I think people from within whatever industry，always have a clear head compare to general public whom only consumes sensational articles from the media
Quantum computing thread
- Thread starter tphuang
- Start date
I think people from within whatever industry，always have a clear head compare to general public whom only consumes sensational articles from the media
It is concerning that there such large gaps in quantum computing equipment. Better for it to happen so early in the race, I suppose, rather than later. At this junction there will likely be a smaller impact than if it happens later in the race. At the very least the sanctions will force Chinese companies to face geopolitical realities and become self reliant early on.
22 Feb 2023
Not exactly a breakthrough yet, they still tinkering with it.
The article says that logical qubit in the Google experiment was still not as reliable, even though this particular experiment should be viewed as a success.
Two questions come to mind.
1) The idea is those qubits are still unstable in that frozen contraption. Just my impression that the photonic quantum computer has more stable qubits.
2) So how did they really do the error correction, was it on a classical computer? Maybe that is why we hearing all this quantum computer to be working side by side with a classical computer in China of how they setting it up.
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Intel is trying to fast track commercialization like Origin Quantum. The problem: its quantum computer doesn't exist yet.
What kind of developer would put work into making software for an imaginary machine? Plus, there's no guarantee the end product will work the same way as in the simulation.
As I've explained before, modern chips at the nano level experience minor quantum effects. Exploiting this phenomenon (instead of superconducting or optical methods) with existing manufacturing tools seems to be
What kind of developer would put work into making software for an imaginary machine? Plus, there's no guarantee the end product will work the same way as in the simulation.
As I've explained before, modern chips at the nano level experience minor quantum effects. Exploiting this phenomenon (instead of superconducting or optical methods) with existing manufacturing tools seems to be
Paper:
News:
北京量子信息科学研究院光量子通信与器件团队成员周来表示，量子密钥分发基于量子的不可测量、不可克隆性，以及一次一密的加密方法，可实现无条件安全通信。
2018年英国东芝欧洲研究所提出新型双场协议，使得安全成码率以信道衰减的平方根线性下降，在无中继的情况下可突破码率界限，是实现500公里以上光纤量子通信的可行方案。双场协议的实现需要两个异地的独立激光源在第三方远程节点处实现稳定的单光子干涉，但通信双方激光源的微小频差与长距离光纤造成的快速相位漂移都对干涉有重要影响。
周来说，传统方案是在遥远两地间架设服务光纤作为传输媒介，然后通过时频传输或者光学锁相环等技术，完成两地激光源的频率锁定。
袁之良团队首次将光频梳技术应用于双场量子密钥分发，一束单频率的光通过电光调制器成为多频率的光，且频率像梳子上的梳齿一样间隔均匀。研制出首个开放式架构、无需服务光纤的新型双场量子密钥分发系统，实现了低损耗光纤四百公里级、五百公里级、六百公里级的安全成码，并且打破无中继量子密钥分发的码率界限，成功演示了臂长差为百公里的量子密钥分发实验，这也是目前最长臂长差记录。
