Quantum Experiments at Space Scale (QUESS; ), is a Chinese research project in the field of quantum physics.
Tiangong-2
Tiangong-2 () was a Chinese space laboratory and part of the Project 921-2 space station program. Tiangong-2 was launched on 15 September 2016. It was deorbited as planned on 19 July 2019.
Tiangong-2 was neither designed nor planned to be a p ...
is China's second Space Laboratory module which was launched on 15 September 2016.
Tiangong-2
Tiangong-2 () was a Chinese space laboratory and part of the Project 921-2 space station program. Tiangong-2 was launched on 15 September 2016. It was deorbited as planned on 19 July 2019.
Tiangong-2 was neither designed nor planned to be a p ...
carries a total of 14 mission
and experiment packages, including Space-Earth
quantum key distribution
Quantum key distribution (QKD) is a secure communication method which implements a cryptographic protocol involving components of quantum mechanics. It enables two parties to produce a shared random secret key known only to them, which can then be ...
() and laser communications experiment to facilitate space-to-ground quantum communication.
A satellite, nicknamed Micius or
Mozi
Mozi (; ; Latinized as Micius ; – ), original name Mo Di (), was a Chinese philosopher who founded the school of Mohism during the Hundred Schools of Thought period (the early portion of the Warring States period, –221 BCE). The ancie ...
() after the ancient Chinese philosopher, is operated by the
Chinese Academy of Sciences
The Chinese Academy of Sciences (CAS); ), known by Academia Sinica in English until the 1980s, is the national academy of the People's Republic of China for natural sciences. It has historical origins in the Academia Sinica during the Republ ...
, as well as ground stations in China. The
University of Vienna
The University of Vienna (german: Universität Wien) is a public research university located in Vienna, Austria. It was founded by Duke Rudolph IV in 1365 and is the oldest university in the German-speaking world. With its long and rich histor ...
and the
Austrian Academy of Sciences are running the satellite's European receiving stations.
QUESS is a proof-of-concept mission designed to facilitate
quantum optics
Quantum optics is a branch of atomic, molecular, and optical physics dealing with how individual quanta of light, known as photons, interact with atoms and molecules. It includes the study of the particle-like properties of photons. Photons have b ...
experiments over long distances to allow the development of
quantum encryption
Quantum key distribution (QKD) is a secure communication method which implements a cryptographic protocol involving components of quantum mechanics. It enables two parties to produce a shared random secret key known only to them, which can then b ...
and
quantum teleportation technology.
Quantum encryption uses the principle of
entanglement to facilitate communication that can absolutely detect whether a third party has intercepted a message in transit thus denying undetected
decryption
In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Ideally, only authorized parties can decip ...
. By producing pairs of entangled
photons
A photon () is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless, so they alway ...
, QUESS will allow ground stations separated by many thousands of kilometres to establish secure
quantum channel
In quantum information theory, a quantum channel is a communication channel which can transmit quantum information, as well as classical information. An example of quantum information is the state of a qubit. An example of classical information i ...
s.
QUESS itself has limited communication capabilities: it needs
line-of-sight, and can only operate when not in sunlight.
Further Micius satellites were planned, including a global network by 2030.
The mission cost was around US$100 million in total.
Mission
The initial experiment demonstrated
quantum key distribution
Quantum key distribution (QKD) is a secure communication method which implements a cryptographic protocol involving components of quantum mechanics. It enables two parties to produce a shared random secret key known only to them, which can then be ...
(QKD) between
Xinjiang Astronomical Observatory
Xinjiang Astronomical Observatory (XAO; ) of the Chinese Academy of Sciences was known as Ürümqi Astronomical Observatory before it was renamed in January 2011.
The current research at XAO spans many fields of astronomy. It consists of radio ...
near
Ürümqi
Ürümqi ( ; also spelled Ürümchi or without umlauts), formerly known as Dihua (also spelled Tihwa), is the capital of the Xinjiang Uyghur Autonomous Region in the far northwest of the People's Republic of China. Ürümqi developed its ...
and
Xinglong Observatory near
Beijing
}
Beijing ( ; ; ), alternatively romanized as Peking ( ), is the capital of the People's Republic of China. It is the center of power and development of the country. Beijing is the world's most populous national capital city, with over 21 ...
– a
great-circle distance
The great-circle distance, orthodromic distance, or spherical distance is the distance along a great circle.
It is the shortest distance between two points on the surface of a sphere, measured along the surface of the sphere (as opposed to a ...
of approximately .
