China Quantum Communiations Technology: Cryptography, Radar, Satellite, Teleportation, Network
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15 Jun 2020 | 15:00 GMT
Quantum Satellite Links Extend More Than 1,000 Kilometers
New system one step closer to practical quantum cryptography
By Charles Q. Choi
A space-based, virtually unhackable quantum Internet may be one step closer to reality due to satellite experiments that linked ground stations more than 1,000 kilometers apart, a new study finds.
...
Quantum Satellite Links Extend More Than 1,000 Kilometers - IEEE Spectrum
Quantum Satellite Links Extend More Than 1,000 Kilometers
New system one step closer to practical quantum cryptography
By Charles Q. Choi
A space-based, virtually unhackable quantum Internet may be one step closer to reality due to satellite experiments that linked ground stations more than 1,000 kilometers apart, a new study finds.
...
Quantum Satellite Links Extend More Than 1,000 Kilometers - IEEE Spectrum
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Scientists set milestone in quantum tech
By Zhang Zhihao | China Daily | Updated: 2020-06-16 09:20
Quantum scientist Pan Jianwei works in the quantum lab of the Univerisity of Science and Technology of China on April 20, 2017. [Photo/Xinhua]
Chinese scientists have achieved the world's first quantum key distribution over 1,120 kilometers without relying on any intermediate security relays, according to a study published in the journal Nature on Monday.
Experts said this represents a major milestone in building a practical global-scale, ultra-secure quantum internet, but the actual technology might still be years away.
Quantum key distribution, known as QKD, is a technique used to achieve secure communication that uses cryptographic protocols based on the laws of quantum mechanics. Today's QKD is mostly conducted through optical fibers on the ground, with few exceptions using quantum satellites.
These protocols can generate secret security keys that enable more secured data transfer between devices by allowing authorities to spot eavesdroppers trying to intercept communications.
"QKD is theoretically highly secured. But in reality, imperfections in equipment such as photon sources and detectors may lead to security risks," said Pan Jianwei, noted quantum physicist and the lead scientist behind the study.
Moreover, QKD via optical fibers are susceptible to interference and cannot be sent over ultralong distance without relying on intermediate repeaters to boost the signals, he said.
To tackle these issues, Pan and his team tested a new QKD protocol method that uses satellites instead of ground-based relays.
They achieved this by using China's quantum science satellite Micius to send a secret key at the rate of 0.12 bits per second between the ground stations at Delingha and Urumqi, separated by around 1,120 kilometers.
Peer-reviewed comments called the study a "groundbreaking experiment", and a "significant step toward establishing a global network for QKD, and more generally, a quantum internet for quantum communication."
Gilles Brassard, one of the founders of quantum cryptography, said if the technology for secured, long distance quantum communication finally arrives, "this would achieve the Holy Grail that all cryptographers have been dreaming of for thousands of years."
Wang Jianyu, a researcher from the Shanghai Institute of Technological Physics of the Chinese Academy of Sciences, said now that the study has proved that the new technique is technically feasible, the next step should be increasing its communication capacity to make it useful.
"It is still too soon to say when the technology will reach the mass market," he said. "But in the next three to five years, we might see another leap in this method's efficiency, and that might be enough to support a nation's financial and security communication needs."
Scientists set milestone in quantum tech
By Zhang Zhihao | China Daily | Updated: 2020-06-16 09:20
Chinese scientists have achieved the world's first quantum key distribution over 1,120 kilometers without relying on any intermediate security relays, according to a study published in the journal Nature on Monday.
Experts said this represents a major milestone in building a practical global-scale, ultra-secure quantum internet, but the actual technology might still be years away.
Quantum key distribution, known as QKD, is a technique used to achieve secure communication that uses cryptographic protocols based on the laws of quantum mechanics. Today's QKD is mostly conducted through optical fibers on the ground, with few exceptions using quantum satellites.
These protocols can generate secret security keys that enable more secured data transfer between devices by allowing authorities to spot eavesdroppers trying to intercept communications.
"QKD is theoretically highly secured. But in reality, imperfections in equipment such as photon sources and detectors may lead to security risks," said Pan Jianwei, noted quantum physicist and the lead scientist behind the study.
