China, the United States and Japan are competing in quantum computing. Who will take the lead?

Quantum computers will surpass traditional computers in various areas such as new drug development and code cracking, and will have a huge impact on the industry and national security strategy. It has attracted great attention from governments around the world, and countries such as the United States, China and Japan have begun to make efforts.

Three Kingdoms compete in the field of quantum computer development, who will take the lead?

The market potential is great and the strategic significance is great

Quantum computers can perform certain large-scale calculations much faster than the best conventional computers, and can be used in areas such as code cracking, big data optimization, weather forecasting, and drug analysis.

The Nihon Keizai Shimbun reported on July 6 that if quantum computers are used to develop revolutionary batteries and drugs, it will benefit all of humanity. At a higher level, quantum computers are expected to crack network passwords, thus affecting security, and countries that master quantum technology will take the lead in the high-tech field.

Data from the Boston Consulting Group in the United States shows that quantum computers are expected to generate $850 billion in profits by 2050. Japan's Design News website also pointed out in a report on July 6 that the quantum computer market is expected to be worth $1 trillion in the next 30 years.

United States: Develop commercial quantum computers in 2029

It is the potential and financial power of quantum computers that have attracted governments, businesses and scientists to compete for them.

In May this year, Google announced its ongoing quantum computer development plan, with the goal of developing the first commercial quantum computer by 2029.

In fact, as early as 2019, Google used its 53-qubit quantum computer "Symbol" to solve a problem that the most advanced supercomputer "Summit" would take 10,000 years to solve in just 200 seconds, successfully achieving a breakthrough in "quantum supremacy" - "quantum supremacy" is used to mean "after the storage and communication bandwidth increase exponentially, quantum computers have capabilities that traditional supercomputers do not have."

What Google is thinking about most is "quantum computers as general-purpose products." They hope to use them to solve various difficult problems that existing computers are helpless to solve, such as helping to develop new materials to cope with climate change and drugs to curb global pandemics.

To solve the envisioned problems, the current number of quantum bits is far from enough. Google plans to increase the number of quantum bits to 1 million, and will also solve the biggest problem of errors in calculations. However, increasing the number of quantum bits means that the wiring and control of computers will be more difficult, so large-scale technological innovation is needed. For this purpose, Google has established a new R&D base in California, USA.

According to Science magazine, IBM said in September last year that it would build a quantum computer with 1,000 quantum bits by 2023 while improving its fault tolerance.

From a national perspective, in 2018, the United States finalized its national strategy in the field of quantum information science with quantum computers at its core, and implemented the National Quantum Initiative Act, which will invest up to US$1.3 billion over five years.

China: Overtaking on a curve to achieve "quantum supremacy"

The Design News website reports that there are several different ways to make quantum bits: superconductivity, photons, ion traps, and electron spins in semiconductors (silicon).

Currently, Google and IBM have been working to develop quantum computers using zero-resistance superconducting circuits. Their core research goal is to increase the number of controllable quantum bits and improve the accuracy of manipulation, and ultimately apply them to practical problems.

In this regard, China has already caught up. According to Science magazine, in May this year, the team of Academician Pan Jianwei announced the successful construction of the "Zu Chongzhi", a programmable superconducting quantum computing prototype with the largest number of superconducting quantum bits, containing 62 bits, and realized programmable two-dimensional quantum walks, which has potential applications in quantum search algorithms, general quantum computing and other fields. In June this year, the research team continued its efforts and successfully upgraded the "Zu Chongzhi" from 62 superconducting quantum bits to 66 superconducting quantum bits, thus completing the task that the world's most powerful supercomputer can only complete in 8 years in 1.2 hours.

Schematic diagram of a two-dimensional superconducting quantum bit chip, where each orange cross represents a quantum bit. Image source: University of Science and Technology of China

In addition to the superconducting method, the University of Science and Technology of China used photons as early as 2020 to achieve "quantum supremacy" after Google: it successfully built a quantum computing prototype "Jiuzhang" with 76 quantum bits (photons). It is reported that when solving the Gaussian color sampling of 50 million samples, the world's fastest supercomputer is expected to take 600 million years, while "Jiuzhang" only takes 200 seconds.

The research team said: "We hope that through 15 to 20 years of hard work, we can develop a universal quantum computer to solve some widely used problems, such as cryptanalysis, weather forecasting, drug design, etc., and further explore some complex problems in the fields of physics, chemistry and biology."

In addition, Alibaba Group will also develop quantum computers. In 2015, the company established a quantum computing laboratory with the Chinese Academy of Sciences, and in 2018 launched a service that can be used through a cloud platform.

Japan: Taking a different approach to speed up the pace

Japan is not to be outdone and has accelerated its pace in developing quantum computers. In April this year, Fujitsu announced that it would cooperate with the RIKEN Institute of Physical and Chemical Research to build a quantum computer with 1,000 qubits in the next few years based on the latter's existing research on advanced superconducting quantum computing technology.

According to a report by the Nihon Keizai Shimbun in May, 50 companies represented by Toyota, Toshiba and NEC Corporation plan to establish a quantum technology research agreement to promote the development of quantum technology.

However, Japan's quantum computer development route is not exactly the same as that of China and the United States. Google and other companies use a method called "quantum gate" to develop quantum computers. This type of quantum computer is called "universal" because it can handle any computing task, but the disadvantage is that it is difficult to keep quantum bits stable, and the difficulty increases with the number of quantum bits.

What is highly anticipated in Japan is the method called "quantum annealing". The characteristic of this quantum computer is that it can quickly find the best answer from a large number of options and is more stable than the quantum gate method. However, the quantum computer that uses the quantum annealing algorithm is no longer a general-purpose quantum computer, but a special machine for solving combinatorial optimization problems, also known as a specialized quantum computer. Many Japanese companies, including NEC, are currently exploring this method.

According to Japanese media reports in July 2019, the quantum annealing machine developed by the National Institute of Informatics in Japan has performance that exceeds that of existing quantum computers. NEC announced a quantum annealing machine research and development plan in December 2018, with the ultimate goal of creating a quantum annealing machine that can support 100,000 quantum bits.

Although research and development work is in full swing, it will take some time for quantum computers to be commercially available on a large scale in the strict sense. Scientific progress has always been a long and arduous journey. To develop commercial quantum computers that are easy to create, manage and expand, countries need to increase investment and researchers need to explore.