News on China's scientific and technological development.

Quickie

Colonel
Here is the definition of microgravity.

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A condition in which an object in the gravitational field of some other body (such as the Earth) is accelerated freely as a result of the gravitational force. ... Since the normal experience of weight on Earth is the result of forces that resist gravity, objects in microgravity appear weightless.
 

SamuraiBlue

Captain
I've done scuba diving, and it's not an apples to apples comparison on the neutral buoyancy you speak of, because I didn't see anyone else in the dive group without their lead belts and scuba tanks.

Don't really understand what you are trying to rely.
Basically even in water with neutral buoyancy trying to make you float in water, all molecules within your body is still being pull down by gravitational force making you realize which way is down.
 

solarz

Brigadier
Don't really understand what you are trying to rely.
Basically even in water with neutral buoyancy trying to make you float in water, all molecules within your body is still being pull down by gravitational force making you realize which way is down.

Actually, one of the dangers of diving is getting disoriented and not knowing which way is up. This can be especially dangerous when it's dark.
 

SamuraiBlue

Captain
Actually, one of the dangers of diving is getting disoriented and not knowing which way is up. This can be especially dangerous when it's dark.
That is because they are tossed around in choppy waters which creates various G force regardless of Earth's natural G and the unfortunate soul will lose his/her senses whether the person is in water or not.
In relatively calm waters under neutral bouncy once you exhale and inhale air both will disrupt neutrality and will make you boob up and down showing which is up and down. Further more your body will feel earth's natural G force pulling you down regard less of bouncy.
 

dingyibvs

Junior Member
Water can be used to simulate zero-G environment because buyoancy can be managed to cancel out gravity, so while a person still experiences gravity, the net force is about zero. A womb, however, isn't big enough for the fetus to float, it only maintains a size barely enough to hold the fetus inside, which is why a woman's belly grows as the fetus grows in size.
 

N00813

Junior Member
Registered Member
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Chinese scientists make quantum leap in computing
Source: Xinhua| 2017-05-03 10:20:03|Editor: An

136253132_14937885141971n.jpg


Chinese leading quantum physicist Pan Jianwei (2nd R), an academician of the Chinese Academy of Sciences and his colleagues announce their achievements at a press conference in Shanghai, east China, May 3, 2017. Chinese scientists have built world's first quantum com
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g machine that goes beyond the early classical -- or conventional -- computers, paving the way to the ultimate realization of quantum computing beating classical computers. (Xinhua/Jin Liwang)

SHANGHAI, May 3 (Xinhua) -- Chinese scientists have built world's first quantum com
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g machine that goes beyond the early classical -- or conventional -- computers, paving the way to the ultimate realization of quantum computing beating classical computers.

Scientists announced their achievement at a press conference in the Shanghai Institute for Advanced Studies of University of Science and Technology of China on Wednesday.

Many scientists believe quantum computing could in some ways dwarf the processing power of today's supercomputers. The manipulation of multi-particle entanglement is the core of quantum computing technology and has been the focus of international competition in quantum computing research.

Recently, Chinese leading quantum physicist Pan Jianwei, an academician of the Chinese Academy of Sciences and his colleagues -- Lu Chaoyang and Zhu Xiaobo, of the University of Science and Technology of China, and Wang Haohua, of Zhejiang University -- set two international records in quantum control of the maximal numbers of entangled photonic quantum bits and entangled superconducting quantum bits.

Pan said quantum computers could, in principle, solve certain problems faster than classical computers. Despite substantial progress in the past two decades, building quantum machines that can actually outperform classical computers in some specific tasks -- an important milestone termed "quantum supremacy" -- remains challenging.

In the quest for quantum supremacy, Boson sampling, an intermediate (that is, non-universal) quantum computer model has received considerable attention, as it requires fewer physical resources than building universal optical quantum computers, Pan said.

Last year, Pan and Lu Chaoyang developed the world's best single photon source based on semiconductor quantum dots. Now, they are using the high-performance single photon source and electronically programmable photonic circuit to build a multi-photon quantum computing prototype to run the Boson sampling task.

The test results show the sampling rate of this prototype is at least 24,000 times faster than international counterparts, according to Pan's team.

At the same time, the prototype quantum computing machine is 10 to 100 times faster than the first electronic computer, ENIAC, and the first transistor computer, TRADIC, in running the classical algorithm, Pan said.

It is the first quantum computing machine based on single photons that goes beyond the early classical computer, and ultimately paves the way to a quantum computer that can beat classical computers. This achievement was published online in the latest issue of Nature Photonics this week.

136253132_14937885142821n.jpg


Chinese leading quantum physicist Pan Jianwei, an academician of the Chinese Academy of Sciences, announces the achievements at a press conference in Shanghai, east China, May 3, 2017. Chinese scientists have built world's first quantum computing machine that goes beyond the early classical -- or conventional -- computers, paving the way to the ultimate realization of quantum computing beating classical computers. (Xinhua/Jin Liwang)

The Nature paper:
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