great achievement if we could create something that the world depends on Japan for at least one of these, such as technology for utilising quantum computers or manufacturing the components used in the hardware.
The development of algorithms that allow quantum computers to perform appropriate computational processes and software development is still in its early stages, so it is also essential to invest as much money as possible to foster excellent human resources.
A: There are still many breakthroughs to be made before quantum computers can be used in earnest. In other words, there is plenty of room for Japan to occupy an important position.
Mr B: If quantum computers are put to practical use, it is expected that, for example, only companies in certain industries that use quantum computers will be able to win alone. Of course, the countries that are the first to put the technology to practical use will be the ones that lead the way.
As explained earlier, there are many areas where quantum computers will be used, and new applications will be discovered in the future. Even companies in fields that may feel that quantum computers are not relevant at the moment should be aware of the extent to which this technology is being put to practical use.
The applications currently envisaged are only those that can be envisaged when quantum computers are not yet perfected. For example, when smartphones did not exist, no one could have imagined that they would become indispensable in our daily lives.
The next five years or so will determine whether we can ride the wave of the quantum computer era, which will undoubtedly arrive in more than a decade.
As many people know, Japan is no longer the world leader in the field of computing. Even if you are not directly involved in quantum computing, I would be happy if you could support Japan to make its presence felt on this stage.
◉Mr A.
Married man in his 40s. After working as a hardware developer, he joined the research department of a major Japanese IT company. He is engaged in research and development of quantum computers and quantum technology. A recent good thing he bought was a pair of VR goggles, the Meta Quest 2. On his days off, he plays VR golf exclusively at home, to the dismay of his family.
◉Mr B.
Male in his 20s. He studied quantum mechanics at university and currently works as an IT journalist, mainly for computer magazines. His hobby is building his own PCs, and he runs a home-built PC website in addition to his day job. A recent good purchase was the Google Pixel 7a. He was a long-time Apple devotee, but finally converted after considering cost-effectiveness.
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