标题： 密度矩阵重整化群对域壁量子比特的研究 显示英文标题

标题： Density Matrix Renormalization Group Study of Domain Wall Qubits

摘要： 纳米尺度的拓扑自旋纹理在磁性系统中正成为可扩展量子架构的有前途的候选者。 尽管它们作为量子比特的潜力，以往的研究仅限于半经典方法，留下了一个关键空白：缺乏完全的量子演示。 在此，我们通过采用密度矩阵重整化群（DMRG）方法来在耦合的量子自旋-1/2链中建立畴壁（DW）量子比特。 我们计算了系统的基态能量和激发能隙，并发现具有相反手性的畴壁形成一个明确的低能区，在各向异性存在的情况下，该区与更高激发态明显隔离。 这使得手性状态适合编码量子信息，作为稳健的量子比特。 有趣的是，当施加磁场时，我们观察到具有相反手性的量子畴壁状态之间的隧穿。 通过量子模拟，我们构建了一个有效量子比特哈密顿量，表现出强各向异性的$g$-因子，提供了一种实现单量子比特门的方法。 此外，我们从DMRG模拟中获得了耦合量子自旋链中两个移动畴壁的有效相互作用哈密顿量，从而实现了双量子比特门。 我们的工作标志着从半经典构造向完全量子演示的重要一步，展示了畴壁纹理在可扩展量子计算中的潜力，为基于拓扑磁纹理的未来量子架构奠定了坚实的基础。 显示英文摘要

摘要： Nanoscale topological spin textures in magnetic systems are emerging as promising candidates for scalable quantum architectures. Despite their potential as qubits, previous studies have been limited to semiclassical approaches, leaving a critical gap: the lack of a fully quantum demonstration. Here, we address this challenge by employing the density-matrix renormalization group (DMRG) method to establish domain wall (DW) qubits in coupled quantum spin-1/2 chains. We calculate the ground-state energies and excitation gaps of the system and find that DWs with opposite chiralities form a well-defined low-energy sector, distinctly isolated from higher excited states in the presence of anisotropies. This renders the chirality states suitable for encoding quantum information, serving as robust qubits. Interestingly, when a magnetic field is applied, we observe tunneling between quantum DW states with opposite chiralities. Through quantum simulations, we construct an effective qubit Hamiltonian that exhibits strongly anisotropic $g$-factors, offering a way to implement single-qubit gates. Furthermore, we obtain an effective interacting Hamiltonian for two mobile DWs in coupled quantum spin chains from DMRG simulations, enabling the implementation of two-qubit gates. Our work represents a critical step from semiclassical constructions to a fully quantum demonstration of the potential of DW textures for scalable quantum computing, establishing a solid foundation for future quantum architectures based on topological magnetic textures.