标题： 量子Skyrmion量子比特在三角晶格磁体中 显示英文标题

标题： Quantum Skyrmion Qudit in a Triangular-lattice magnet

摘要： 自Lohani等人在Phys. Rev. X 9, 041063 (2019)的开创性工作以来，人们清楚地认识到，与经典skyrmion相比，量子skyrmion具有高度不寻常的特性，并且由于其量子性，不能像经典skyrmion那样用连续的磁纹理来描述。三角形自旋受挫磁体中竞争的最近邻和次近邻铁磁和反铁磁相互作用导致了量子skyrmion态的形成。在受挫磁体中，skyrmion由螺旋自由度表征，可以存储量子信息。在弱电场极限下，系统可以描述为一个两能级系统，即一个skyrmion量子比特。在这里，我们提出了一个问题的更一般的表述，并得到了之前在Psaroudaki等人在Phys. Rev. Lett. 127, 067201 (2021)中引入的模型的一般解析解。我们的解不仅适用于小势垒，也适用于任意电场。在存在显著势垒的情况下，我们证明系统的状态不再是之前认为的skyrmion量子比特，而是skyrmion量子多。我们构建了skyrmion量子多的密度矩阵并研究了其随时间的演化。获得的结果表明，所提出的模型可以进一步用于满足量子信息理论和量子skyrmionics的需求。我们表明，skyrmion量子多的$l_1$范数的相干性比skyrmion量子比特的相干性大一千倍。获得的结果为基于量子skyrmion的资源理论开辟了新的前景。 显示英文摘要

摘要： Since the pioneering work Lohani et. al., Phys. Rev. X 9, 041063 (2019), it became clear that quantum skyrmions have highly unusual properties as compared to the classical skyrmions and, due to their quantumness, cannot be described by continuous magnetic textures akin to the classical skyrmions. Competing nearest-neighbor and next-nearest-neighbor ferromagnetic and antiferromagnetic interactions in triangular spin-frustrated magnets lead to the formation of quantum skyrmion states. In frustrated magnets, skyrmions are characterized by the helical degree of freedom, which can store quantum information. In the limit of a weak electric field, the system can be described as a two-level system, i.e., a skyrmion qubit. Here, we propose a more general formulation of the problem and obtain general analytic solution of the model previously introduced in Psaroudaki et. al., Phys. Rev. Lett. 127, 067201 (2021). Our solution is valid not only for small barrier but for the arbitrary electric field. In the case of a significant barrier, we prove that the system's state is not a Skyrmion qubit as it was thought before, but a Skyrmion qudit. We constructed the density matrix of the Skyrmion qudit and studied its evolution in time. The obtained results suggest that the proposed model can be exploited further to meet the needs of quantum information theory and quantum skyrmionics. We showed that the $l_1$ norm of coherence of the skyrmion quantum qudit is a thousand times larger than the coherence of the skyrmion quantum qubit. The obtained result opens new perspectives for quantum skyrmion-based resource theory.