Quantum Supremacy: The infancy of the second quantum revolution is upon us
Michael Spencer
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Chinese Physicists display Multiphoton Entanglement with a Rydberg Superatom?
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In quantum computing, quantum supremacy or quantum advantage is the goal of demonstrating that a programmable quantum device can solve a problem that no classical computer can solve in any feasible amount of time.
Today we focus on a story out of China.
Is China Ahead in Entangled Photons?
China's quantum communication advantage could compound to other areas.
MONDAY AUGUST 15TH, 2022 11:50 AM MONTREAL, CANADA
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Hey Guys,
I recently came across a?paper ?and a?story? that caught my interest. I cover ChinaTech in its own Newsletter here.
According to this SCMP article, this has to do with quantum communications, something I have suspected China is in the global lead.
Ling Xing ?made a?good summary .
Sequential generation of multiphoton entanglement with a Rydberg superatom
A team of Chinese scientists report on a?new method for entangling photons?that they say could make quantum networks and quantum computing more practical, according to the South China Post.
Multiqubit entanglement is an indispensable resource for quantum information science. In particular, the entanglement of photons is of conceptual interest due to its implications in measurement-based quantum computing, communication and metrology.
The method has the potential to conserve laboratory resources and?accelerate research into quantum relay, a key technology for long-distance, attack-proof quantum communication, according to researchers from the?University of Science and Technology of China ?in the southeastern province of Anhui.
Towards Larger Scale Photonic Entanglement
They experimentally demonstrate an efficient approach for multiphoton generation with a Rydberg superatom, a mesoscopic atomic ensemble under Rydberg blockade.
Using it as an efficient single-photon interface, they iterate the photon creation process that gives rise to a train of single photons entangled in the time-bin degree of freedom. Photon correlations verify entanglement up to six qubits.
The Chinese physicists used a non-traditional method based on particle interaction to achieve entanglement, according to a paper published in the peer-reviewed?Nature Photonics?on Thursday, August 11th, 2022. Here we mean:
China has some of the world’s leading physicists working on things like this. There are a lot more just as their are in A.I. in American universities who will eventually go back to China. If Quantum computing has a talent shortage, that shortage won’t be in China.
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Rydberg “Superatom”
The team first captured hundreds of rubidium atoms to form a cluster known as a “superatom”. Then they stimulated one of the atoms to reach electronically excited states known as Rydberg states, named after the 19th century Swedish physicist Johannes Rydberg.
As the atom absorbed energy and grew bigger, it started to interact with nearby atoms, shift their energy levels and eventually become entangled with them.
Through this process, the rubidium atoms released a string of photons. The researchers confirmed the entanglement of up to six photons through the experiment.
Clearly China could play a major role in the future of quantum computing. China’s bleeding edge work in quantum communications is pushing the entire world faster. The same is beginning to happen in A.I. research papers.
So why is it more efficient? The Chinese scientists generated entangled photons at an efficiency rate of 27 per cent – a significant increase from the previous record of 16 per cent.
You can read a paper on a similar?topic here .
Controlling Single Photons with Rydberg Superatoms
Superatom Method is the Key
So here’s the part I found striking in particular.
Unlike spontaneous down-conversion, entangled photons generated with the Rydberg superatom method could theoretically achieve efficiency of 100 per cent under ideal conditions, the paper said.
While each crystal in the spontaneous down-conversion method produces just one entangled pair of photons, scientists could use the superatom method to produce as many entangled photons as possible.
The research was funded by the Ministry of Science and Technology, the National Natural Science Foundation of China, the Anhui provincial government, and the Hefei National Laboratory for Physical Sciences at the Microscale.
What do you make of this?
These schemes are, in principle, deterministic and can scale up to a vast number of photons. Moreover, they have an additional advantage of being resource efficient since merely one setup is required. Albeit very promising in theory, it is technically demanding in experiments.
Think about it, the old way of doing things might become a thing of the past now. The most popular way to create?entangled photons?in a laboratory is to shine a strong laser beam into a special crystal.
While most photons continue straight through the crystal, a few of the particles of light undergo a process called spontaneous parametric down-conversion and split into a pair of lower energy photons that are entangled with each other. According to the SCMP’s coverage, this method is inefficient and unpredictable, with only about one entangled pair generated from tens of millions of photons.
If China’s R&D and papers in Quantum communications and separately in A.I. are getting better, clearly they will be leaders in AQ, the harnessing of machine learning and quantum computing together for science, technology and innovation.
Of course in the West, all the hype is based on startups, BigTech and initiatives by DARPA, IBM and the like. There’s clearly a lot of science going on in China that we may not even be fully aware of.
Entangled photons are needed for certain forms of quantum communication and computing. I personally think this research and its implications goes beyond just quantum relays.
Towards an AQ Future
The?Quantum Insider? also covered the story, the summarized it as the team said that their approach centered on multiphoton generation with a Rydberg superatom, which is an atomic ensemble. They used it as an efficient single-photon interface, creating a train of photons.
The scaling of the photons is what’s truly the most impressive thing here. We are clearly going to witness a lot of important research in the 2020s regarding the future of quantum computing, quantum communications and quantum machine learning as the science of AQ truly comes together.
Thanks for reading!
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I've started a Newsletter for quantum computing news, if this field interests you, you can subscribe?here . I cannot continue to write without tips, sponsorship and community support. (follow the link below).
https://ipotimes.substack.com/subscribe
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2 年Thank you Michael Spencer for putting in the work!!
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2 年Thanks for posting