香港大學物理學家發(fā)現高度糾纏的量子物質的特征
指南者留學
2022-07-21 17:39:21
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<div class="ace-line ace-line old-record-id-doxcnEw26ggOe8W0Sg9DJZ0aREb" style="text-align: center;"><span class="h6">圖1:部分研究團隊的照片。左起:鄭燕博士、趙佳瑞先生、陳斌斌博士。</span></div>
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<div class="ace-line ace-line old-record-id-doxcnUi2A6ciYySeoOgPDh5NN2e" style="text-align: center;"><span class="h6">圖2:數值實驗示意圖。</span></div>
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<div class="ace-line ace-line old-record-id-doxcnEueeiSioMqEiiyZyb3iBp8" style="text-align: center;"><span class="h6">圖3:可果美量子自旋模型的晶格類型及拓撲熵的相應結果。</span></div>
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<div class="ace-line ace-line old-record-id-doxcnoqgSeIIqayyssfgEsF24xf" style="text-align: justify;"><span class="p">來自香港大學(HKU)物理系的一個研究小組從超級計算機上的大規(guī)模模擬中發(fā)現了表征高度糾纏的量子物質的明確證據 - 量子自旋液體(QSL)(即使在非常低的溫度下仍然無序的物質相)。 這項關鍵的研究工作最近發(fā)表在量子材料的主要期刊之一<em>npj量子材料</em>上。</span></div>
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<div class="ace-line ace-line old-record-id-doxcnyaEM2OQiUIUGyGalZ1UyMc" style="text-align: justify;"><span class="p">QSL是由1977年諾貝爾物理學獎獲得者P.W.安德森(P. W. Anderson)于1973年提出的,它有可能用于拓撲量子計算,將計算機的計算能力提升到一個新的階段,并幫助理解高溫超導體的機制,從而大大降低電力傳輸過程中的能源成本。 由于超導體中沒有電阻。</span></div>
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<div class="ace-line ace-line old-record-id-doxcnsqkWA66WG0YGeUYMv2H11f" style="text-align: justify;"><span class="p">QSL被稱為液體,因為它在這件事上缺乏常規(guī)順序。QSL具有起源于長距離和強量子糾纏的拓撲順序,而由于缺乏能夠完美實現科學家提出的許多模型系統的材料,以找到QSL的拓撲順序并證明其存在,因此檢測該拓撲順序是一項非常艱巨的任務。因此,尚未被明確接受的具體證據表明QSL在自然界中存在。</span></div>
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<div class="ace-line ace-line old-record-id-doxcngkUoswCKUKmwCAit2XXyNh" style="text-align: justify;"><span class="p">在此背景下,來自香港大學物理系的趙佳瑞先生、陳斌斌博士、鄭岱博士和孟子洋博士在可果美晶格量子自旋模型的一個階段成功探測了這一拓撲階次,該模型是一種具有內在量子糾纏的二維晶格模型,由具有Z的科學家提出。(2)(2階的循環(huán)群)拓撲順序,通過在超級計算機上精心設計的數值實驗。拓撲糾纏熵的明確結果強烈表明,從數值角度來看,QSL存在于高度糾纏量子模型中。</span></div>
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<div class="ace-line ace-line old-record-id-doxcnSOMoKU8cU4eSofL8M2hb1b" style="text-align: justify;"><span class="p">“我們的工作利用了現代超級計算機的卓越計算能力,我們用它們來模擬一個非常復雜的模型,該模型被認為具有拓撲順序。根據我們的發(fā)現,物理學家更有信心QSL應該存在于自然界中,“該期刊論文的第一作者,物理系博士生趙佳瑞先生說。</span></div>
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<div class="ace-line ace-line old-record-id-doxcnw2icUASkOY2McnuLYaewye" style="text-align: justify;"><span class="p">“數值模擬一直是量子材料科學研究的重要趨勢。我們的算法和計算可以找到更有趣和新穎的量子物質,這些努力肯定會有助于實用量子技術和基礎研究新范式的發(fā)展。物理系副教授子陽萌博士說。 研究團隊設計了一個關于可果美自旋模型的數值實驗(可果美是一種二維晶格結構,顯示出與日本傳統竹子編織圖案相似的圖案,形狀為六角形格子。),實驗示意圖如圖2所示。系統的糾纏熵(S)可以通過測量模型的自由能在精心設計的非平衡過程中的變化來獲得。表征長程拓撲階的拓撲熵(γ)可以通過將不同糾纏邊界長度的糾纏熵數據擬合到一條直線(S=al-γ)來減去與總糾纏熵(S)中糾纏邊界(l)的長度成正比的短程貢獻來提取。</span></div>
<div class="ace-line ace-line old-record-id-doxcnSoMqEMYioeWo6XGMSm5C0e" style="text-align: justify;"><span class="p">如圖3所示,研究小組對兩種長度和寬度不同比例的晶格進行了實驗,以確保結果的可靠性。我們使用一條直線來擬合糾纏熵與糾纏邊界長度之間的關系,以便拓撲熵應等于直線的截距。我們的結果給出的拓撲熵值為1.4(2),這與Z2量子自旋液體的拓撲熵預測值一致,即2ln(2)。我們的研究結果從數值角度證實了QSL的存在。</span></div>
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<div class="ace-line ace-line old-record-id-doxcnOGsQmqKgUGsCqLuDKXbfqb" style="text-align: justify;"><span class="p"><strong>關于研究團隊</strong></span></div>
<div class="ace-line ace-line old-record-id-doxcnCCYaouIomowqGQhINqnDjc" style="text-align: justify;"><span class="p">這項研究是三位作者之間的合作成果 - 來自香港大學物理系的趙佳瑞先生,陳斌斌博士和鄭燕博士,在來自同一隸屬關系的Zi Yang Meng博士的監(jiān)督下。</span></div>
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<div class="ace-line ace-line old-record-id-doxcnQq8uEusOqsYyeyjbQMTBYe" style="text-align: justify;"><span class="p">這項工作得到了香港特別行政區(qū)研究資助局卓越領域“二維材料研究:新興技術的基礎”的支持,以及香港大學-TCL人工智能聯合研究中心的種子資助量子啟發(fā)可解釋性人工智能。我們感謝香港大學信息技術服務部和HPC2021超級計算機,以及廣州國家超級計算機中心(天河二號超級計算機)的技術支持和慷慨的HPC資源,為本文報告的研究成果做出了貢獻。</span></div>
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