Mozi No. (English: Micius Satellite for Quantum Science Experiments[22]）Is the first space quantum science experiment satellite developed by China.
Mozi satellite project was developed byNational Space Science Center, Chinese Academy of Sciences(referred to as "Space Center")[14]The satellite is one of the first batch of scientific experiment satellites of the space science strategic leading science and technology special project of the Chinese Academy of Sciences. Its main scientific goal is to carry out satellite ground high-speed quantum key distribution experiments with the help of the satellite platform, and on this basis, carry out wide area quantum key network experiments, with a view to making a major breakthrough in the practical application of space quantum communication;Quantum entanglement distribution and quantum teleportation experiments are carried out at the spatial scale, and experimental research on the completeness test of quantum mechanics at the spatial scale is carried out[9][23]。
At 1:40 on August 16, 2016, China used it at Jiuquan Satellite Launch CenterLong March II DThe carrier rocket successfully launched the Mozi quantum science experiment satellite into the predetermined orbit[12]。
In May 2022, China's Mozi satellite will achieve a new record of 1200 km surface quantum state transmission[21]。
Chinese name
Mozi No[10]
Foreign name
Micius Satellite for Quantum Science Experiments[22]
In 1935,EinsteinIn the comment on quantum entanglement, it is called "ghost like action at a distance".According to quantum mechanics, no matter how far apart two particles in a quantum entangled state are, if the state of one particle is changed, the state of the other particle will change immediately.The correlation between these states does not need the force field or electric field in classical physics, and its correlation speed can also be considered to exceed the speed of light, which is called "quantum nonlocality".Einstein, as a representative of classical physics, expressed doubts about this, and felt that it would be "damned" if it could be established.
Since the 1930s, for nearly a hundred years, many theories of quantum mechanics have been continuously supported by experimental results, which has given birth to the atomic bomb, laser, nuclear magnetic resonance, global satellite positioning system and other major inventions, changed the whole world, and is considered to be the "first quantum revolution".The continuous research on Einstein's doubts has boosted the development of quantum control technology, spawned quantum information technology represented by quantum communication and quantum computing, and is considered to have started the "second quantum revolution"[26]。
Assumption of quantum communication
In 1984, two engineers from IBM, an American company, proposed a new confidential communication scheme, which uses the extreme characteristics of quantum physics to ensure that secrets are not stolen.In this scheme, the transmitter uses different polarization states of photons to represent the key, that is, different photons are emitted in a linear or diagonal polarization manner.If someone tries to eavesdrop, he can only intercept the photon measurement in the middle, and then send the same particle according to the measured value.Every time a photon is intercepted, one fourth of the eavesdroppers may be found.When the key length increases to 72 photons, the probability that the eavesdropper will not be found is only one in a billion.
In 1991, British scientists put forward a new idea: sending ciphertext using quantum entangled states.If A and B each hold a twin particle;As long as A operates the particles, B will get the same result.This is also the theoretical basis of today's quantum communication technology[27]。
Communication confidentiality is a key technology that all countries in the world strive to achieve.Quantum communication usually uses single photon as the physical carrier, and the most direct way is to transmit through optical fiber or near ground free space channel.How to achieve secure, long-distance and practical quantum communication is the biggest challenge in this field and the common goal of the international academic community for decades[11]。The massive dissemination of information is also full of risks of information leakage, and quantum science provides the "ultimate weapon" for information security[13]。
Development background
Quantum research
Quantum communication technology aims to realize the encoding, transmission, processing and decoding of information by using quantum states, especially the distribution of quantum keys by using quantum states (single photon states and entangled states).Among many communication methods, quantum communication technology is known as the "most difficult to decipher" encryption technology in history.The greatest advantage of quantum communication lies in its confidentiality. Many economic, scientific and military information is worthy of high confidentiality, so there are many potential users in quantum communication.The security of quantum communication is based on the basic principles of quantum physics.As the smallest particle of light, each light quantum has two characteristics of indivisibility and irreducibility when transmitting information. If there is eavesdropping, it will be detected and avoided by the information sender, so quantum communication ensures the security of information[10]。
In 1989, IBM laboratory made a small box called "Aunt Martha's coffin", in which the photon carried the key for 30 cm, proving that quantum secure communication is feasible.
