标题： 在LHC测量量子失谐 显示英文标题

标题： Measuring Quantum Discord at the LHC

摘要： 在对撞机中探索与量子信息相关的量引起了越来越多的兴趣。 我们详细分析了如何在大型强子对撞机（LHC）中测量顶夸克-反顶夸克量子态中的量子失谐。 对于纯态而言，量子失谐、纠缠和贝尔非定域性都探测相同的关联；而对于混合态，它们则探测量子关联的不同方面。 特别是量子失谐很有趣，因为它旨在包含所有不能具有经典起源的系统之间的关联。 我们采用两种互补的方法来研究顶夸克-反顶夸克系统，即衰变方法和运动学方法。 我们强调了在对撞机中测量重建量子态的失谐时所涉及的微妙之处。 通常由于必须执行的极值化过程，量子失谐难以计算。 然而，我们展示了对于 $t\bar{t}$ 系统，这种极值化可以解析地完成，并且我们提供了量子失谐的闭合公式。 我们证明，在高亮度LHC中，使用衰变方法，失谐可以以约5%的精度测量，而使用运动学方法则可以达到亚百分比水平。 即使使用目前的LHC数据集，运动学方法也可以将失谐测量到1-2%的精度。 通过首次通过详细的对撞机分析系统研究量子失谐，这项工作扩展了粒子物理学中量子信息研究的工具包，并为深入了解高能碰撞中的量子性质奠定了基础。 显示英文摘要

摘要： There has been an increasing interest in exploring quantities associated with quantum information at colliders. We perform a detailed analysis describing how to measure the quantum discord in the top anti-top quantum state at the Large Hadron Collider (LHC). While for pure states, quantum discord, entanglement, and Bell nonlocality all probe the same correlations, for mixed states they probe different aspects of quantum correlations. The quantum discord, in particular, is interesting because it aims to encapsulate all correlations between systems that cannot have a classical origin. We employ two complementary approaches for the study of the top anti-top system, namely the decay method and the kinematic method. We highlight subtleties associated with measuring discord for reconstructed quantum states at colliders. Usually quantum discord is difficult to compute due to an extremization that must be performed. We show, however, that for the $t\bar{t}$ system this extremization can be performed analytically and we provide closed-form formulas for the quantum discord. We demonstrate that at the high luminosity LHC, discord is projected to be measurable with a precision of approximately 5% using the decay method and sub-percent levels using the kinematic method. Even with current LHC datasets, discord can be measured with 1-2% precision with the kinematic method. By systematically investigating quantum discord for the first time through a detailed collider analysis, this work expands the toolkit for quantum information studies in particle physics and lays the groundwork for deeper insights into the quantum properties in high-energy collisions.