Moreover, QKD via optical fibers are susceptible to interference and cannot be sent over ultralong distance without relying on intermediate repeaters to boost the signals, he said.
To tackle these issues, Pan and his team tested a new QKD protocol method that uses satellites instead of ground-based relays.
They achieved this by using China's quantum science satellite Micius to send a secret key at the rate of 0.12 bits per second between the ground stations at Delingha and Urumqi, separated by around 1,120 kilometers.
Peer-reviewed comments called the study a "groundbreaking experiment", and a "significant step toward establishing a global network for QKD, and more generally, a quantum internet for quantum communication."
Gilles Brassard, one of the founders of quantum cryptography, said if the technology for secured, long distance quantum communication finally arrives, "this would achieve the Holy Grail that all cryptographers have been dreaming of for thousands of years."
Wang Jianyu, a researcher from the Shanghai Institute of Technological Physics of the Chinese Academy of Sciences, said now that the study has proved that the new technique is technically feasible, the next step should be increasing its communication capacity to make it useful.
"It is still too soon to say when the technology will reach the mass market," he said. "But in the next three to five years, we might see another leap in this method's efficiency, and that might be enough to support a nation's financial and security communication needs."
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Academician and quantum physicist - Pan Jianwei in the picture of the article above, is the second biggest shareholder, with his holding now worth more that 2.4 billion yuan.
QuantumCTek Sets China Stock Record, Rallying Up to 1,000% on First Trading Day
XU WEI
DATE: 18 HOURS AGO / SOURCE: YICAI
QuantumCTek Sets China Stock Record, Rallying Up to 1,000% on First Trading Day
(Yicai Global) July 9 -- QuantumCTek, a developer of quantum communications products, notched up China’s biggest ever first-day trading gain by surging as much as 1,000 percent in its Shanghai market debut.
Shares of QuantumCTek [SHA: 688027] closed at CNY370.45 (USD53.04) on the Nasdaq-style Star market, almost 924 percent higher than their initial offering price of CNY36.18 (USD5.18) each.
The previous record holder was Tinavi Medical Technologies, a Beijing-based medical devices maker, which shot up 614 percent in its Star Market debut just two days ago.
QuantumCTek’s stellar market entry comes amid a bull run. The CSI 300 index of Shanghai and Shenzhen-traded shares, a key gauge of mainland equities, climbed almost 7.7 percent last month and had climbed almost 14.7 percent this month as of yesterday.
Net profit at Hefei-based QuantumCTek slid 32 percent to CNY49.3 million (USD7.06 million) last year from 2018, after dipping 2.5 percent that year to CNY72.5 million. It had a net loss of CNY8.8 million in the first quarter of this year on a 5.5 percent decline in operating revenue from a year earlier to CNY1.5 million.
Editor: Peter Thomas
QuantumCTek Sets China Stock Record, Rallying Up to 1,000% on First Trading Day
XU WEI
DATE: 18 HOURS AGO / SOURCE: YICAI
(Yicai Global) July 9 -- QuantumCTek, a developer of quantum communications products, notched up China’s biggest ever first-day trading gain by surging as much as 1,000 percent in its Shanghai market debut.
Shares of QuantumCTek [SHA: 688027] closed at CNY370.45 (USD53.04) on the Nasdaq-style Star market, almost 924 percent higher than their initial offering price of CNY36.18 (USD5.18) each.
The previous record holder was Tinavi Medical Technologies, a Beijing-based medical devices maker, which shot up 614 percent in its Star Market debut just two days ago.
QuantumCTek’s stellar market entry comes amid a bull run. The CSI 300 index of Shanghai and Shenzhen-traded shares, a key gauge of mainland equities, climbed almost 7.7 percent last month and had climbed almost 14.7 percent this month as of yesterday.
Net profit at Hefei-based QuantumCTek slid 32 percent to CNY49.3 million (USD7.06 million) last year from 2018, after dipping 2.5 percent that year to CNY72.5 million. It had a net loss of CNY8.8 million in the first quarter of this year on a 5.5 percent decline in operating revenue from a year earlier to CNY1.5 million.
Editor: Peter Thomas
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Chinese scientists implement the world’s first quantum secure direct communication system
Source: Global Times Published: 2020/9/20 13:57:20
photo: web
A Chinese research team has implemented the world's first quantum secure direct communication (QSDC) system. The breakthrough provides a promising solution to counter threats in the area of communication security.