In 1993, the British Ministry of Defence raised the record to 10km.However, it is difficult to obtain a single photon source and reduce the loss in photon signal transmission in practical applications[27]。
In outer space, there is almost no attenuation of light transmission in vacuum environment, and there is also no decoherence effect.Therefore, if a single photon or entangled photon pair can be sent out of the atmosphere, together with the on-board platform technology and the beam precise positioning technology, it is possible to achieve long-distance quantum communication in free space[16]。
Mozi Quantum Science Experiment Satellite isChinese Academy of SciencesOne of the first five scientific experiment satellites identified in the strategic leading science and technology project of space science aims to establish a remote quantum science experiment platform between satellites and the ground, and complete large-scale space quantum science experiments on this platform, with a view to achievingquantum mechanicsMajor breakthroughs in basic physics research and a series of scientific achievements with international visibilityQuantum communicationThe application of technology breaks through the limit of distance, develops to a deeper level, and promotes the ultimate realization of quantum communication in wide area and even in the world.At the same time, the project will provide a first-class test and application platform for the continuous innovation of various key technologies and devices of wide area quantum communication and engineering problems, promote the development of technologies such as space light tracking and pointing, space weak light detection, space ground high-precision time synchronization, small satellite platform high-precision attitude mechanism, high-speed single photon detection, and form independent core intellectual property rights[9]。
Mozi satellite development
Development process
In 2001, Pan Jianwei, 31, returned from Europe and set up a quantum information laboratory at the University of Science and Technology of China.
In 2003, when most people were still committed to the principle demonstration in the laboratory, Pan Jianwei's team proposed the preliminary idea of a "heaven and earth integrated" quantum communication network using satellites to achieve long-distance quantum entanglement distribution. The "quantum science experiment satellite" was the key node in this idea.Focusing on this vision, Pan Jianwei's team has made breakthroughs in free space quantum key distribution, quantum entanglement distribution and quantum teleportation experiments.
In 2005, Pan Jianwei's team realized the first quantum communication experiment of 13 km (greater than the vertical thickness of the atmosphere) free space bidirectional quantum entanglement distribution in the world, which confirmed that the quantum state of photons can be effectively maintained after penetrating the atmosphere, thus verifying the feasibility of satellite ground quantum communication[13]。
In 2006,University of Science and Technology of ChinaPan Jianwei's team realized the optical fiber quantum key distribution of more than 100 kilometers in the world for the first time using the decoy state scheme;American and Austrian scientists later did the same.
In 2008, Pan Jianwei's team invented a quantum repeater to enable the dying photons to transmit information to other photons, which was praised by Nature magazine as "clearing a block in quantum communication"[27]。
Pan Jianwei
In December 2009, the space science pilot project participatedStrategic leading science and technology projectImplementation plan review meeting, and ranked in the top three of 16 proposed special projects.
In 2010, the team realized the teleportation of 16 km quantum state based on quantum entanglement distribution for the first time in the world.
On December 23, 2011, the launch and mobilization meeting of the quantum science experiment satellite project was held in Beijing, marking that the quantum science experiment satellite officially entered the engineering development stage[16]；Subsequently asOne of the first batch of scientific experimental satellites of the space science pilot program of the Chinese Academy of Sciences, the quantum satellite project was officially established[13]。
In 2012, the joint research team of the Chinese Academy of Sciences led by Pan Jianwei realized the first 100 km two-way quantum entanglement distribution and quantum teleportation in Qinghai Lake, fully verifying the feasibility of using satellites to achieve quantum communication[28]。
On December 30, 2014, the quantum science experiment satellite passed the review of the initial sample to the normal sample stage, and officially entered the normal sample development stage.
