News on China's scientific and technological development.

gelgoog

Brigadier
Registered Member
Contrary to what most people think Tokamak technology can already achieve net energy output slightly above break even.

The first Tokamak to do it was the Japanese JT-60U. It achieved with D-D fusion an energy result that with D-T fuel would have been above breakeven. The reactor itself doesn't support Tritium injection and most reactors which use Tritium have shortened lifespans because of the neutron flow. The net ratio was 1.25 i.e. 25% energy gain. Which is pitifully low but still. Existing reactors with D-T all have lifetime issues and all are still low density. Just look at the size of ITER and compare that with a regular fission power plant.
 

Temstar

Brigadier
Registered Member
The lead scientist proposed going this path in 2009. 11 years work now paid out now.
View attachment 66185

Here is report from his team
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I've been reading up on this. It seems the trick to this engine is that bend in the middle of the engine. The geometry means the hot fuel/air mix end up detonating instead of deflagrate at the bend. The detonation has twice the thermal efficiency and density as deflagration so for a given engine size a much more powerful reaction could be maintained, thus greatly increasing the engine's thrust. This engine also has no moving parts.
 

AndrewS

Brigadier
Registered Member
Chinese researchers claim to have achieved quantum supremacy
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Quantum computer is capable of performing calculations trillions of times faster than rivals, say scientists

Researchers in China have claimed to have achieved quantum supremacy, building a quantum computer capable of carrying out calculations trillions of times faster than today’s most powerful supercomputers.

According to a paper published in the journal Science on Thursday, the computer, developed by a team of scientists at the University of Science and Technology of China in central Hefei, completed a calculation almost 100tn times quicker than existing supercomputers.

The breakthrough comes a year after Google proclaimed itself the first to reach the milestone with its Sycamore machine.

According to Lu Chaoyang, a professor in charge of the experiment at USTC, the Chinese computer achieved the breakthrough by manipulating particles of light. This contrasts with Google’s supercomputer, which relied on ultra-cold superconducting chips.

Christine Silberhorn, an expert in quantum optics at Paderborn University in Germany, called the Chinese team’s work a “milestone experiment”.

While the use of quantum machines to solve practical problems is still years away, the emerging field is hotly contested, with the US and China racing to gain advantages in areas such as encryption and complex problem-solving.

In 2017 Ms Silberhorn was one of the co-developers of the technique known as “Gaussian boson sampling”, which the Chinese team built on with their machine. “The concepts used were in the literature, but this experiment demonstrates the scaling, which is a crucial step,” she said.

China’s official news agency Xinhua claimed the computer, which comprises lasers, mirrors, prisms and photon detectors, could process 10bn times faster than the quantum computer unveiled by Google last year. Google did not immediately respond to a request for comment.

Mr Lu said he admired Google’s work. “Building a quantum computer is a race between humans and nature, not between countries,” he said, adding that so far the “quantum machine can only do a specific job, not all jobs. It is not fully programmable yet. This is something we are working on.”

If they can be built at scale, quantum computers will harness properties that extend beyond the limits of classical physics to offer exponential gains in computing power.

“Scientists are close to useful quantum machines that can do something non-trivial,” Mr Lu added.

Richard Murray, chief executive of London-based quantum computing company ORCA, said the news was encouraging for the whole industry.

“There are still people who question whether quantum computers will be a reality,” he said. “With two systems having achieved this benchmark, that argument is sounding quite unlikely.”

Additional reporting by Nian Liu in Beijing
 

Hendrik_2000

Lieutenant General
The Jiuzhang quantum computer has achieved quantum supremacy (quantum advantage), according to the study “Quantum computational advantage using photons”, published in Science on 3 December 2020. Pan Jian-Wei, professor, University of Science and Technology of China, explains how the Jiuzhang quantum computer was used. Credit: Quantum computational advantage using photons Han-Sen Zhong, Hui Wang, Yu-Hao Deng, Ming-Cheng Chen, Li-Chao Peng, Yi-Han Luo, Jian Qin, Dian Wu, Xing Ding, Yi Hu, Peng Hu, Xiao-Yan Yang, Wei-Jun Zhang, Hao Li, Yuxuan Li, Xiao Jiang, Lin Gan, Guangwen Yang, Lixing You, Zhen Wang, Li Li, Nai-Le Liu, Chao-Yang Lu, Jian-Wei Pan
 

localizer

Colonel
Registered Member
The Jiuzhang quantum computer has achieved quantum supremacy (quantum advantage), according to the study “Quantum computational advantage using photons”, published in Science on 3 December 2020. Pan Jian-Wei, professor, University of Science and Technology of China, explains how the Jiuzhang quantum computer was used. Credit: Quantum computational advantage using photons Han-Sen Zhong, Hui Wang, Yu-Hao Deng, Ming-Cheng Chen, Li-Chao Peng, Yi-Han Luo, Jian Qin, Dian Wu, Xing Ding, Yi Hu, Peng Hu, Xiao-Yan Yang, Wei-Jun Zhang, Hao Li, Yuxuan Li, Xiao Jiang, Lin Gan, Guangwen Yang, Lixing You, Zhen Wang, Li Li, Nai-Le Liu, Chao-Yang Lu, Jian-Wei Pan

Sucks they still buy everything from Thorlabs
1607101539733.png
 

localizer

Colonel
Registered Member
Firstly, Thorlabs may be the best choice in terms of specification.
Secondly, even if there are alternatives from other country, you would not through away your pricey "Thorlabs" that you already bought just because it is made in US.
But it shows how China still lacks in precision machining and optical materials. It'll be very hard to get to fully domestic DUV/EUV without significant improvements in optomechanics manufacturing.

I've bought some Chinese lenses and mounts before, only thing going for them is price. Probably best for use in education.
 
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