Beijing Academy of Quantum Information Sciences revealed at the 2020 ZGC Forum on Saturday that they have implemented the world's first QSDC system.
The present system can operate with a communication rate of 4kb/s at a distance of 10 kilometers, bringing QSDC further toward practical applications.
QSDC was proposed by Long Guilu, adjunct member of Beijing Academy of Quantum Information Sciences in 2000.
As an important branch of quantum communication, secret information can be directly transmitted without key distribution, which eliminates further security loopholes associated with key storage and attacks, according to Gui.
Source: Global Times Published: 2020/9/20 13:57:20
A Chinese research team has implemented the world's first quantum secure direct communication (QSDC) system. The breakthrough provides a promising solution to counter threats in the area of communication security.
Beijing Academy of Quantum Information Sciences revealed at the 2020 ZGC Forum on Saturday that they have implemented the world's first QSDC system.
The present system can operate with a communication rate of 4kb/s at a distance of 10 kilometers, bringing QSDC further toward practical applications.
QSDC was proposed by Long Guilu, adjunct member of Beijing Academy of Quantum Information Sciences in 2000.
As an important branch of quantum communication, secret information can be directly transmitted without key distribution, which eliminates further security loopholes associated with key storage and attacks, according to Gui.
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China speeds up construction of space-ground integrated quantum network
By Pan Xutao (People's Daily Overseas Edition) 09:32, November 12, 2020
Photo taken on Nov. 9 shows the construction site of the quantum information and quantum technology innovation research institute of the Chinese Academy of Sciences (CAS) in the High-tech Industry Development Zone of Hefei, east China''s Anhui province. (People’s Daily Online/Ruan Xuefeng)
Origin Quantum Computing Technology Co., Ltd., one of the over 20 quantum-related companies densely distributed along the 2,000-meter-long “quantum avenue”, or Yunfei Road, in the High-tech Industry Development Zone of Hefei, east China’s Anhui province, has almost been overwhelmed by various capital that came to it in the recent month.
“More than 30 investment institutions came to us, and eventually we chose 11 of them,” said Zhang Hui, vice president of the company. In the past, the man had to toss about the country for financing.
Government departments at different levels have also reached the company to offer help, according to Zhang.
“Many government departments visited our company for investigation and inspection, aiming to discuss and formulate industrial policies and help us solve practical difficulties,” Zhang noted, who has been invigorated by such efforts.
On Oct. 16, the Political Bureau of the Communist Party of China (CPC) Central Committee held the 24th group study session on the research and application of quantum science and technology.
The session has promoted strategic planning and forward-looking layout for the development of quantum science and technology in China, signaling an important period of development opportunities for the application of quantum science and technology, according to Zhang.
The applications of quantum science and technology specifically involve three fields: quantum communication, quantum computation and quantum precision measurement.
China is among the global leaders in the field of quantum communication.
According to the Ministry of Science and Technology (MOST), China has made a great number of major new and high-tech achievements during the 13th Five-Year Plan period (2016-2020).
Experiments including the quantum science satellite Mozi and the quantum communication line between Beijing and Shanghai conducted by Chinese scientists have enabled the country to build the prototype of the first space-ground integrated quantum communication network, said Qin Yong, director-general of the Department of High and New Technology of the MOST at a press conference held by the State Council Information Office on Oct. 21.
Quantum computation is also an important field for applications of quantum science and technology.
On the whole, China is at the same level with developed countries in the field of quantum computation, according to Pan Jianwei, executive vice president of the University of Science and Technology of China (USTC) and academician at the Chinese Academy of Sciences (CAS).
The research and development of quantum computers is a hotspot of the current international competition in the area of science and technology.
At the end of 2019, Chinese scientists teamed up with their counterparts from Germany and the Netherlands and realized the Boson sampling quantum computation by feeding 20 photons into a 60×60 mode interferometer for the first time in the world, setting new world records in four key indicators.
There is still a gap between China and developed countries in the field of quantum precision measurement, but the country is seeing rapid development in the field, Pan said.
In October this year, the USTC announced that its research team, in cooperation with scientists from the U.S. and Germany, observed strength compression on single-photon source devices with high purity, high indistinguishability and high efficiency.