In addition, QUESS tested
Bell's inequality at a distance of – further than any experiment to date – and teleported a photon state between
Shiquanhe Observatory in
Ali
ʿAlī ibn Abī Ṭālib ( ar, عَلِيّ بْن أَبِي طَالِب; 600 – 661 CE) was the last of four Rightly Guided Caliphs to rule Islam (r. 656 – 661) immediately after the death of Muhammad, and he was the first Shia Imam. ...
,
Tibet Autonomous Region
The Tibet Autonomous Region or Xizang Autonomous Region, often shortened to Tibet or Xizang, is a Provinces of China, province-level Autonomous regions of China, autonomous region of the China, People's Republic of China in Southwest China. I ...
, and the satellite.
This requires very accurate
orbital maneuver
In spaceflight, an orbital maneuver (otherwise known as a burn) is the use of propulsion systems to change the orbit of a spacecraft.
For spacecraft far from Earth (for example those in orbits around the Sun) an orbital maneuver is called a ' ...
ing and satellite tracking so the base stations can keep line-of-sight with the craft.
In 2021 full quantum state teleportation was demonstrated over at ground, based on entanglement distributed by the satellite.
Once experiments within China concluded, QUESS created an international QKD channel between China and the
Institute for Quantum Optics and Quantum Information, Vienna, Austria − a ground distance of , enabling the first intercontinental secure quantum video call in 2016.
Launch
The launch was initially scheduled for July 2016, but was rescheduled to August, with notification of the launch being sent just a few days in advance.
The spacecraft was launched by a
Long March 2D
The Long March 2D (), also known as the Chang Zheng 2D, CZ-2D and LM-2D, is a Chinese two-stage orbital carrier rocket mainly used for launching LEO and SSO satellites. It is manufactured by the Shanghai Academy of Spaceflight Technology ( ...
rocket from
Jiuquan
Jiuquan, formerly known as Suzhou, is a prefecture-level city in the northwesternmost part of Gansu Province in the People's Republic of China. It is more than wide from east to west, occupying , although its built-up area is mostly located in ...
Launch Pad 603,
Launch Area 4 on 17 August 2016, at 17:40 UTC (01:40 local time).
Multi-payload mission
The launch was a multi-payload mission shared with QUESS, LiXing-1 research satellite, and ³Cat-2 Spanish science satellite.
* LiXing-1: LiXing-1 is a Chinese satellite designed to measure upper atmospheric density by lowering its orbit to 100–150 km. Its mass is 110 kg. On 19 August 2016, the satellite reentered into the atmosphere, so the mission is closed.
* ³Cat-2: The 3Cat-2 (spelled "cube-cat-two") is the second satellite in the 3Cat series and the second satellite developed in Catalonia at
Polytechnic University of Catalonia
The Technical University of Catalonia ( ca, Universitat Politècnica de Catalunya, , es, link=no, Universidad Politécnica de Cataluña; UPC), currently referred to as BarcelonaTech, is the largest engineering university in Catalonia, Spai ...
’s NanoSat Lab. It is a 6-Unit
CubeSat
A CubeSat is a class of miniaturized satellite based around a form factor consisting of cubes. CubeSats have a mass of no more than per unit, and often use commercial off-the-shelf (COTS) components for their electronics and structure. CubeSats ...
flying a novel
GNSS
A satellite navigation or satnav system is a system that uses satellites to provide autonomous geo-spatial positioning. It allows satellite navigation devices to determine their location (longitude, latitude, and altitude/elevation) to high pre ...
Reflectometer (GNSS-R) payload for Earth observation. Its mass is 7.1 kg.
Secure key distribution
The main instrument on board QUESS is a "
Sagnac effect
The Sagnac effect, also called Sagnac interference, named after French physicist Georges Sagnac, is a phenomenon encountered in interferometry that is elicited by rotation. The Sagnac effect manifests itself in a setup called a ring interferometer ...
"
interferometer
Interferometry is a technique which uses the ''interference'' of superimposed waves to extract information. Interferometry typically uses electromagnetic waves and is an important investigative technique in the fields of astronomy, fiber op ...
.
This is a device which generates pairs of entangled photons, allowing one of each to be transmitted to the ground. This will allow QUESS to perform
Quantum key distribution
Quantum key distribution (QKD) is a secure communication method which implements a cryptographic protocol involving components of quantum mechanics. It enables two parties to produce a shared random secret key known only to them, which can then be ...