On December 6, 2015, the quantum science experiment satellite system and the science application system completed the satellite ground optical docking test, which verified that the earth earth integration experiment system can meet the index requirements of scientific objectives[16]。
In August 2016, China's first quantum science experiment satellite was named "Mozi"[15], English:Micius Satellite for Quantum Science Experiments[22]；Abbreviation: Mozi or Micius;Also known as QSS (Quantum Science Satellite) or QUESS (Quantum Experiences at Space Scale)[29]。
R&D unit
The quantum satellite project is in the charge of the National Space Science Center of the Chinese Academy of Sciences;The University of Science and Technology of China is responsible for proposing scientific objectives and developing scientific application systems;Shanghai Institute of Microsatellite Innovation, Chinese Academy of Sciences, focuses on the development of satellite systems, and Shanghai Institute of Technical Physics, Chinese Academy of Sciences, cooperates with University of Science and Technology to develop the payload subsystem;The National Space Science Center of the Chinese Academy of Sciences takes the lead in the development, construction and operation of the ground support system;The Earth Observation and Digital Earth Science Center and other units participated[14]。
Pan Jianwei, Chief Scientist of Mozi Quantum Satellite[25](Physicist, academician of the Chinese Academy of Sciences,Academy of Sciences of Developing CountriesAcademician, Executive Vice President of University of Science and Technology of China[30]）
Chief designer of satellite system: Researcher Zhu Zhencai (Shanghai Micro Satellite Engineering Center, Chinese Academy of Sciences)
Deputy Chief Designer: Researcher Zhou Yilin (Shanghai Micro Satellite Engineering Center, Chinese Academy of Sciences)
According to the characteristics and actual needs of the quantum science experiment satellite, the Mozi satellite project has set up the overall engineering and six major systems, and the specific division of labor is as follows:
Satellite systemResponsible for the research and development of satellite platforms and payloads, including quantum key communicators, quantum entanglement transmitters, quantum entanglement sources and quantum experiment control and processors.
launch vehicle system Mainly responsible for the development and production of launch vehicles.
Launch site systemJiuquan Satellite Launch Center was selected to mainly undertake the test and launch tasks of carrier rocket and quantum science experiment satellite, and provide ground technical support and service support.
Measurement and control systemIt is responsible for providing measurement and control support for the active phase of the launch vehicle, transmitting the original telemetry data to the ground support system, receiving the scientific experiment data transmitted by the ground support system, and completing the uplink transmission and downlink reception of the data.
Ground support systemBe responsible for providing public support services such as experiment task operation control management, data receiving, pre-processing, management and archiving.
Scientific application systemResponsible for the formulation of the entire quantum science experiment satellite engineering science experiment plan, the implementation of scientific experiments, the processing, transmission, storage, management and release of scientific data and applications[32]。
Satellite platform
Sketch map of Mozi satellite
Mozi satellite system project includes the development of satellite platform and payload[9]。The total weight of Mozi satellite is 631kg[33]（《Journal of the Chinese Academy of Sciences》Introduction: 640kg[34]）The load weight is more than 200kg, but the long-term power consumption is less than 500W - it can be completely supplied by the battery.As a sun synchronous orbit satellite, the originally designed orbit height of the satellite was 600km, but it was running into the radiation belt of the earth.When doing simulation experiments, it was found that some devices had only one week of life under the bombardment of high-energy particles.Therefore, scientists lowered the orbital height to 500 kilometers to reduce the impact of about half of the high-energy particles in the universe.At the same time, scientists also came up with a way from the physical principle to finally make the device able to withstand the long-term bombardment of high-energy particles in orbit[33]。
Design parameters
Mozi Satellite Reference Data
Basic parameters
Satellite form
Cube
Satellite mass
640kg[34](631 kg[33]）
On-board load mass
More than 200 kg[33]
Satellite power consumption
Less than 500 watts[33]
Quantum key initial code generation rate
About 10kbps[34]
Design life
2 years[29][34]
Track parameters
Track height
500km[34]
Running track
Solar synchronous orbit (polar orbit)
auxiliary system
Scientific research equipment
Quantum key communicator, quantum entanglement transmitter, quantum entanglement source, quantum experiment control and processor[35]
Rocket carrier
Long March II Ding Rocket (CZ-2D)[34]
supporting facilities
One center (Hefei Quantum Science Experiment Center)
Four quantum communication ground stations (respectively located in Xinglong, Hebei, Urumqi, Xinjiang, Delingha, Qinghai, Lijiang, Yunnan)
1 quantum teleportation experimental station (Tibet Ali quantum teleportation experimental platform)[35]
Carrier rocket