The discovery, while marking the first time that scientists directly observed strength compression in the system after 20 years of efforts, has laid a foundation for single-photon sources-based quantum precision measurement and represented an important progress in the field of quantum precision measurement.
At present, theoretical research results in quantum science and technology are adapted for practical use and engineering at a faster pace, while more and more enterprises are joining in the force driving the development of quantum science and technology.
Among the three major fields for the application of quantum science and technology, quantum communication has witnessed the most commercial results and the birth of a lot of upstream and downstream firms in the field.
Compared with quantum communication, the value of quantum computation is yet to be brought into full play through practical applications.
However, quantum computation is regarded as the key engine of the next generation of information revolution, as it enjoys great prospects in such areas as cryptanalysis, weather forecast, oil exploration, as well as drug design.
Although it takes time to realize large-scale application of quantum computation, many companies are speeding up efforts in the field to seize the initiative in the development of relevant applications.
Back in 2015, Aliyun, Alibaba’s cloud computing subsidiary, joined hands with the CAS to start exploration of quantum computation. Later, Alibaba established a quantum computing lab.
In September 2019, the quantum computing lab completed the development task of the first controllable quantum bit.
Quantum precision measurement seems more mysterious compared with quantum communication and quantum computation.
Quantum measurement can help precisely monitor electric current and voltage in power grid. When used in prospection, quantum measurement can enable people to measure the geological composition of the surrounding area during well drilling. In addition, quantum measurement can help conduct accurate analysis of the content of trace substances in blood.
By Pan Xutao (People's Daily Overseas Edition) 09:32, November 12, 2020
Origin Quantum Computing Technology Co., Ltd., one of the over 20 quantum-related companies densely distributed along the 2,000-meter-long “quantum avenue”, or Yunfei Road, in the High-tech Industry Development Zone of Hefei, east China’s Anhui province, has almost been overwhelmed by various capital that came to it in the recent month.
“More than 30 investment institutions came to us, and eventually we chose 11 of them,” said Zhang Hui, vice president of the company. In the past, the man had to toss about the country for financing.
Government departments at different levels have also reached the company to offer help, according to Zhang.
“Many government departments visited our company for investigation and inspection, aiming to discuss and formulate industrial policies and help us solve practical difficulties,” Zhang noted, who has been invigorated by such efforts.
On Oct. 16, the Political Bureau of the Communist Party of China (CPC) Central Committee held the 24th group study session on the research and application of quantum science and technology.
The session has promoted strategic planning and forward-looking layout for the development of quantum science and technology in China, signaling an important period of development opportunities for the application of quantum science and technology, according to Zhang.
The applications of quantum science and technology specifically involve three fields: quantum communication, quantum computation and quantum precision measurement.
China is among the global leaders in the field of quantum communication.
According to the Ministry of Science and Technology (MOST), China has made a great number of major new and high-tech achievements during the 13th Five-Year Plan period (2016-2020).
Experiments including the quantum science satellite Mozi and the quantum communication line between Beijing and Shanghai conducted by Chinese scientists have enabled the country to build the prototype of the first space-ground integrated quantum communication network, said Qin Yong, director-general of the Department of High and New Technology of the MOST at a press conference held by the State Council Information Office on Oct. 21.
Quantum computation is also an important field for applications of quantum science and technology.
On the whole, China is at the same level with developed countries in the field of quantum computation, according to Pan Jianwei, executive vice president of the University of Science and Technology of China (USTC) and academician at the Chinese Academy of Sciences (CAS).
The research and development of quantum computers is a hotspot of the current international competition in the area of science and technology.
At the end of 2019, Chinese scientists teamed up with their counterparts from Germany and the Netherlands and realized the Boson sampling quantum computation by feeding 20 photons into a 60×60 mode interferometer for the first time in the world, setting new world records in four key indicators.
There is still a gap between China and developed countries in the field of quantum precision measurement, but the country is seeing rapid development in the field, Pan said.
In October this year, the USTC announced that its research team, in cooperation with scientists from the U.S. and Germany, observed strength compression on single-photon source devices with high purity, high indistinguishability and high efficiency.
The discovery, while marking the first time that scientists directly observed strength compression in the system after 20 years of efforts, has laid a foundation for single-photon sources-based quantum precision measurement and represented an important progress in the field of quantum precision measurement.
