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“秒”要被重新定义了 潘建伟团队这项“国际首次”研究功不可没_我的网站

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根据实验结果来看，研究有效验证了星地链路高精度光频标比对的可行性，向建立广域光频标网络迈出重要一步。    WARSAW, Poland -- Polish opposition leader Donald Tusk declared the beginning of a new era for his country after opposition parties appeared to have won enough votes in Sunday's parliamentary election to oust the governing nationalist conservative party.That party, Law and Justice, has bickered with allies and faced accusations of eroding rule of law at home in its eight years in power. It appeared that voters were mobilized like never before, voting in even greater numbers than when the nation ousted the communist authorities in 1989. In some places people were still in line when polling officially closed, but all were allowed to vote. If the result predicted by an exit poll holds, Law and Justice won but also lost. It got more seats than any other party but not enough to be able to lead a government that can pass laws in the legislature. The Ipsos exit poll suggested that Law and Justice obtained 200 seats. Its potential partner, the far-right Confederation got 12 seats, a showing the party acknowledged was a defeat.It also showed that three opposition parties have likely won a combined 248 seats in the 460-seat lower house of parliament, the Sejm. The largest of the groups is Civic Coalition, led by Tusk, a former prime minister and former European Union president. It won 31.6% of votes, the exit poll said. “I have been a politician for many years. I’m an athlete. Never in my life have I been so happy about taking seemingly second place. Poland won. Democracy has won. We have removed them from power,” Tusk told his cheering supporters.“This result might still be better, but already today we can say this is the end of the bad time, this is end of Law and Justice rule," Tusk added.Law and Justice leader Jaroslaw Kaczynski acknowledged the ambiguous result. He told supporters at his headquarters that his party’s result, at nearly 37% of the vote, according to the exit poll, was a success, making it the party to win the most votes for three parliamentary elections in a row. “We must have hope and we must also know that regardless of whether we are in power or in the opposition, we will implement this (political) project in various ways and we will not allow Poland to be betrayed," Kaczynski said.If the result holds, and Law and Justice is the single party with the most seats, then it would most likely get the first chance to try to build a government.It falls to President Andrzej Duda, who is an ally of Law and Justice, to tap a party to try to form a government.Prime Minister Mateusz Morawiecki said on Polsat News that Duda “will entrust the mission of forming the government to the winning party and in this first step we will certainly try to build a parliamentary majority."Three opposition parties, Tusk's Civic Coalition, Third Way and the New Left, ran on separate tickets but with the same promises of seeking to oust Law and Justice and restore good ties with the European Union.Wlodzimierz Czarzasty, a leader of the Left party, vowed to work with the others to “create a democratic, strong, reasonable and predictable government.”Katarzyna Pelczynska-Nalecz, the head of election campaign for Third Way, called it a “huge day for our democracy.”Votes were still being counted and the state electoral commission says it expects to have final results by Tuesday morning.At stake are the health of the nation’s constitutional order, its legal stance on LGBTQ+ rights and abortion, and the foreign alliances of a country that has been a crucial ally to Ukraine after Russia launched its full-scale invasion.LGBTQ+ rights activist Bart Staszewski called it the end of a “nightmare” for himself as a gay man and others.“This is just the beginning of reclaiming of our country. The fight is ahead but we are breathing fresh air today,” Staszewski said.Environmental activist Dominika Lasota was emotional with relief, saying “we have our future.”Law and Justice has eroded checks and balances to gain more control over state institutions, including the courts, public media and the electoral process itself.During the campaign many Poles described the vote as the most important one since 1989, when a new democracy was born after decades of communism.Turnout Sunday appeared to be even higher than the 63% of voters who turned out for the 1989 election that led to the ouster of the communists. Despite many uncertainties ahead, what appeared certain was that support for the governing party has shrunk since the last election in 2019 when it won nearly 44% of the vote, its popularity dented by high inflation, allegations of cronyism and bickering with European allies.There is a high level of state ownership in the Polish economy, and the governing party has built up a system of patronage, handing out thousands of jobs and contracts to its loyalists. A political change could open the way for the EU to release billions of euros in funding that has been withheld over what the EU viewed as democratic erosion.Piotr Buras, of the European Council of Foreign Relations, said the opposition had gained from “growing fatigue” with the government among Poles, "beyond the groups usually supporting the liberals.” The fate of Poland's relationship with Ukraine was also at stake. The Confederation party campaigned on an anti-Ukraine message, accusing the country of lacking gratitude to Poland for its help in Russia's war. Its poor showing will be a relief for Kyiv.A referendum on migration, the retirement age and other issues was held simultaneously. Some government opponents called on voters to boycott the referendum, saying it was an attempt by the government to galvanize its supporters. Many voters were seen refusing to take part in the referendum.___Associated Press journalists Kwiyeon Ha, Pietro De Cristofaro and Rafal Niedzielski contributed to this report.。对此，中国科学技术大学张强教授表示：将来如果放在卫星上能做洲际的时间比对，我们就可以实现新一代的“秒”定义。为什么“秒”要被重新定义了？咱们现在经常提到的时间概念“秒”，是自 1976 年以来，一直由铯-33 原子钟来定义的。原子钟最初是英国物理学家 Louis Esseb 创造，它的工作原理是计算原子中的电子自旋的翻转频率。