Long March IID carrier rocket used for Mozi satellite launch[9]Is a normal temperature liquid two-stage liquid launch vehicle developed by Shanghai Aerospace Technology Research Institute affiliated to China Aerospace Science and Technology Corporation.The rocket was launched in February 1990Long March No.4 AThe rocket is formed by reducing three sub stages on the basis of the rocket and making adaptability improvement. It is mainly used to launch low earth orbit recoverable satellites and sun synchronous orbit, and has the characteristics of high reliability and good economy[36]。
Ground station
The supporting ground construction science application system of Mozi satellite includes one center - Quantum Science Experiment Center of Hefei University of Science and Technology of China;Four quantum communication ground stations include Beijing Xinglong Station, Yunnan Lijiang Station, Qinghai Delingha Station and Urumqi Nanshan Station[13][37]；One platform - the heaven and earth integrated quantum science experiment system with Ali Stealth Transmission Experiment Station as the core[9][13]。
Mozi Satellite Achieves 1200 km Transmission Record
One of the scientific objectives of Mozi is to carry out satellite ground high-speed quantum key distribution experiments, and on this basis, to carry out wide area quantum key network experiments, with a view to making a major breakthrough in the practical application of space quantum communication.This technological breakthrough not only enables China to directly provide high security level quantum communication guarantee for areas that cannot be covered by optical fiber, such as China's South China Sea islands, embassies and consulates abroad, ocean going ships, etc., but also provides reliable technical support for China's future construction of a global integrated quantum secure communication network.
At the same time, quantum satellites carry out quantum entanglement distribution and quantum teleportation experiments at the space scale. Through the satellite ground entanglement distribution of "Mozi", quantum entanglement can be established between two ground stations more than 1200 kilometers apart at a speed of 1 pair/second, which will enable mankind to carry out quantum science experiments at the space scale for the first time,And make technical preparations for the future testing of the basic principles of physics such as general relativity and quantum gravity in outer space, becoming another important contribution of China to the world in the field of basic physics[19]。
Quantum satellite is one of the first batch of scientific experimental satellites of the space science pilot program of the Chinese Academy of Sciences. Its main scientific objectives are: first, to carry out satellite ground high-speed quantum key distribution experiments with the help of satellite platforms, and on this basis, to carry out wide area quantum key network experiments, with a view to making a major breakthrough in the practical application of space quantum communication;The second is to carry out quantum entanglement distribution and quantum teleportation experiments at the spatial scale, and carry out experimental research on the completeness test of quantum mechanics at the spatial scale[9]。
Four experiments
Satellite ground high-speed quantum key distribution experiment
With the help of high-precision acquisition, tracking and aiming systems, the laboratory will conduct the generation and distribution of quantum keys between satellites and the ground based on decoy state on the basis of the establishment of ultra long distance quantum channels between the ground and satellites, and realize the absolutely safe confidential communication test between satellites and the ground with the quantum key as the core[9]So as to lay a technical foundation for the establishment of a global quantum communication network[32]。
Wide area quantum communication network experiment
In recent years, with the development of optical fiber quantum communication network technology, it has become possible to build a real wide area quantum communication network through the satellite ground quantum key distribution process[32]。On the basis of realizing high-speed satellite ground quantum key distribution, this experiment will combine with two optical ground stations and their two attached local optical fiber quantum communication networks to form a real wide area quantum communication network through satellite transit[9]。
Satellite ground quantum entanglement distribution experiment
In this experiment, the quantum entanglement light source on the satellite distributes entangled photons to two ground stations at the same time. After completing the quantum entanglement distribution, the entangled photons are simultaneously measured independently.Through the observation of thousands of kilometers quantum entangled states, the experimental research on the completeness test of quantum mechanics at the spatial scale is carried out[9]。
Quantum teleportation experiment of earth star
Quantum teleportation is a new way of communication and the basic process of quantum network and quantum computing[32]。With the help of quantum storage, this experiment will explore the true meaning of the distance between the satellite and the ground and the feasibility of quantum teleportation, and complete the experimental verification of quantum mechanical nonlocality under space like conditions[9]。
Schematic diagram of the experiment of realizing quantum secure communication based on entanglement without relay by Mozi number[38]
Equipment load
Mozi satellite platform payload includes: quantum key communicator, quantum entanglement transmitter, quantum entanglement source and quantum experiment control and processor[9][13]。