周来说，相较之前的实验成果，量子信号光的相位漂移速率降低1000多倍，大大降低相位参考光的噪声影响，有助于光纤量子密钥分发距离向千公里级别突破。同时，基于光频梳的开放式架构有利于未来构建多用户多节点的城际量子保密网络，并对基于单光子干涉的分布式量子网络具有重要意义。(完)
Twin-field quantum key distribution without optical frequency dissemination
Abstract
Twin-field (TF) quantum key distribution (QKD) has rapidly risen as the most viable solution to long-distance secure fibre communication thanks to its fundamentally repeater-like rate-loss scaling. However, its implementation complexity, if not successfully addressed, could impede or even prevent its advance into real-world. To satisfy its requirement for twin-field coherence, all present setups adopted essentially a gigantic, resource-inefficient interferometer structure that lacks scalability that mature QKD systems provide with simplex quantum links. Here we introduce a technique that can stabilise an open channel without using a closed interferometer and has general applicability to phase-sensitive quantum communications. Using locally generated frequency combs to establish mutual coherence, we develop a simple and versatile TF-QKD setup that does not need service fibre and can operate over links of 100 km asymmetry. We confirm the setup’s repeater-like behaviour and obtain a finite-size rate of 0.32 bit/s at a distance of 615.6 km.News:
中国科学家首次实现615公里开放式架构双场量子密钥分发
北京3月9日电 (记者 陈杭)记者9日从北京量子信息科学研究院获悉，该院袁之良团队利用光频梳技术首次实现开放式架构双场量子密钥分发系统，完成615公里光纤量子密钥分发实验。相关研究成果近日发表在国际学术期刊《自然-通讯》(Nature Communications)上。北京量子信息科学研究院光量子通信与器件团队成员周来表示，量子密钥分发基于量子的不可测量、不可克隆性，以及一次一密的加密方法，可实现无条件安全通信。
2018年英国东芝欧洲研究所提出新型双场协议，使得安全成码率以信道衰减的平方根线性下降，在无中继的情况下可突破码率界限，是实现500公里以上光纤量子通信的可行方案。双场协议的实现需要两个异地的独立激光源在第三方远程节点处实现稳定的单光子干涉，但通信双方激光源的微小频差与长距离光纤造成的快速相位漂移都对干涉有重要影响。
周来说，传统方案是在遥远两地间架设服务光纤作为传输媒介，然后通过时频传输或者光学锁相环等技术，完成两地激光源的频率锁定。
袁之良团队首次将光频梳技术应用于双场量子密钥分发，一束单频率的光通过电光调制器成为多频率的光，且频率像梳子上的梳齿一样间隔均匀。研制出首个开放式架构、无需服务光纤的新型双场量子密钥分发系统，实现了低损耗光纤四百公里级、五百公里级、六百公里级的安全成码，并且打破无中继量子密钥分发的码率界限，成功演示了臂长差为百公里的量子密钥分发实验，这也是目前最长臂长差记录。
周来说，相较之前的实验成果，量子信号光的相位漂移速率降低1000多倍，大大降低相位参考光的噪声影响，有助于光纤量子密钥分发距离向千公里级别突破。同时，基于光频梳的开放式架构有利于未来构建多用户多节点的城际量子保密网络，并对基于单光子干涉的分布式量子网络具有重要意义。(完)
USTC increased the throughput of QKD by an order of magnitude.
News:
QKD基于量子力学基本原理，可以实现原理上无条件安全的保密通信，提高成码率对其实用化起着至关重要的作用。高码率可为更多用户提供服务，实现大数据共享、分布式存储加密等高带宽需求的应用。此前国际上最高的实时成码率是每秒10兆比特（10公里标准光纤信道下）。为了实现更高的密钥率，需要解决系统发送端、接收端和后处理等技术瓶颈。在发送端，高码率QKD需要高保真度的量子态调制，然而现有QKD系统在高速调制下会产生较高误码率；在接收端，同时具有高效率和高计数率能力的单光子探测器不可或缺，超导纳米线单光子探测器（SNSPD）具有高效率和低噪声的优点，但其计数率通常受到较长恢复时间的限制。
潘建伟、徐飞虎研究组发展了集成光子片上高速高保真度偏振态调制技术，系统重频达到2.5吉赫兹，量子比特误码率优于0.35%；结合中科院上海微系统所尤立星团队最新研制的八像素SNSPD，实现了高计数率、高效率的单光子探测，在每秒输入5.5亿个光子时仍能保持62%的探测效率；同时，研究组发展了偏振反馈控制、高速后处理模块等。
在上述技术突破的基础上，研究团队实现了10公里标准光纤信道下每秒115.8兆比特的密钥率，较之前纪录提高了约一个数量级；系统稳定运行超过50个小时，在传输距离328公里下码率超过每秒200比特。
研究成果表明，QKD可实现百兆比特率的实时密钥分发，满足高带宽通信需求，对未来量子通信的大规模实际应用具有重要意义。
High-rate quantum key distribution exceeding 110 Mb s–1
Abstract
