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多光子非线性量子干涉首次实现 为新型量子态制备等应用奠定基础******
科技日报合肥1月16日电 (记者吴长锋)记者16日从中国科学技术大学获悉，该校郭光灿院士团队任希锋研究组与国外同行合作，基于光量子集成芯片，在国际上首次展示了四光子非线性产生过程的干涉。相关成果日前发表在光学权威学术期刊《光学》上。
量子干涉是众多量子应用的基础，特别是近年来基于路径不可区分性产生的非线性干涉过程越来越引起人们的关注。尽管双光子非线性干涉过程已经实现了20多年，并且在许多新兴量子技术中得到应用，直到2017年，人们才在理论上将该现象扩展到多光子过程，但实验上由于需要极高的相位稳定性和路径重合性，一直未获得新进展。光量子集成芯片，以其极高的相位稳定性和可重构性逐渐发展成为展示新型量子应用、开发新型量子器件的理想平台，也为多光子非线性干涉研究提供了实现的可能性。
任希锋研究组长期致力于硅基光量子集成芯片开发及相关应用研究并取得系列重要进展。在前工作基础上，研究组通过进一步将多光子量子光源模块、滤波模块和延时模块等结构片上级联，在国际上首次展示了四光子非线性产生过程的相干相长、相消过程，其四光子干涉可见度为0.78。而双光子符合并未观测到随相位的明显变化，这同理论预期一致。整个实验在一个尺寸仅为3.8×0.8平方毫米的硅基集成光子芯片上完成。
这一成果成功地将两光子非线性干涉过程扩展到多光子过程，为新型量子态制备、远程量子计量以及新的非局域多光子干涉效应观测等应用奠定了基础。审稿人一致认为这是一个重要的研究工作，并给出了高度评价：该芯片设计精良，包含多种集成光学元件，如纠缠光子源、干涉仪、频率滤波器/组合器；这项工作推动了集成光子量子信息科学与技术研究领域的发展。
中新网评：处理核污水绝不是日本自家私事******
中新网北京1月19日电(蒋鲤)日本政府近日称，将于2023年春夏期间开始向海洋排放经过处理的福岛第一核电站核污水。日本罔顾国内民众及周边国家的屡屡反对，企图将核污水“一倒了之”，把一件关乎全球海洋生态环境和公众健康的事当成了自家私事。
资料图：日本福岛第一核电站。2011年，福岛核电站事故发生后，大量放射性物质泄漏到大气层和太平洋，对周围环境造成了难以逆转的伤害，数十万人被迫撤离该地区。时至今日，作为日本邻国之一的韩国仍未解除福岛海鲜禁令。
日本以核污水存储能力即将达到上限为由，在2021年4月13日，正式决定将福岛第一核电站核污水排入太平洋。过去一年多，日本政府和东京电力公司一直在持续推进核污水排海计划。
日本政府辩称，这些核污水经多核素处理系统(ALPS)处理后很安全，甚至“可以喝”，这样的表态无疑在愚弄大众。
事实上，经过处理的核污水仍含有多种放射性物质，核污水一旦排放入海就无法回收，长期来看，将会给海洋生态带来难以估量的潜在威胁，最终危害人类健康。
因此，核污水排海计划推出后，遭到日本民众强烈反对。日本《朝日新闻》2022年3月公布的问卷调查显示，福岛县、宫城县和岩手县受访的42个市町村长中，约六成反对东京电力公司福岛第一核电站核污水排放入海。日本全国渔业协会联合会也多次申明立场，反对该计划。
日本政府认为，核污水排海是最便宜、最省事的解决方案，但此举却将周边国家乃至全世界置于核污染风险中。太平洋非日本一家之海，核污水会随着洋流流动，其影响势必会跨越国界，危害周边国家乃至整个国际社会的公共福祉和利益。
《韩国经济新闻》发文称，相关研究认为，福岛核污水如果排放入海，约7个月后将到达济州等韩国海域，该国水产业和旅游业将遭受相当大的损失。
德国南极海洋机构也曾发出警告，若日本将所有核污水排入海中，不到半年，整个太平洋都将面临高度辐射威胁，包括远在大洋另一端的美国。太平洋地区人民更是对日本该计划持反对意见。
日本作为《联合国海洋法公约》缔约国，有义务保护海洋环境。然而，在核污水排海方案的正当性、核污水数据的可靠性、净化装置的有效性、环境影响的不确定性等问题上，日本未能作出科学、可信的说明。
国际原子能机构技术工作组虽已三次赴日实地考察评估，但尚未就日排海方案的安全性给出结论，并且对日本提出诸多澄清要求和整改意见。在此情况下，日本仍执意推进核污水排海工程建设，这是极不负责任的行为。
太平洋不是日本的下水道，日本必须正视各方合理关切，在与周边国家等相关利益方和国际原子能机构充分协商后，制定合理的核污水处理方案。日本也要着眼长远，若只顾眼前，执意将核污水排放入海，不仅其自身，周边国家乃至全世界都将为之买单，其后果必将会危害数代人。
Fukushima water disposal by no means Japan’s own business
By John Lee
(ECNS) -- Japan has announced it will release treated wastewater from the wrecked Fukushima Daiichi Nuclear Power Plant into the Pacific Ocean this year.