The quantum key distribution system on Mozi satellite weighs about 130 kg and requires 130 watts of power. Its scientific experimental tasks also include entanglement related quantum communication experiments, including bidirectional quantum entanglement distribution and quantum teleportation[39-40]。
The quantum entanglement source on the satellite, whose volume is only the size of the set-top box, plays a key role. It can generate entangled light, and is the source of various experiments carried out by the quantum satellite in the air.At ordinary times, the volume of the entanglement source in the laboratory is very large. Researchers not only miniaturized it, but also made it meet the requirements of space environment through a series of innovations, which is the first time in the world[13]。
Operation history
Announce
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Launch into orbit
On February 25, 2016, the quantum science experiment satellite project completed the large-scale system joint test.
On April 11, 2016, the Long March IID carrier rocket launching Mozi completed the factory review[16]。
At 1:40 a.m. on August 16, 2016, ChinaJiuquan Satellite Launch CenterLaunch the world's first quantum science experiment satellite "Mozi" with Long March II Dingyao 32 carrier rocket[12][41]。
Long March IID carrier rocket launches Mozi satellite
Space flight
Delivering Applications
On January 18, 2017, the world's first quantum science experiment satellite "Mozi" was officially delivered to the University of Science and Technology of China for use after successfully completing the 4-month in orbit test mission[19][42]；Same yearOn June 15, Chinese scientists reported in the American journal Science that the Chinese "Mozi" quantum satellite realized 1000 km quantum entanglement for the first time in the world, which means that quantum communication has taken a big step towards practical use[17][43-44]；On August 12 of the same year, "Mozi" achieved the latest achievement - the first successful 1000 km level satellite ground two-way quantum communication in the world, laying a solid scientific and technological foundation for building a global quantum secure communication network. Mozi quantum satellite completed all three preset scientific goals ahead of schedule[2][45-46]；On September 29 of the same year, the world's first quantum secure communication trunk line“Beijing Shanghai trunk line”Chinese scientists have successfully achieved intercontinental quantum secure communication by linking space and sky with the Mozi scientific experiment satellite.This marks that China has built the first prototype of a heaven and earth integrated wide area quantum communication network in the world, and has taken a solid step towards the realization of a global quantum secure communication network in the future[3]。
In January 2018, in China andAustriaThe first intercontinental distance of 7600km betweenQuantum key distributionThe shared key is used to realize encrypted data transmission and video communication.This achievement marks that "Mozi" has the ability to realize intercontinental quantum secure communication[4][18]。
Schematic diagram of Mozi's intercontinental quantum secure communication network[18]
On June 15, 2020, the Chinese Academy of Sciences announced that the "Mozi" quantum science experiment satellite achieved the first 1000 km quantum key distribution based on entanglement in the world.This experimental result not only increases the space distance of previous ground-based relayless quantum key distribution by an order of magnitude, but also ensures that even in the extreme case that the satellite is controlled by others, secure quantum key distribution can still be achieved through physical principles.International academic journals《natural》This achievement was published online at 23:00 on June 15, 2020 Beijing Time[5][38]。
On May 5, 2022, it was learned from the University of Science and Technology of China that Professor Pan Jianwei and his colleagues Peng Chengzhi, Chen Yuao, Yin Juan and others made important experimental progress in long-distance quantum state transmission by using the "Mozi" quantum science experiment satellite.The experiment broke the world record, and realized the remote transmission of quantum view between two ground stations 1200 kilometers away from the earth for the first time, which is an important step towards building a global quantum information processing and quantum communication network.Relevant research achievements will be published online in internationally renowned academic journals on April 26, 2022《Physical Review Letters 》On[20-21]。
Overdue work
On February 14, 2019, Chinese researchers said in Washington, the United States that the "Mozi" quantum science experiment satellite is expected to exceed its life expectancy, continue to work for at least two years, and carry out more international cooperation[6]。
Mozi satellite has very high requirements for precise control. During satellite flight, the two lasers carried by the satellite should aim at two ground stations thousands of kilometers apart, and simultaneously transmit quantum keys from left to right. The optical axis on the satellite and the optical axis of the ground telescope should always be precisely aligned, just like the "needle tip" on the satellite to the "wheat awn" on the ground.The scientific research team carried out various experiments to test the ability of ultra long distance "mobile targeting", and finally broke through the key technologies such as satellite ground optical path alignment. Through the two-level control of platform and load, the alignment accuracy can reach 10 times of that of ordinary satellites.
