近日，中国科学技术大学的潘建伟&苑震生及其研究团队取得一项新进展。他们揭示了双组分莫特绝缘子的逆流超流动性。相关研究成果已于2025年1月8日在国际知名学术期刊《自然—物理学》上发表。
本文报道了在光晶格中的二元玻色混合物中观察到了逆流超流动性。研究人员通过将每个晶格位点上的两个自旋-1/2玻色原子传送形成双占据态，从而制备出低熵自旋-莫特态后，将系统绝热地驱动至约1nK的逆流超流体相。
研究人员利用位点和自旋分辨的量子气体显微镜，在实空间和动量空间中都观察到了反配对关联的特征。最后，研究人员在旋转基下测量了长程非对角自旋关联，揭示出关联长度接近系统尺寸。这里展示的技术和观察结果为探索博罗梅安逆流超流体提供了可行性。
据悉，逆流超流动性是一种奇异的量子相，二十年前在双组分玻色–哈伯德模型的背景下被预测出来。在这种相中，尽管两个组分都表现出流动性，但它们的相关逆流电流关联抵消，导致系统表现为不可压缩的莫特绝缘体。然而，由于单一实验装置对缺陷无状态的制备、相干操作过程中最小的加热以及相位的自旋和位点分辨检测等严格要求，实验上实现和识别这种相一直具有挑战性。
附：英文原文
Title: Counterflow superfluidity in a two-component Mott insulator
Author: Zheng, Yong-Guang, Luo, An, Shen, Ying-Chao, He, Ming-Gen, Zhu, Zi-Hang, Liu, Ying, Zhang, Wei-Yong, Sun, Hui, Deng, Youjin, Yuan, Zhen-Sheng, Pan, Jian-Wei
Issue&Volume: 2025-01-08
Abstract: Counterflow superfluidity is an anomalous quantum phase that was predicted two decades ago in the context of a two-component Bose–Hubbard model. In this phase, although both components exhibit fluidity, their correlated counterflow currents cancel each other out, resulting in the system behaving as an incompressible Mott insulator. However, realizing and identifying this phase experimentally has proven challenging due to the stringent requirements for a single set-up, including defect-free state preparation, minimal heating during coherent manipulations, and spin- and site-resolved detection of the phases. Here, we report on the observation of counterflow superfluidity in a binary Bose mixture in optical lattices. After preparing a low-entropy spin-Mott state by conveying two spin-1/2 bosonic atoms at every single lattice site to form a doublon, we adiabatically drove the system to the counterflow superfluid phase at approximately 1nK. We observed features of antipair correlations through site- and spin-resolved quantum-gas microscopy in both real and momentum spaces. Finally, we measured long-range off-diagonal spin correlations in the rotated basis, revealing a correlation length approaching the system size. These techniques and observations demonstrated here provide accessibility to Borromean counterfluids.
DOI: 10.1038/s41567-024-02732-5
Source: https://www.nature.com/articles/s41567-024-02732-5