Although Fukushima wastewater disposal affects global marine ecological environment protection and public health, Japan has turned a deaf ear to domestic and international opposition to dumping the contaminated water into the sea, treating the "global" matter as its own business.
The Fukushima accident in 2011 had sent large quantities of radiation into the atmosphere and the Pacific Ocean, causing irreversible damage to the surrounding environment, and hundreds of thousands of people were forced to evacuate the area. South Korea still maintains its import ban on Japanese seafood from areas affected by the Fukushima nuclear disaster.
On April 13, 2021, Japan announced it had decided to discharge contaminated radioactive wastewater in Fukushima Prefecture into the sea due to dwindling storage space, with the Japanese government and plant operator Tokyo Electric Power Company Holdings Inc. promoting the release plan over the past year.
The Japanese government argues that the water treated by an advanced liquid processing system, or ALPS, is safe and drinkable, which is undoubtedly fooling the public.
In fact, the treated wastewater still includes a variety of radioactive substances and can’t be recycled once discharged into the sea, which will pose a great threat to marine ecology and ultimately endanger human health in the long run.
Therefore, the discharge plan has been strongly opposed in Japan. According to a questionnaire conducted by The Asahi Shimbun, nearly 60 percent of mayors of 42 municipalities in Iwate, Miyagi and Fukushima prefectures oppose the discharge plan. The National Fisheries Cooperative Federation of Japan has also repeatedly stated its opposition in public.
The Japanese government believes that dumping Fukushima wastewater into the sea is the cheapest and most convenient solution, but neighboring countries and even the whole world will be at risk of nuclear pollution.
The Pacific Ocean doesn’t belong to Japan and the wastewater flow along oceanic currents will surely break boundaries and endanger public welfare and the interests of neighboring countries and even the international community.
The Korea Economic Daily reported that related research concluded that if contaminated water from Fukushima is released into the ocean, it would only take seven months for the contaminated water to reach the shores of Jeju Island, with the country's aquaculture and tourism suffering considerable losses.
According to the calculation of a German marine scientific research institute, radioactive materials will spread to most of the Pacific Ocean within half a year from the date of discharge, and the U.S. and Canada will be affected by nuclear pollution. People in the Pacific region also oppose the discharge plan.
As a participant of the United Nations Convention on the Law of the Sea, Japan has the obligation of protecting the marine environment.
However, it hasn’t offered a full and convincing explanation on issues like the legitimacy of the discharge plan, the reliability of data on the nuclear-contaminated water, the efficacy of the treatment system or the uncertainty of environmental impact.
Though the IAEA has yet to complete a comprehensive review after three investigations in Japan, the Japanese side has been pushing through the approval process for its discharge plan and even started building facilities for the discharge. It is rather irresponsible for Japan to act against public opinion at home and concerns abroad.
The Pacific Ocean is not a private Japanese sewer. The country must seriously heed the voices of the international community and make a reasonable plan for the Fukushima wastewater disposal after full consultation with stakeholders and international agencies.
If it only seeks instant interest and insists on discharging the contaminated water into the sea, not only itself, but also its neighboring countries and the entire world will pay for the decision and several generations will be forced to bear the consequence.
（文图：赵筱尘 巫邓炎） [责编：天天中] 阅读剩余全文（）  视觉焦点
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