At present, theoretical research results in quantum science and technology are adapted for practical use and engineering at a faster pace, while more and more enterprises are joining in the force driving the development of quantum science and technology.
Among the three major fields for the application of quantum science and technology, quantum communication has witnessed the most commercial results and the birth of a lot of upstream and downstream firms in the field.
Compared with quantum communication, the value of quantum computation is yet to be brought into full play through practical applications.
However, quantum computation is regarded as the key engine of the next generation of information revolution, as it enjoys great prospects in such areas as cryptanalysis, weather forecast, oil exploration, as well as drug design.
Although it takes time to realize large-scale application of quantum computation, many companies are speeding up efforts in the field to seize the initiative in the development of relevant applications.
Back in 2015, Aliyun, Alibaba’s cloud computing subsidiary, joined hands with the CAS to start exploration of quantum computation. Later, Alibaba established a quantum computing lab.
In September 2019, the quantum computing lab completed the development task of the first controllable quantum bit.
Quantum precision measurement seems more mysterious compared with quantum communication and quantum computation.
Quantum measurement can help precisely monitor electric current and voltage in power grid. When used in prospection, quantum measurement can enable people to measure the geological composition of the surrounding area during well drilling. In addition, quantum measurement can help conduct accurate analysis of the content of trace substances in blood.
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Securing a Wireless Link with Quantum Physics
Researchers shared tamper-proof quantum information across nearly 20 km of open air in an urban environment.
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JANUARY 6, 2021
The world's first integrated quantum communication network
by University of Science and Technology of China
Chinese scientists have established the world's first integrated quantum communication network, combining over 700 optical fibers on the ground with two ground-to-satellite links to achieve quantum key distribution over a total distance of 4,600 kilometers for users across the country. Credit: University of Science and Technology of China
Chinese scientists have established the world's first integrated quantum communication network, combining over 700 optical fibers on the ground with two ground-to-satellite links to achieve quantum key distribution over a total distance of 4,600 kilometers for users across the country. The team, led by Jianwei Pan, Yuao Chen, Chengzhi Peng from the University of Science and Technology of China in Hefei, reported in Nature their latest advances towards the global, practical application of such a network for future communications.
Unlike conventional encryption, quantum communication is considered unhackable and therefore the future of secure information transfer for banks, power grids and other sectors. The core of quantum communication is quantum key distribution (QKD), which uses the quantum states of particles—e.g. photons—to form a string of zeros and ones, while any eavesdropping between the sender and the receiver will change this string or key and be noticed immediately. So far, the most common QKD technology uses optical fibers for transmissions over several hundred kilometers, with high stability but considerable channel loss. Another major QKD technology uses the free space between satellites and ground stations for thousand-kilometer-level transmissions. In 2016, China launched the world's first quantum communication satellite (QUESS, or Mozi/Micius) and achieved QKD with two ground stations which are 2,600 km apart. In 2017, an over 2,000-km long optical fiber network was completed for QKD between Beijing and Shanghai.
Using trusted relays, the ground-based fiber network and the satellite-to-ground links were integrated to serve more than 150 industrial users across China, including state and local banks, municipal power grids, and e-government websites. "Our work shows that quantum communication technology is sufficiently mature for large-scale practical applications," said Jianwei Pan, Professor of USTC. Similarly, a global quantum communication network can be established if national quantum networks from different countries are combined, and if universities, institutions and companies come together to standardize related protocols, hardware, etc., he added.
In the last couple of years, the team extensively tested and improved the performance of different parts of the integrated network. For instance, with an increased clock rate and more efficient QKD protocol, the satellite-to-ground QKD now has an average key generation rate of 47.8 kilobits per second, which is 40 times higher than the previous rate. The researchers have also pushed the record for ground-based QKD to beyond 500 km using a new technology called twin-field QKD (TF-QKD).