(QKD) – the transmission of a secure
cryptographic key
A key in cryptography is a piece of information, usually a string of numbers or letters that are stored in a file, which, when processed through a cryptographic algorithm, can encode or decode cryptographic data. Based on the used method, the key c ...
that can be used to encrypt and decrypt messages – to two ground stations. QKD theoretically offers truly secure communication. In QKD, two parties who want to communicate share a random secret key transmitted using pairs of entangled photons sent with random
polarization, with each party receiving one half of the pair. This secret key can then be used as a
one-time pad
In cryptography, the one-time pad (OTP) is an encryption technique that cannot be cracked, but requires the use of a single-use pre-shared key that is not smaller than the message being sent. In this technique, a plaintext is paired with a ran ...
, allowing the two parties to communicate securely through normal channels. Any attempt to eavesdrop on the key will disturb the entangled state in a detectable way.
QKD has been attempted on Earth, both with direct line-of-sight between two observatories, and using
fibre optic
An optical fiber, or optical fibre in Commonwealth English, is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a means to ...
cables to transmit the photons. However, fibre optics and the atmosphere both cause scattering which destroys the entangled state, and this limits the distance over which QKD can be carried out. Sending the keys from an orbiting satellite results in less scattering, which allows QKD to be performed over much greater distances.
In addition, QUESS tests some of the basic foundations of
quantum mechanics
Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, ...
.
Bell's theorem says that no
local hidden-variable theory
In the interpretation of quantum mechanics, a local hidden-variable theory is a hidden-variable theory that satisfies the condition of being consistent with local realism. This includes all types of the theory that attempt to account for the proba ...
can ever reproduce the predictions of quantum physics, and QUESS will be able to test the
principle of locality
In physics, the principle of locality states that an object is influenced directly only by its immediate surroundings. A theory that includes the principle of locality is said to be a "local theory". This is an alternative to the concept of ins ...
over .
Analysis
QUESS lead scientist
Pan Jianwei told ''
Reuters
Reuters ( ) is a news agency owned by Thomson Reuters Corporation. It employs around 2,500 journalists and 600 photojournalists in about 200 locations worldwide. Reuters is one of the largest news agencies in the world.
The agency was estab ...
'' that the project has "enormous prospects" in the defence sphere.
The satellite will provide secure communications between Beijing and Ürümqi, capital of
Xinjiang
Xinjiang, SASM/GNC: ''Xinjang''; zh, c=, p=Xīnjiāng; formerly romanized as Sinkiang (, ), officially the Xinjiang Uygur Autonomous Region (XUAR), is an autonomous region of the People's Republic of China (PRC), located in the northwest ...
, the remote western region of China.
The
US Department of Defense
The United States Department of Defense (DoD, USDOD or DOD) is an executive branch department of the federal government charged with coordinating and supervising all agencies and functions of the government directly related to national secu ...
believes China is aiming to achieve the capability to counter the use of enemy space technology.
Chinese Communist Party
The Chinese Communist Party (CCP), officially the Communist Party of China (CPC), is the founding and One-party state, sole ruling party of the China, People's Republic of China (PRC). Under the leadership of Mao Zedong, the CCP emerged victoriou ...
general secretary
Secretary is a title often used in organizations to indicate a person having a certain amount of authority, power, or importance in the organization. Secretaries announce important events and communicate to the organization. The term is derived ...
Xi Jinping
Xi Jinping ( ; ; ; born 15 June 1953) is a Chinese politician who has served as the general secretary of the Chinese Communist Party (CCP) and chairman of the Central Military Commission (CMC), and thus as the paramount leader of China, s ...
has prioritised China's space program, which has included
anti-satellite missile
Anti-satellite weapons (ASAT) are space weapons designed to incapacitate or destroy satellites for strategic or tactical
purposes. Several nations possess operational ASAT systems. Although no ASAT system has been utilised in warfare, a few ...
tests, and the ''
New York Times
''The New York Times'' (''the Times'', ''NYT'', or the Gray Lady) is a daily newspaper based in New York City with a worldwide readership reported in 2020 to comprise a declining 840,000 paid print subscribers, and a growing 6 million paid d ...
'' noted that quantum technology was a focus of the
thirteenth five-year plan, which the China government set out earlier that year.
The ''Wall Street Journal'' said that the launch put China ahead of rivals, and brought them closer to "hack-proof communications".
Several outlets identified
Edward Snowden
Edward Joseph Snowden (born June 21, 1983) is an American and naturalized Russian former computer intelligence consultant who leaked highly classified information from the National Security Agency (NSA) in 2013, when he was an employee and su ...
