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中國高科技篇：人造太陽與融合核能 -- Caroline Delbert
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2024/07/10 10:30 瀏覽209 ｜回應1｜推薦1 |
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請參見《中美競爭打造”人造太陽”爭奪世界霸權》。
China's Artificial Sun Generated a Magnetic Field, Clearing a Real Path for Fusion
It’s a crucial step forward in the quest for clean energy.
Caroline Delbert, 07/09/24
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* China’s large Huanliu-3 nuclear fusion reactor (「環流三號」核融合反應爐) follows decades of research in Chengdu.
* The world’s dozens of active tokamak experiments share ideas, scientists, and more.
* This tokamak, like many others, contributes to International Thermonuclear Experimental Reactor (ITER).
China joined the quest for an enormous, internationally cooperative nuclear fusion reactor in 2023. Now, they’ve reached a milestone by generating its magnetic field for the first time—a field that is entirely new in tis design. The “artificial sun” reactor, Huanliu-3 (HL-3), is a tokamak run by 17 collaborating labs and facilities around the world. But the much-ballyhooed quest to make energy using these huge reactors still has a decade or more to go, with a lot of misinformation in the mix.
While HL-3 puts China in the group of forerunners in nuclear fusion research, this reactor isn’t the largest (by far), and this milestone is only for its own timeline. This reactor is not close to operating consistently or producing energy that compares to the vast amounts of energy it and other similar reactors—known as tokamaks—require to operate. But HL-3, like many global tokamaks, is considered a proving ground for technologies that nations like China will offer to the truly world-leading ITER project in France. In that sense, each nation’s developments could make a difference going forward.
A tokamak is a donut-shaped (toroidal, in the science parlance) container that holds a stream of superheated magnetic plasma and is reinforced by massive magnets and supercooling encasement. The plasma—a cohesive “cloud” of atoms under star-like conditions—ends up hosting the same reactions that fuel the actual stars. The nuclei of atoms fuse together and release an enormous amount of energy... in theory. We know it happens in the stars, but we’ve never seen it happen inside a thousand-ton piece of machinery on Earth.
So, what does it mean for a world-class “artificial sun” tokamak reactor like HL-3 to establish its own, novel magnetic field design? Well, it’s a huge milestone within the field of tokamak research, as the magnetic field is what actually contains the superheated, fusion-generating plasma. Because plasma reaches a million degrees, it can’t make contact with any other material, or it will both instantly cool down out of the energy range and damage or destroy the part it touches. As such, a successful magnetic field is the only thing that will ever allow a tokamak to contain the plasma and keep it hot enough to make net energy.
There are a number of structural issues with how today’s tokamaks build their magnetic fields. The extremely huge electromagnets used in these machines are key to tokamaks’ designs (ITER received the most powerful magnet ever made in 2021), and they're under development all the time. But they all create hotspots that interrupt the plasma like an island in a stream—either because they are discretely installed at intervals around the shell of the tokamak, or simply because they’re made (by humans) of the naturally occurring materials we have on Earth.
In the cosmos, stars are not contained, so this never comes up. But in a generator, it's yet another hurdle to overcome.
All this means that a new configuration for a magnetic field can be a huge step forward, especially for HL-3, which is considered a feeder technology for ITER. Chinese media reports that China has signed on to build a vacuum chamber module for ITER. The vacuum vessel is essential to ITER’s goals, because it helps make the experiment plausibly safe to do—to contain a starlike reaction along the French waterfront.
it difficult to scrutinize Chinese projects like HL-3, and there aren’t a lot of meaningful comparisons between the world’s dozens of active projects in existence. China has another active nuclear fusion reactor in the international eye (Experimental Advanced Superconducting Tokamak, or EAST), which has been iterated upon China’s Hefei Institutes of Physical Science since the 2000s.
HL-3, however, comes from a lineage at Southwestern Institute of Physics in Chengdu, 900 miles west on the cusp of vast Western China. That program dates back decades as well, and both have steadily grown more and more powerful over decades of huge upgrades and rebuilds. HL-3 improves on previous designs, and is likely to get a larger machine with a larger overall amount of power going.
We still have never reached the threshold where a nuclear fusion reactor makes more energy than it uses, and to be honest, it’s not clear that we definitely will. But each step forward in proven tokamak technology brings the possibility of nuclear fusion energy closer to reality. And when we’re so many steps away, every little bit counts.