The laser station test has been done for the one station mode, but it has never been done internationally when one satellite is aimed at two ground stations.Mozi is also the first time in the world to achieve such high-precision tracking and ground station coordination[13]。
Communication trunk line
In 2017, the world's first quantum secure communication trunk line "Beijing Shanghai trunk line" was built."Mozi" joined hands with "Beijing Shanghai Trunk Line". Pan Jianwei, Chen Yuao, Peng Chengzhi, etc. from the University of Science and Technology of China, cooperated with Wang Jianyu Research Group of Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Jinan Institute of Quantum Technology and China Cable Television Network Co., Ltd. to build the world's first satellite ground quantum communication network.After more than two years of stability and security tests, multi-user quantum key distribution across 4600 kilometers has been realized.The whole network covers 32 nodes in four provinces and three cities in China, including four quantum metropolitan area networks in Beijing, Jinan, Hefei and Shanghai. It is connected to "Mozi" through two satellite ground stations, and has access to more than 150 users in finance, power, government and other industries[13][47]。
In August 2022, CCTV reported that the scientific research team of academician Pan Jianwei of the University of Science and Technology of China and the academician Wang Jianyu team of the Dean of Hangzhou Institute of Advanced Research of the University of Chinese Academy of Sciences passed the“Tiangong No.2”And compact quantum key distribution (QKD) terminals on four satellite ground stations, realizing the experimental demonstration of space ground quantum secure communication network.Relevant papers were published in the international academic journal Optics.The scientific research team established a quantum channel between the ground station and the target aircraft by cooperating with the high-precision automatic tracking system and the quantum key distribution terminal on the "Tiangong II", and carried out the air ground quantum sub key distribution test on this basis.