Next up, the team will further expand the network in China and with their international partners from Austria, Italy, Russia and Canada. They also aim to develop small-scale, cost-efficient QKD satellites and ground-based receivers, as well as medium and high earth orbit satellites to achieve all-time, ten-thousand-km-level QKD.
phys.org
The world's first integrated quantum communication network
by University of Science and Technology of China
Chinese scientists have established the world's first integrated quantum communication network, combining over 700 optical fibers on the ground with two ground-to-satellite links to achieve quantum key distribution over a total distance of 4,600 kilometers for users across the country. The team, led by Jianwei Pan, Yuao Chen, Chengzhi Peng from the University of Science and Technology of China in Hefei, reported in Nature their latest advances towards the global, practical application of such a network for future communications.
Unlike conventional encryption, quantum communication is considered unhackable and therefore the future of secure information transfer for banks, power grids and other sectors. The core of quantum communication is quantum key distribution (QKD), which uses the quantum states of particles—e.g. photons—to form a string of zeros and ones, while any eavesdropping between the sender and the receiver will change this string or key and be noticed immediately. So far, the most common QKD technology uses optical fibers for transmissions over several hundred kilometers, with high stability but considerable channel loss. Another major QKD technology uses the free space between satellites and ground stations for thousand-kilometer-level transmissions. In 2016, China launched the world's first quantum communication satellite (QUESS, or Mozi/Micius) and achieved QKD with two ground stations which are 2,600 km apart. In 2017, an over 2,000-km long optical fiber network was completed for QKD between Beijing and Shanghai.
Using trusted relays, the ground-based fiber network and the satellite-to-ground links were integrated to serve more than 150 industrial users across China, including state and local banks, municipal power grids, and e-government websites. "Our work shows that quantum communication technology is sufficiently mature for large-scale practical applications," said Jianwei Pan, Professor of USTC. Similarly, a global quantum communication network can be established if national quantum networks from different countries are combined, and if universities, institutions and companies come together to standardize related protocols, hardware, etc., he added.
In the last couple of years, the team extensively tested and improved the performance of different parts of the integrated network. For instance, with an increased clock rate and more efficient QKD protocol, the satellite-to-ground QKD now has an average key generation rate of 47.8 kilobits per second, which is 40 times higher than the previous rate. The researchers have also pushed the record for ground-based QKD to beyond 500 km using a new technology called twin-field QKD (TF-QKD).
Next up, the team will further expand the network in China and with their international partners from Austria, Italy, Russia and Canada. They also aim to develop small-scale, cost-efficient QKD satellites and ground-based receivers, as well as medium and high earth orbit satellites to achieve all-time, ten-thousand-km-level QKD.
The world's first integrated quantum communication network
Chinese scientists have established the world's first integrated quantum communication network, combining over 700 optical fibers on the ground with two ground-to-satellite links to achieve quantum key distribution over a total distance of 4,600 kilometers for users across the country. The team...
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PhysOrg Physics News @physorg_physics
Researchers realize efficient generation of high-dimensional quantum #teleportation
Researchers realize efficient generation of high-dimensional quantum #teleportation
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According to the University of Science and Technology of China (USTC), important new progress has been made in the research of quantum communication and quantum networks. Taking advantage of high-quality entangled photon pair sources, scientists have realized long-distance quantum entanglement purification through 11 km fiber for the first time, with purification efficiency more than 6,000 times higher than the international level.
The work was conducted by a research group headed by Li Chuanfeng and Liu Biheng as part of Academician Guo Guangcan's team at USTC, in cooperation with researchers from Nanjing University of Posts and Telecommunications. The results were published in the internationally renowned journal Physical Review Letters on Jan. 8.
High-quality long-distance entanglement is essential for both quantum communication and scalable quantum networks. The previous significant entanglement purification experiments require two pairs of low-quality entangled states and were demonstrated in tabletop.
The USTC researchers proposed a high-efficiency and long-distance entanglement purification using only one pair of hyperentangled state. In their studies, one pair of polarization spatial-mode hyperentanglement was distributed over 11 km multicore fiber (noisy channel).
The results show that after purification, the fidelity of polarization entanglement increased from 0.771 to 0.887. Moreover, by using one pair of hyperentanglement, the total purification efficiency can be estimated as 6.6×103 times the experiment using two pairs of entangled states with spontaneous parametric down-conversion sources.
The research results provide important technical support for the realization of highly efficient quantum relay in the future.
The work was conducted by a research group headed by Li Chuanfeng and Liu Biheng as part of Academician Guo Guangcan's team at USTC, in cooperation with researchers from Nanjing University of Posts and Telecommunications. The results were published in the internationally renowned journal Physical Review Letters on Jan. 8.