CAROLINE DELBERT is a writer, avid reader, and contributing editor at Pop Mech. She's also an enthusiast of just about everything. Her favorite topics include nuclear energy, cosmology, math of everyday things, and the philosophy of it all.
本文於 2025/03/17 14:31 修改第 2 次
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中國量子計算取得突破性進展 - Alan Bradley
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2025/03/17 14:27 推薦1 |
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請參閱：《中國祖沖之3.0量子電腦突破性進展》一文。
China achieves quantum supremacy claim with new chip 1 quadrillion times faster than the most powerful supercomputers
Alan Bradley, 03/13/25
This new superconducting prototype quantum processor achieved benchmarking results to rival Google's new Willow QPU.
Researchers in China have developed a quantum processing unit (QPU) that is 1 quadrillion (10¹⁵) times faster than the best supercomputers on the planet.
The new prototype 105-qubit chip, dubbed "Zuchongzhi 3.0," which uses superconducting qubits, represents a significant step forward for quantum computing, scientists at the University of Science and Technology of China (USTC) in Hefei said.
It rivals the benchmarking results set by Google's latest Willow QPU in December 2024 that allowed scientists to stake a claim for quantum supremacy — where quantum computers are more capable than the fastest supercomputers — in lab-based benchmarking.
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The scientists used the processor to complete a task on the widely used quantum computing random circuit sampling (RSC) benchmark in just a few hundred seconds, they said in a new study published March 3 in the journal Physical Review Letters.
This test, 83-qubit, 32-layer random circuit sampling task, was also completed 1 million times faster than the result set by Google's previous generation Sycamore chip, published in October 2024. Frontier, the second-fastest supercomputer in the world, would only be able to complete the same task in 5.9 billion years, by contrast
Although the results suggest QPUs are capable of achieving quantum supremacy, the specific RCS benchmarking used favors quantum methods. Also, improvements in classical algorithms that drive classical computing may close the gap, as happened in 2019 when Google scientists first announced a quantum computer had outperformed a classical computer — in the first use of the RSC benchmark.
"Our work not only advances the frontiers of quantum computing, but also lays the groundwork for a new era where quantum processors play an essential role in tackling sophisticated real-world challenges," the scientists said in the study.
Rivaling Google's best quantum processor
The latest iteration of Zuchongzhi includes 105 transmon qubits — devices made from metals like tantalum, niobium, and aluminum that have reduced sensitivity to noise — in a 15-by-7 rectangular lattice. This builds on the previous chip, which included 66 qubits.
One of the most important areas critical to the viability of quantum computing in real-world settings is coherence time, a measure of how long a qubit can maintain its superposition and tap into the laws of quantum mechanics to perform calculations in parallel. Longer coherence times mean more complicated operations and calculations are possible.
Another major improvement was in gate fidelity and quantum error correction, which has been an obstacle to building useful quantum computers. Gate fidelity measures how accurately a quantum gate performs its intended operation, where a quantum gate is analogous to a classical logic gate, performing a specific operation on one or more qubits, manipulating their quantum state. Higher fidelity qubits mean fewer errors and more accurate computations.
Zuchongzhi 3.0 performed with an impressive parallel single-qubit gate fidelity of 99.90%, and a parallel two-qubit gate fidelity of 99.62%. Google's Willow QPU edged it slightly, with results of 99.97% and 99.86% respectively.
These improvements were largely possible due to engineering improvements, including enhancements in fabrication methods and better optimized qubits design, the scientists said in the study. For instance, the latest iteration lithographically defines qubit components using tantalum and aluminum, bonded through an indium bump flip-chip process. This improves accuracy and minimizes contamination.
Alan Bradley is a freelance tech and entertainment journalist who specializes in computers, laptops, and video games. He's previously written for sites like PC Gamer, GamesRadar, and Rolling Stone. If you need advice on tech, or help finding the best tech deals, Alan is your man.
Related:
World's 1st modular quantum computer that can operate at room temperature goes online
Quantum computers are here — but why do we need them and what will they be used for?
Breakthrough quantum chip that harnesses new state of matter could set us on the path to quantum supremacy
Scientists create world's 1st chip that can protect data in the age of quantum computing attacks
本文於 2025/03/17 14:29 修改第 1 次
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