's
leak of US surveillance documents as an impetus for the development of QUESS, with ''
Popular Science
''Popular Science'' (also known as ''PopSci'') is an American digital magazine carrying popular science content, which refers to articles for the general reader on science and technology subjects. ''Popular Science'' has won over 58 awards, incl ...
'' calling it "a satellite for the post-Snowden age".
Similar projects
QUESS is the first spacecraft launched capable of generating entangled photons in space,
although transmission of single photons via satellites has previously been demonstrated by reflecting photons generated at ground-based stations off orbiting satellites.
While not generating fully entangled photons,
correlated
In statistics, correlation or dependence is any statistical relationship, whether causal or not, between two random variables or bivariate data. Although in the broadest sense, "correlation" may indicate any type of association, in statistics ...
pairs of photons have been produced in space using a
cubesat
A CubeSat is a class of miniaturized satellite based around a form factor consisting of cubes. CubeSats have a mass of no more than per unit, and often use commercial off-the-shelf (COTS) components for their electronics and structure. CubeSats ...
by the
National University of Singapore
The National University of Singapore (NUS) is a national public research university in Singapore. Founded in 1905 as the Straits Settlements and Federated Malay States Government Medical School, NUS is the oldest autonomous university in the c ...
and the
University of Strathclyde
The University of Strathclyde ( gd, Oilthigh Shrath Chluaidh) is a public research university located in Glasgow, Scotland. Founded in 1796 as the Andersonian Institute, it is Glasgow's second-oldest university, having received its royal chart ...
.
A German consortium has performed quantum measurements of optical signals from the
geostationary
A geostationary orbit, also referred to as a geosynchronous equatorial orbit''Geostationary orbit'' and ''Geosynchronous (equatorial) orbit'' are used somewhat interchangeably in sources. (GEO), is a circular geosynchronous orbit in altitude ...
Alphasat
Inmarsat-4A F4, also known as Alphasat and Inmarsat-XL, is a large geostationary communications I-4 satellite operated by United Kingdom-based Inmarsat in partnership with the European Space Agency. Launched in 2013, it is used to provide mobile ...
Laser Communication Terminal. The US Defense Advanced Research Projects Agency (DARPA) launched the Quiness macroscopic quantum communications project to catalyze the development of an end-to-end global quantum internet in 2012.
In 2024,
ESA
, owners =
, headquarters = Paris, Île-de-France, France
, coordinates =
, spaceport = Guiana Space Centre
, seal = File:ESA emblem seal.png
, seal_size = 130px
, image = Views in the Main Control Room (1205 ...
intends to launch the Eagle-1 quantum key distribution satellite, with a goal similar to that of the Chinese QUESS. It will be part of the development and deployment of the European Quantum Communication Infrastructure (EuroQCI).
See also
*
Chinese space program
The space program of the People's Republic of China is directed by the China National Space Administration (CNSA). China's space program has overseen the development and launch of ballistic missiles, thousands of artificial satellites, mann ...
*
Quantum information
Quantum information is the information of the state of a quantum system. It is the basic entity of study in quantum information theory, and can be manipulated using quantum information processing techniques. Quantum information refers to both th ...
**
Quantum cryptography
Quantum cryptography is the science of exploiting quantum mechanical properties to perform cryptographic tasks. The best known example of quantum cryptography is quantum key distribution which offers an information-theoretically secure solution ...
**
Quantum computing
Quantum computing is a type of computation whose operations can harness the phenomena of quantum mechanics, such as superposition, interference, and entanglement. Devices that perform quantum computations are known as quantum computers. Though ...
**
Quantum key distribution
Quantum key distribution (QKD) is a secure communication method which implements a cryptographic protocol involving components of quantum mechanics. It enables two parties to produce a shared random secret key known only to them, which can then be ...
**
Quantum teleportation
References
External links
QUESS LaunchingChinese)
3Cat-2 Satellite web siteat
Polytechnic University of Catalonia
The Technical University of Catalonia ( ca, Universitat Politècnica de Catalunya, , es, link=no, Universidad Politécnica de Cataluña; UPC), currently referred to as BarcelonaTech, is the largest engineering university in Catalonia, Spai ...
{{Orbital launches in 2016
Communications satellites
Satellites of China
Satellites of Austria
2016 in China
Quantum information science
Spacecraft launched in 2016
Communications satellites in low Earth orbit
2016 in Austria