论文标题
从相互作用淬火中恢复光学晶格中的量子相关性
Recovering quantum correlations in optical lattices from interaction quenches
论文作者
论文摘要
光学晶格中具有超冷原子的量子模拟为理解强烈相互作用的量子系统开辟了一条令人兴奋的途径。原子气显微镜对此至关重要，因为它们提供了单位密度分辨率，在其他量子多体系统中无与伦比。但是，目前对局部连贯电流进行直接测量是无法触及的。在这项工作中，我们通过测量响应于非相互作用动力学的淬火而（例如，在倾斜光学晶格之后）的密度来展示如何实现这一目标。为此，我们建立了一个数据分析方法，以求解与隧道电流和原子数动力学相关的封闭方程组，从而可靠地恢复了完整的协方差矩阵，包括代表相干电流的非对角线项。信号处理基于半明确的优化，提供了真正与观察到的数据相匹配的真正的协方差矩阵。我们展示了获得的有关非公认可观察物的信息如何允许在有限温度下下限纠缠，从而开辟了研究量子模拟中量子相关性超出经典能力的可能性。
Quantum simulations with ultra-cold atoms in optical lattices open up an exciting path towards understanding strongly interacting quantum systems. Atom gas microscopes are crucial for this as they offer single-site density resolution, unparalleled in other quantum many-body systems. However, currently a direct measurement of local coherent currents is out of reach. In this work, we show how to achieve that by measuring densities that are altered in response to quenches to non-interacting dynamics, e.g., after tilting the optical lattice. For this, we establish a data analysis method solving the closed set of equations relating tunnelling currents and atom number dynamics, allowing to reliably recover the full covariance matrix, including off-diagonal terms representing coherent currents. The signal processing builds upon semi-definite optimization, providing bona fide covariance matrices optimally matching the observed data. We demonstrate how the obtained information about non-commuting observables allows to lower bound entanglement at finite temperature which opens up the possibility to study quantum correlations in quantum simulations going beyond classical capabilities.
