标题： 可调节纠缠的交叉帽态作为局部自旋链哈密顿量的精确本征态 显示英文标题

标题： Crosscap states with tunable entanglement as exact eigenstates of local spin chain Hamiltonians

摘要： 最近观察到，各种自旋链哈密顿量都具有特殊的零能“交叉帽”本征态。 这些态由在周期性链的对径位置上制备的最大纠缠贝尔对组成。 我们通过允许对径对具有非最大且可调的纠缠来推广这些态。 我们给出了这些态成为局部哈密顿量精确零能本征态的充分条件。 这些条件在许多具有全局U(1)对称性的模型中自然满足。 这些模型包括著名的可积模型，如XX模型、Bariev模型、折叠的XXZ模型，以及各种不可积模型。 利用零能交叉帽态，我们还推导出了一族具有次体积定律纠缠的精确零模。 显示英文摘要

摘要： It has been observed recently that various spin chain Hamiltonians admit special zero energy "crosscap" eigenstates. These states are made up of maximally entangled Bell pairs prepared on antipodal sites of a periodic chain. We generalize the states by allowing the antipodal pairs to have non-maximal, tunable entanglement. We give sufficient conditions for such states to be exact zero energy eigenstates of a local Hamiltonian. The conditions are naturally satisfied in many models which have a global U(1) symmetry. These models include well known integrable models such as the XX model, the Bariev model, the folded XXZ model, and also a variety of non-integrable models. Using the zero-energy crosscap states we also derive a family of exact zero modes with sub-volume law entanglement.