B | 而在 1976 年这一年，科学家们通过铯-133 原子在微波频率下的跳动，重新定义了这个时间基本单位：1 秒 = 铯原子的电子自旋翻转 9192631770 次的持续时间。虽然说这种方式已经够精确了，但科学家们似乎却不满足于此。截至目前，自然领域中对时间的测量精度已经步入 10-19 的量级。

C | 这种量级通俗点来讲，就是百亿年期间误差不会超过 1 秒。而且时间是目前七大基本物理量中测量最精确的那一个。但单有最精确的计时还是不够的，因为它还需要“配套”一个与之精度相匹配的时间传递技术。二者的重要性可以说是画等号的。但地面附近自由空间的环境复杂，大气中的各种扰动、湍流、链路损耗、环境变化等因素，给自由空间长距离时频传递带来了极大困难。此前，自由空间中的光频传输技术只能实现 10 公里量级的传输。而潘建伟团队要攻克的正是这一难题：在光源方面，研制出高功率、高稳定度光输。在光信号收发信道方面，研制出高稳定性、高效率的光收发望远镜系统。

D | 还采用线性光学采样的干涉测量方式，实现了高精度的时间测量。最终，潘建伟团队在相隔 113 公里的新疆南山天文台和高崖子天文台之间，实现了万秒 10-19 量级稳定度的时频传递。
据张强介绍：把我们非常精密的这种时间信号，通过这个望远镜打到这个 100 公里以外的另外一个望远镜。

E | 那边的话，然后我的这个信号被那边的一个同样的一个望远镜接收，接收了之后他们进行一些比较精密的时间探测。同时那边也会打一个同样的一个精密的光源信号也打过来，在这边也做一个同样的一个精密探测，然后两边的信号再做一个对准，做一个校正。
据了解，该实验在如此自由空间时频传递过程中：时间传递万秒稳定度达到飞秒量级，频率传递万秒稳定度优于 4E-19，系统相对偏差为 6.3E-20±3.4E-19，系统可容忍最大链路损耗高达 89dB，远高于中高轨星地链路损耗的典型预期值（约 78dB）。
而国际计量组织计划 2026 年讨论“秒”定义的变更，也正因这项研究成果的实现，张强认为：如果能够实现洲际的比对的话，那么我们就可以实现新一代的这个“秒”定义。与日常生活相关那么接下来的一个问题便是，这项研究成果会带来哪些影响？引用 Nature 审稿人的评价就是：该工作是星地自由空间远距离光学时间频率传递领域的一项重大突破，将对暗物质探测、物理学基本常数检验、相对论检验等基础物理学研究产生重要影响。但除此之外，其实这项研究也与人们的日常生活息息相关。例如卫星的导航精度与计时精度紧密相关，若是希望定位更加准确（毫米以下），就需要更好的计时精度。在大地测量、地质勘探、雷达探测等涉及社会民生的领域，精确的时间也都将发挥重要的作用。那么对于未来新“秒”的定义，你期待了吗？参考链接：[1]https://www.nature.com/articles/s41586-022-05228-5[2]https://weibo.com/2032139271/Mb1zivEhA?type=comment[3]https://mp.weixin.qq.com/s/MCbQ6UJFNflzF0VmrtPw4Q[4]https://tv.cctv.com/2022/10/06/VIDEYEjxB0UTcY85WichtWvz221006.shtml?spm=C45404.PCHhhgX3efBE.Ev0XVtu8CoWN.224[5]https://ishare.ifeng.com/c/s/v002EZ3vLgfck1LPf29qCKM51b4D1bqKqLDSTFiDq8nGUgw__。

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