The "quantum key distribution test space terminal" aims to realize the world's first space ground quantum sub key distribution test based on manned space platform, and establishes a quantum channel between the ground station and the target aircraft, laying the foundation for the space ground quantum secure communication of manned space, as well as the construction of a practical space space integrated wide area quantum secure communication network in the future[48]。
When the Mozi quantum science experiment satellite passed through China, it simultaneously established optical links with two ground stations, Qinghai Delingha Station and Yunnan Lijiang Station. The total distance of quantum entangled photon pairs from the satellite to the two ground stations averaged 2000 kilometers, and the tracking accuracy reached 0.4 μ rad.The entanglement source load on the satellite generates 8 million entangled photon pairs per second. The optical link can be established at the speed of 1 pair per second between two stations over 1200 km on the ground. The transmission attenuation of the quantum entanglement is only one trillionth of the lowest loss ground fiber of the same length.Under the condition of closing the local loophole and the measurement selection loophole, the research team found that the experimental results obtained violated the Bell inequality with four times the standard deviation, that is, the quantum mechanical nonlocality test that strictly meets the "Einstein localization condition" was realized on a 1000 km spatial scale[28]。
The highly efficient satellite ground link collection technology developed by Mozi satellite application research results can reduce the weight of the quantum satellite payload from hundreds of kilograms to dozens of kilograms, and significantly reduce the weight of the ground receiving system from more than 10 tons to about 100 kilograms, so as to realize the miniaturization and transportability of the receiving system, which will help the scaleLay the foundation for commercial application[49]。
Mobility
On December 24, 2019,Jinan Institute of Quantum TechnologyThe deployment of the ground station was completed, and the docking test with the Mozi quantum science experiment satellite was successful, which marked the completion of the construction of China's first small mobile quantum satellite ground station in Jinan.Jinan Institute of Quantum Technology has started the project of miniaturized quantum communication satellite ground station system since 2019. The ground station on the top of the institute building is only about the size of a paint bucket, weighing more than 80 kilograms, and combined with the equipment of a 28cm telescope, it forms a movable quantum satellite ground stationJinan Institute of Quantum Technology is the first small mobile quantum satellite ground station in China.Subsequent R&D personnel successfully miniaturized the ground station, which not only greatly reduced the manufacturing cost, but also could be loaded on the vehicle for use anytime, anywhere, and could be promoted in industrialization[50]。
Optical interferometer
Quantum communication researchers use optical integrated bonding technology to achieve an optical interferometer with ultra-high stability, which can be stable for a long time without active closed-loop.With the breakthrough of this technology, combined with the quantum teleportation scheme based on the two-photon path polarization mixed entangled state, the remote quantum state transmission verification was completed between Lijiang Station in Yunnan Province and Delingha Ground Station.Six typical quantum states were verified in the experiment, and the transmission fidelity exceeded the classical limit.The distance of 1000 kilometers is a new record of quantum state transmission on the surface by 2022[20-21]。
New paint
Mozi satellite
All flexible film thermal control coatings and bright oxidation thermal control coatings of aluminum alloy for the lower skirt of Mozi satellite have been successfully applied.
Flexible film thermal control coating
Shanghai Silicate Institute has undertaken the research and development of flexible film thermal control coating materials, including "wide conductive F46 film silver plated secondary surface mirror" and "wide anti-static PI film aluminum plated secondary surface mirror", which provide an important guarantee for the normal on orbit operation of satellites.The wide conductive F46 film silver plated secondary surface mirror used is a new flexible film secondary surface mirror with low radiation absorption ratio, which is successfully developed on the basis of the wide anti-static F46 film silver plated secondary surface mirror, and has more reliable space anti-static performance.The institute is the only scientific research institute in China that has mastered the development technology of the wide anti-static F46 silver plated secondary surface mirror, and it is also one of the two suppliers that can provide this type of thermal control coating in batches all over the world[51]。
Aluminum alloy bright oxidation thermal control coating for lower skirt
Shanghai Silicate Institute undertook the research and development of bright oxidation thermal control coating for Mozi satellite, and used chemical methods to in-situ grow a layer of thermal control coating material with low solar absorption ratio and high infrared emissivity on the surface of the lower skirt of the satellite.The thermal control coating developed this time has broken through the difficulties of coating preparation with high requirements for thermal radiation index and large size and complex shape of satellite skirt.The obtained coating is composed of aluminum oxide, which is characterized by high hardness and good space stability, providing important guarantee for the separation of satellite and launch vehicle in orbit and long-term normal operation in orbit[51]。
Follow up Outlook
China plans to launch "Mozi II" and "Mozi III" later.As a single LEO satellite cannot cover the world, and because of the strong sunlight background, the satellite ground quantum communication can only be carried out at night by 2022.To achieve efficient global quantum communication, a satellite network is also needed.According to the plan, a "bright star cluster" composed of dozens of quantum satellites will "hand in hand" with the ground quantum communication trunk line to support the "heaven and earth integrated" quantum communication network.
