Pan Jianwei: 255 photon computing prototypes have been implemented and the first mid to high orbit quantum satellite is being developed

In 2020, the quantum computing prototype "Nine Chapters" with 76 photons solved a specific problem of Gaussian Persian sampling at a speed of 100000 times that of the fastest classical supercomputer at the time. Recently, Pan Jianwei's team has implemented a prototype machine for calculating the amount of 933 photons with 255 photons, which has a problem-solving ability that is 1000 trillion times faster than classic supercomputers.

We are currently developing the first mid to high orbit quantum satellite, with plans to launch around 2026. At the same time, Pan Jianwei stated that he plans to carry an ultra high precision optical clock on a medium to high orbit satellite, which will have a stability of 10-19 power, meaning an error of no more than one second per year.

Pan Jianwei, academician of the CAS Member, president of the quantum information and Quantum Technology Innovation Institute of the Chinese Academy of Sciences, and executive vice president of the University of Science and Technology of China, made a video speech.

In 2020, we implemented a 76 photon quantum computing prototype called 'Chapter 9', which was 100000 times faster than the fastest classical supercomputer at the time in solving specific problems with Gaussian Persian sampling. Our system has been continuously upgraded, and recently we have implemented a 255 photon quantum computing prototype called '933', which has a problem-solving ability that is 10 million times faster than classical supercomputers One billion times On May 10, at the third BEYOND International Science and Technology Innovation Expo (BEYONDExpo2023) held in Macao, Pan Jianwei, an academician of the CAS Member, president of the quantum information and Quantum Technology Innovation of the Chinese Academy of Sciences, and executive vice president of the University of Science and Technology of China, introduced the current work in quantum science and technology and future prospects in this field.

Pan Jianwei led the development of the world's first quantum science experiment satellite "Mozi", built the world's first quantum secure communication backbone network "Beijing Shanghai trunk line", and built the first space ground integrated wide area quantum secure communication network prototype.

At the meeting, Pan Jianwei revealed that "we are currently developing the first mid to high orbit quantum satellite and plan to launch it around 2026. In addition to achieving quantum key distribution, this also provides a new platform for quantum precision measurement of mid to high orbit satellites." At the same time, Pan Jianwei stated that he plans to install an ultra high precision optical clock on the mid to high orbit satellite, which will have a stability of 10-19 power, which means that the error in one year will not exceed one second.

The following is a transcript of Pan Jianwei's speech on BEYONDExpo2023 organized by Pengpai Technology (www.thetaper. cn):

The Nobel Prize in Physics in 2022 was awarded to three pioneers in the field of quantum science and technology, in recognition of their use of entangled photons to achieve the violation of Bell's inequality (meaning that the entangled particle pair is indeed an inseparable whole, and it is impossible to endow each particle with a separate local property), and thus to create quantum information science. I am very pleased that in the press conference and scientific background introduction of the 2022 Nobel Prize in Physics, the relevant work of Chinese scientists was highlighted, including the key distribution of the Mozi quantum satellite for satellite to earth, the quantum teleportation of the Earth star, and the work of our latest device, the lightless quantum key distribution.

To facilitate your understanding, please allow me to briefly introduce the quantum superposition principle. Everyone knows that in our daily lives, a cat can only be in one of the living or dead states at a certain moment. However, according to the quantum superposition principle, a cat can be in two states at the same time in quantum events. When the quantum superposition principle is extended to the multi particle system, we can get the concept of quantum entanglement. For example, in the quantum world, two cats can be in a correlated superposition of live and dead states simultaneously. This state is like two dice, no matter how far apart they are, one must roll the same number of points as the other. Einstein called this phenomenon of quantum entanglement the weird interaction between distant places.

In physics, any two-level system (including a quantum system with two energy levels) can be used to construct a quantum bit. For example, we can encode the information of a quantum bit using two polarization states: a photon level and a mass. For a two-photon quantum system, it can be in the four largest polarization entanglements. Then, Bell inequality is used to test the process of the definition of quantum mechanics, from which physicists have developed a quantum technology that can control the quantum system with high precision, leading to the birth of quantum information science.

Quantum information science mainly includes two applications: first, we can provide a unconditionally secure communication method by using quantum communication. Secondly, using quantum computing, we can significantly improve operations.

Quantum Key Distribution (QKD) is the most famous quantum communication protocol, which can achieve quantum key distribution (QKD) based on single optical paper, generating secure keys between two users. Combined with a case by case approach, unconditional and secure information transmission can be achieved. At the same time, quantum key distribution based on quantum entanglement can also be achieved.

