Liang Libo, Zheng Wei, Yao Ruixiao, Zheng Qinpei, Yao Zhiyuan, Zhou Tian-Gang, Huang Qi, Zhang Zhongchi, Ye Jilai, Zhou Xiaoji, Chen Xuzong, Chen Wenlan, Zhai Hui, Hu Jiazhong
School of Electronics, Peking University, Beijing 100871, China.
Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China.
Sci Bull (Beijing). 2022 Dec 31;67(24):2550-2556. doi: 10.1016/j.scib.2022.12.005. Epub 2022 Dec 5.
Ramping a physical parameter is one of the most common experimental protocols in studying a quantum system, and ramping dynamics has been widely used in preparing a quantum state and probing physical properties. Here, we present a novel method of probing quantum many-body correlation by ramping dynamics. We ramp a Hamiltonian parameter to the same target value from different initial values and with different velocities, and we show that the first-order correction on the finite ramping velocity is universal and path-independent, revealing a novel quantum many-body correlation function of the equilibrium phases at the target values. We term this method as the non-adiabatic linear response since this is the leading order correction beyond the adiabatic limit. We demonstrate this method experimentally by studying the Bose-Hubbard model with ultracold atoms in three-dimensional optical lattices. Unlike the conventional linear response that reveals whether the quasi-particle dispersion of a quantum phase is gapped or gapless, this probe is more sensitive to whether the quasi-particle lifetime is long enough such that the quantum phase possesses a well-defined quasi-particle description. In the Bose-Hubbard model, this non-adiabatic linear response is significant in the quantum critical regime where well-defined quasi-particles are absent. And in contrast, this response is vanishingly small in both superfluid and Mott insulators which possess well-defined quasi-particles. Because our proposal uses the most common experimental protocol, we envision that our method can find broad applications in probing various quantum systems.
对物理参数进行斜坡式变化是研究量子系统时最常见的实验方案之一，斜坡式变化动力学已被广泛用于制备量子态和探测物理性质。在此，我们提出一种通过斜坡式变化动力学来探测量子多体关联的新方法。我们将哈密顿量参数从不同的初始值以不同的速度斜坡式变化到相同的目标值，并且我们表明，有限斜坡速度下的一阶修正具有普遍性且与路径无关，这揭示了目标值处平衡相的一种新型量子多体关联函数。我们将此方法称为非绝热线性响应，因为这是绝热极限之外的主导阶修正。我们通过在三维光学晶格中研究超冷原子的玻色 - 哈伯德模型来实验性地演示此方法。与揭示量子相的准粒子色散是有能隙还是无能隙的传统线性响应不同，这种探测对准粒子寿命是否足够长从而使量子相具有明确的准粒子描述更为敏感。在玻色 - 哈伯德模型中，这种非绝热线性响应在不存在明确准粒子的量子临界区域中很显著。相反，在具有明确准粒子的超流体和莫特绝缘体中，这种响应都非常小。由于我们的提议使用了最常见的实验方案，我们设想我们的方法能够在探测各种量子系统中找到广泛的应用。