Quantum key distribution (QKD) can provide fundamentally proven secure communication. Towards application, the secret key rate (SKR) is a key figure of merit for any QKD system. The SKR has so far been limited to about a few megabits per second. Here we report a QKD system that is able to generate keys at a record high SKR of 115.8 Mb s–1 over a 10 km standard optical fibre, and distribute keys over up to 328 km of ultralow-loss fibre. Such abilities are attributed to a multipixel superconducting nanowire single-photon detector with an ultrahigh counting rate, an integrated transmitter that can stably encode polarization states with low error, a fast post-processing algorithm for generating keys in real time and the high system clock rate operation. The results demonstrate the feasibility of practical high-rate QKD with photonic techniques, thus opening its possibility for widespread applications.News:
我国实现百兆比特率量子密钥分发
科技日报合肥3月14日电 （记者吴长锋）记者14日从中国科学技术大学获悉，该校潘建伟院士、徐飞虎教授等与中科院上海微系统与信息技术研究所等单位的科研人员合作，通过发展高保真度集成光子学量子态调控、高计数率超导单光子探测等关键技术，首次在国际上实现百兆比特率的实时量子密钥分发（QKD），实验结果将此前的成码率纪录提升了一个数量级。相关成果在线发表于国际期刊《自然·光子学》杂志。QKD基于量子力学基本原理，可以实现原理上无条件安全的保密通信，提高成码率对其实用化起着至关重要的作用。高码率可为更多用户提供服务，实现大数据共享、分布式存储加密等高带宽需求的应用。此前国际上最高的实时成码率是每秒10兆比特（10公里标准光纤信道下）。为了实现更高的密钥率，需要解决系统发送端、接收端和后处理等技术瓶颈。在发送端，高码率QKD需要高保真度的量子态调制，然而现有QKD系统在高速调制下会产生较高误码率；在接收端，同时具有高效率和高计数率能力的单光子探测器不可或缺，超导纳米线单光子探测器（SNSPD）具有高效率和低噪声的优点，但其计数率通常受到较长恢复时间的限制。
潘建伟、徐飞虎研究组发展了集成光子片上高速高保真度偏振态调制技术，系统重频达到2.5吉赫兹，量子比特误码率优于0.35%；结合中科院上海微系统所尤立星团队最新研制的八像素SNSPD，实现了高计数率、高效率的单光子探测，在每秒输入5.5亿个光子时仍能保持62%的探测效率；同时，研究组发展了偏振反馈控制、高速后处理模块等。
在上述技术突破的基础上，研究团队实现了10公里标准光纤信道下每秒115.8兆比特的密钥率，较之前纪录提高了约一个数量级；系统稳定运行超过50个小时，在传输距离328公里下码率超过每秒200比特。
研究成果表明，QKD可实现百兆比特率的实时密钥分发，满足高带宽通信需求，对未来量子通信的大规模实际应用具有重要意义。
On March 22, the Chinese scientific research team made a major breakthrough in the field of quantum error correction based on superconducting quantum circuit systems. Through the real-time repeating quantum error correction technology, the storage time of quantum information is extended, surpassing the break-even point for the first time in the world, demonstrating the advantages of quantum error correction. This landmark breakthrough represents a critical step towards practical, scalable, general-purpose quantum computing...
Two more news in the fields related to quantum computing.
The first is about the indigenous ultra-low temporature refrigerating machine specialized for quantum computers passed qualification reviews.
The second is about the mass production of quantum parametric amplifiers developed by Origin Quantum Computing.
The first is about the indigenous ultra-low temporature refrigerating machine specialized for quantum computers passed qualification reviews.
The second is about the mass production of quantum parametric amplifiers developed by Origin Quantum Computing.