By 2030 or so, China will strive to take the lead in building a global wide area quantum secure communication network.On this basis, we will build a "quantum internet" with sufficient information security to form a complete quantum communication industry chain and the next generation of national sovereign information security ecosystem[13]。
Schematic Diagram of Mozi's Scientific Achievements
Honors won
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Honor award
At the end of 2016, the United States《Scientific Americans》In the selection, "Mozi" quantum satellite, as the only innovative technology born outside the United States, was selected as the "Top Ten Innovative Technologies that Change the World" in 2016[10]。
On January 31, 2019,American Association for the Advancement of ScienceIt was announced that the Mozi quantum science experiment satellite scientific research team led by Professor Pan Jianwei of the University of Science and Technology of China was awarded the 2018 Cleveland Prize, in recognition of the team's contribution to promoting large-scale quantum communication experiment research by achieving 1000 km level satellite ground two-way quantum entanglement distribution[1]。
Cultural characteristics
Satellite naming
On August 15, 2016, Pan Jianwei, chief scientist of the Chinese Quantum Science Experiment Satellite and academician of the Chinese Academy of Sciences, revealed in an interview with the media at the Jiuquan Satellite Launch Center that the quantum science experiment satellite has been officially named "Mozi".This is the first time that the name of quantum satellite has been published.Pan Jianwei said: "The name of the satellite comes from the Chinese scientists, which reflects China's cultural self-confidence."
Philosopher, founder of Mohist SchoolMoziHe is also a great scientist《Ink classics》The first "pinhole imaging" experiment in the world was recorded in, which explained the reason for pinhole inversion.Mozi proposed that light travels along a straight line, which is the first time to explain that light travels in a straight line - this is also a very important principle in optics.The use of "Mozi" to name the quantum satellite is consistent with the meaning of the project itself, and also reflects China's cultural confidence[15]。
Schematic diagram of Mozi satellite communication test
Overall evaluation
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Mozi and Ali quantum teleportation experimental platform establish a heaven and earth link[19]
The successful launch of Mozi will enable China to realize quantum communication between satellite and ground for the first time in the world, and build a quantum secure communication and scientific experiment system integrating heaven and earth[12]。The successful launch and in orbit operation of the quantum satellite will help China maintain and expand its international leading position in the overall level of the practical application of quantum communication technology, achieve a leap forward improvement in national information security and information technology, and is expected to promote Chinese scientists to make major breakthroughs in the forefront of quantum science,It is of great significance to promote the sustainable development of China's space science satellite series[14]。（Comments on www.gov.cn and xinhuanet）
Boston UniversityAlexander Sergienko, a quantum physicist based in Geneva, said: "This is really exciting, because it is the first time to carry out such experiments, so it is of great significance to the whole world. The competition of quantum communication began when European researchers first demonstrated quantum key distribution at the bottom of Lake Geneva in 1995.Since then, countries such as the United Kingdom, the United States, Japan and China have been exploring the quantum communication network between cities, and this competition has entered space from the ground, because satellites can connect different cities far away.China has taken the lead in launching quantum satellites. "
University of CambridgeQuantum physicsProfessor Adrian Kent said, "I am very excited about China's launch of quantum satellites." He believed that this was the "first step" to build a global secure communication network using quantum technology[7]。
Benefiting from the absolute security of quantum secure communication, quantum communication is not only used for people's daily communication, but also for energy supply such as water, electricity, gas, and communication guarantee of livelihood network infrastructure. It can also be used in national defense, finance, commerce, and other fields, which is bound to bring great changes to the industry and scientific and technological circles[8]。Mozi has also opened the door to global quantum communication, space quantum physics and quantum gravity experiment testing, which has helped China seize the commanding heights of quantum science and technology innovation in the world, become a benchmark for international peers, and realized the transformation of "leader".Quantum information technology represented by Mozi satellite system is a strategic and basic frontier scientific and technological innovation field, which can break through the bottleneck of classical technology in ensuring information security, improving computing speed, improving measurement accuracy, etc. It is related to the trend of global scientific and technological revolution and industrial change, and is the focus of international competition.Quantum communication is expected to solve the security problem of information transmission in finance, government affairs, commerce and other fields[52]。（Comments of Chinese Academy of Sciences and University of Science and Technology of China）