In quantum computing, people use quantum bits to encode information, and use the quantum superposition principle to achieve ultrafast parallel computing, which can achieve exponential acceleration in principle. Large number decomposition algorithm is the most famous quantum algorithm at present. For example, to decompose a 300 bit natural number, it takes 150000 years to use a classical computer with trillions of operations per second, while a quantum computer with the same operation speed only takes one second. Therefore, quantum computer can be used in many fields such as cracking classical codes, weather forecasting, financial analysis and drug design. In order to achieve a generalized quantum communication network, we can use optical fibers to construct metropolitan quantum communication, and use quantum relays to achieve intercity quantum communication between two cities. With the further assistance of quantum satellite platforms, long-distance quantum communication can be achieved.

After nearly 20 years of effort, Chinese scientists have successfully developed the world's first quantum science satellite, Mozi, and successfully launched it in August 2016. In September 2017, the Beijing Shanghai trunk line, the backbone network network of long-distance optical fiber quantum communication, was officially opened. We have preliminarily verified the feasibility of establishing an integrated quantum network in principle based on the technology of the prototype of a wide area quantum communication network, combining the Mozi and the Beijing Shanghai mainline. In the field of quantum computing, it will take a long time to realize a universal quantum computer.

In order to ensure the healthy development of this field, the academic community has set three stages of development.

The first stage is to achieve the superiority of quantum computing. Quantum computing systems have far surpassed classical supercomputers in solving certain specific problems, demonstrating the superiority of quantum computing itself. The second stage is to build a dedicated quantum simulator to solve specific complex problems that classical computers cannot handle, such as high-temperature superconductivity mechanisms. The goal of the final third stage is to achieve universal programmable quantum computing with the help of quantum entanglement.

In 2020, we implemented the quantum computing prototype "Nine Chapters" with 76 photons. In solving the specific problem of Gaussian Persian sampling in Chapter Nine, the speed was 100000 times faster than the fastest classical supercomputer at that time. Afterwards, our system underwent continuous upgrades. Recently, we have implemented a prototype machine for calculating the number 933 quantum of light with 255 photons, which has a problem-solving ability that is 1000 trillion times faster than classic supercomputers.

In order to achieve global quantum communication in the future, we need to overcome the challenges currently faced by satellite quantum communication. One is that a single low orbit satellite cannot directly cover the world; Second, the current satellites can only work in the low area, and the corresponding solution is to launch multiple low orbit satellites to form an efficient Satellite Network. That is to say, based on the so-called quantum constellation, we can launch medium to high orbit satellites with longer transit times to distribute more keys.

A fundamental prerequisite for the implementation of these solutions is that satellites can operate in the background of solar radiation. In 2017, we had achieved ground experiments on long-distance free space quantum communication under sunlight, verifying that quantum communication is feasible all day, and achieving practical, low-cost, and lightweight micro quantum satellites.

The first micro/nano quantum satellite in the world, Jinan 1, was launched in July 2022, with a payload weight of only 20 kilograms, which has been significantly reduced compared to the Mozi spacecraft. We are currently developing the first mid to high orbit quantum satellite, with plans to launch around 2026. In addition to achieving quantum key distribution, this also provides a new platform for precise quantum measurement of medium to high orbit satellites.

We use medium to high orbit quantum satellites to achieve quantum entanglement distribution on the scale of ten thousand kilometers. In the future, we will use global entanglement distribution to entangle multiple atoms, thereby significantly improving the stability of atoms. At the same time, we plan to install an ultra high precision optical clock on a medium to high orbit satellite, which will have a stability of 10 to the 19th power, meaning its error will not exceed one second per year.

By utilizing high-precision optical clocks and transmission of high-precision optical frequency standards, global high-precision improvements can be achieved, which can increase the accuracy of microwave damage by 4 orders of magnitude compared to the current generation, providing corresponding technical support for the definition of the new generation of seconds. In outer space, due to the extremely weak noise caused by magnetic fields and Earth's gravity, the stability of the optical clock can reach a power of 10-21 in principle.

By utilizing ultra high precision optical clocks and ultra high precision optical frequency transmission, we can construct an interferometer in outer space and use it to test some basic principles of physics, including the detection of dark matter and gravitational waves.

In the field of quantum computing, we hope to achieve the relevant manipulation of hundreds of quantum bits in the next five years. Building a dedicated quantum simulator can help us understand some laws of complex physical systems, such as the mechanism of high temperature superconductivity, the quantum Hall effect, and so on. Through 10 to 15 years of efforts, we hope to be able to manipulate millions of quantum bits, realize quantum entanglement, and initially build a programmable universal quantum computer.