Experimental characterization of a quantum many-body system via higher-order correlations
Experimental characterization of a quantum many-body system via higher-order correlations
复制标题
DOI：
10.1038/nature22310
复制
发表时间：
2015-05
期刊：
影响因子：
64.8
通讯作者：
T. Schweigler;V. Kasper;Sebastian Erne;I. Mazets;B. Rauer;Federica Cataldini;T. Langen;T. Gasenzer;J. Berges;J. Schmiedmayer
中科院分区：
文献类型：
--
作者：
T. Schweigler;V. Kasper;Sebastian Erne;I. Mazets;B. Rauer;Federica Cataldini;T. Langen;T. Gasenzer;J. Berges;J. Schmiedmayer
了解一个系统的所有关联函数等价于解决相应的多体问题。如果关联因式分解，至少是近似的，那么有限的关联函数集就足以描述量子多体系统。虽然这是一个强大的理论概念，但基于实验数据的实施到目前为止仍然难以捉摸。在这里，这是通过将其应用于一个非平凡的量子多体问题来实现的：一对隧道耦合的一维原子超流体。我们从测量的干涉图样中提取高达10阶的相位相关函数，并分析它们是否以及在什么条件下分解。这表征了系统的基本特征，相关的准粒子，它们的相互作用，以及可能的拓扑结构上不同的真空。我们证实，在热平衡下，物理可以用量子Sine-Gordon模型来描述，该模型与从粒子到凝聚态物理的各种学科相关。我们的实验建立了一种在实验中分析量子多体系统的通用方法。它是实现和验证量子模拟器的关键因素。
Knowledge of all correlation functions of a system is equivalent to solving the corresponding many-body problem. Already a finite set of correlation functions can be sufficient to describe a quantum many-body system if correlations factorise, at least approximately. While being a powerful theoretical concept, an implementation based on experimental data has so far remained elusive. Here, this is achieved by applying it to a non-trivial quantum many-body problem: A pair of tunnel-coupled one-dimensional atomic superfluids. From measured interference patterns we extract phase correlation functions up to tenth order and analyse if, and under which conditions, they factorise. This characterises the essential features of the system, the relevant quasiparticles, their interactions and possible topologically distinct vacua. We verify that in thermal equilibrium the physics can be described by the quantum sine-Gordon model, relevant for a wide variety of disciplines from particle to condensed-matter physics. Our experiment establishes a general method to analyse quantum many-body systems in experiments. It represents a crucial ingredient towards the implementation and verification of quantum simulators.