High-quality long-distance entanglement is essential for both quantum communication and scalable quantum networks. The previous significant entanglement purification experiments require two pairs of low-quality entangled states and were demonstrated in tabletop.
The USTC researchers proposed a high-efficiency and long-distance entanglement purification using only one pair of hyperentangled state. In their studies, one pair of polarization spatial-mode hyperentanglement was distributed over 11 km multicore fiber (noisy channel).
The results show that after purification, the fidelity of polarization entanglement increased from 0.771 to 0.887. Moreover, by using one pair of hyperentanglement, the total purification efficiency can be estimated as 6.6×103 times the experiment using two pairs of entangled states with spontaneous parametric down-conversion sources.
The research results provide important technical support for the realization of highly efficient quantum relay in the future.
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IEEE Spectrum @IEEESpectrum
The latest #quantum #cryptography system has notched an open-air milestone. Chinese researchers have hardened it such that receiving stations can even be hacked, and the cryptographic key will still get through, undisturbed.
11:05 PM · Jan 19, 2021
The latest #quantum #cryptography system has notched an open-air milestone. Chinese researchers have hardened it such that receiving stations can even be hacked, and the cryptographic key will still get through, undisturbed.
11:05 PM · Jan 19, 2021
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Global Times @globaltimesnews
China state-affiliated media
#Exclusive: Chinese scientists achieve #quantum information masking in lab, enabling non-copyable keys hidden in quantum mixed states. This would lead the way to extremely secure communication, likely applicable in 5 to 10 years.
China state-affiliated media
#Exclusive: Chinese scientists achieve #quantum information masking in lab, enabling non-copyable keys hidden in quantum mixed states. This would lead the way to extremely secure communication, likely applicable in 5 to 10 years.
globaltimes.cn
4:27 PM · May 6, 2021
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Researchers Construct Multiplexed Quantum Repeater Based on Absorptive Quantum Memories
Editor: LIU Jia | Jun 03, 2021
Chinese researchers realized an elementary link of a quantum repeater based on absorptive quantum memories (QMs) and demonstrated the multiplexed quantum repeater for the first time. The study was published in Nature.
The fundamental task of a quantum network is to distribute quantum entanglement between two remote locations. However, the transmission loss of optical fiber has limited the distance of entanglement distribution to approximately 100 km on the ground. Quantum repeaters can overcome this difficulty by dividing long-distance transmission into several short-distance elementary links. The entanglement of two end nodes of each link is created firstly. Then the entanglement distance is gradually expanded through entanglement swapping between each link.
--> Researchers Construct Multiplexed Quantum Repeater Based on Absorptive Quantum Memories----Chinese Academy of Sciences
www.nature.com
Editor: LIU Jia | Jun 03, 2021
Chinese researchers realized an elementary link of a quantum repeater based on absorptive quantum memories (QMs) and demonstrated the multiplexed quantum repeater for the first time. The study was published in Nature.
The fundamental task of a quantum network is to distribute quantum entanglement between two remote locations. However, the transmission loss of optical fiber has limited the distance of entanglement distribution to approximately 100 km on the ground. Quantum repeaters can overcome this difficulty by dividing long-distance transmission into several short-distance elementary links. The entanglement of two end nodes of each link is created firstly. Then the entanglement distance is gradually expanded through entanglement swapping between each link.
--> Researchers Construct Multiplexed Quantum Repeater Based on Absorptive Quantum Memories----Chinese Academy of Sciences
Heralded entanglement distribution between two absorptive quantum memories - Nature
Heralded entanglement is realized between two solid-state absorptive quantum memories 3.5 metres apart and with a bandwidth of 1 gigahertz, and with a fidelity of approximately 80%.
www.nature.com
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Demonstrating Quantum Communication Under Realistic Conditions
Researchers achieve secure “real-world” quantum communication along 428 km of optical fiber, the longest terrestrial distance outside of a lab setting.
Field Test of Twin-Field Quantum Key Distribution through Sending-or-Not-Sending over 428 km
Researchers achieve secure ``real-world'' quantum communication along 428 km of optical fiber, the longest terrestrial distance outside of a lab setting.
