physics

Quantum Experiments at Space Scale

Quantum Experiments at Space Scale is a physics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Quantum Experiments at Space Scale rather than just read about it. In short: Quantum Experiments at Space Scale (QUESS; Chinese: 量子科学实验卫星; pinyin: Liàngzǐ kēxué shíyàn wèixīng; lit. 'Quantum Science Experiment Satellite'), is a Chinese research project in the field of quantum physics. QUESS was launched on 15 August 2016.

Key takeaways

Quantum Experiments at Space Scale belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Quantum Experiments at Space Scale to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Quantum Experiments at Space Scale from memory before moving on to harder problems.

Reference excerpt

Quantum Experiments at Space Scale (QUESS; Chinese: 量子科学实验卫星; pinyin: Liàngzǐ kēxué shíyàn wèixīng; lit. 'Quantum Science Experiment Satellite'), is a Chinese research project in the field of quantum physics. QUESS was launched on 15 August 2016. The project consists of the satellite Micius, or Mozi (Chinese: 墨子), after the ancient Chinese philosopher, operated by the Chinese Academy of Sciences, as well as ground stations in China. The University of Vienna and the Austrian Academy of Sciences are running the satellite's European receiving stations. The satellite conducted Space-Earth quantum key distribution (Chinese: 量子密钥分发) experiments, facilitated by laser communications experiment carried on Tiangong-2 space laboratory module.

Design and development QUESS is a proof-of-concept mission designed to facilitate quantum optics experiments over long distances to allow the development of quantum encryption and quantum teleportation technology. The project originated in the 1990s as first a competition and later a collaboration between Anton Zeilinger and his Ph.D. student Jianwei Pan, to send quantum information across every larger distances. The Chinese government quickly funded Pan's project to build a satellite; unable to get funding for a European satellite, Zeilinger became a collaborator with Micius. 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. By producing pairs of entangled photons, QUESS will allow ground stations separated by many thousands of kilometres to establish secure quantum channels. 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. In March 2025, researchers reported the development of the world’s first quantum microsatellite, Jinan-1, and demonstrated real-time satellite-based quantum key distribution (QKD) with multiple compact ground stations in China and South Africa. During experiments, Jinan-1 established optical links with ground stations in cities including Jinan, Hefei, Wuhan, Shanghai, and Stellenbosch and generated secure keys in real time, enabling encrypted communication between Beijing and Stellenbosch over a distance of approximately 12,900 km. The experiment showed the feasibility of using lightweight microsatellites and portable ground stations for long-distance quantum communication, laying groundwork for potential constellations of quantum satellites and large-scale quantum networks.

Mission

The initial experiment demonstrated quantum key distribution (QKD) between Xinjiang Astronomical Observatory near Ürümqi and Xinglong Observatory near Beijing – a great-circle distance of approximately 2,500 kilometres (1,600 mi). In addition, QUESS tested Bell's inequality at a distance of 1,200 km (750 mi) – further than any experiment to date – and teleported a photon state between Shiquanhe Observatory in Ali, Tibet Autonomous Region, and the satellite. This requires very accurate orbital maneuvering and satellite tracking so the base stations can keep line-of-sight with the craft. In 2021 full quantum state teleportation was demonstrated over 1,200 km (750 mi) 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 7,500 km (4,700 mi), 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 rocket from Jiuquan 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's NanoSat Lab. It is a 6-Unit CubeSat flying a novel GNSS Reflectometer (GNSS-R) payload for Earth observation. Its mass is 7.1 kg.

Secure key distribution

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Quantum Experiments at Space Scale

Start with the simplest possible case. Write down what Quantum Experiments at Space Scale claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Quantum Experiments at Space Scale before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Quantum Experiments at Space Scale ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Quantum Experiments at Space Scale

In research: Quantum Experiments at Space Scale appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Quantum Experiments at Space Scale in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Quantum Experiments at Space Scale is common in secondary-school and first-year university syllabi. It links to neighbouring topics 2016 in Austria, 2016 in China, Communications satellites, so understanding it makes those chapters shorter.
In everyday life: Look for Quantum Experiments at Space Scale outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Quantum Experiments at Space Scale in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Quantum Experiments at Space Scale means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Quantum Experiments at Space Scale out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Quantum Experiments at Space Scale in simple terms?

Why does Quantum Experiments at Space Scale matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Quantum Experiments at Space Scale?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Quantum Experiments at Space Scale.