论文标题
拓扑超流体$^3 $ He
Vortex-bound solitons in topological superfluid $^3$He
论文作者
论文摘要
$^3 $的不同超流体阶段由$ p $ - 波订单参数描述，其中包括轨道和旋转空间中的各向异性轴。各向异性轴表征了这些宏观连贯的量子多体系统中断裂的对称性。对于各向异性轴的某些方向，系统的自由能具有几个变性的最小值。结果，以不同能量最小值定居的两个此类区域之间的顺序参数的空间变化形成了拓扑孤子。这样的孤子可以终止在大块液体中，其中终端线形成涡流，并带有质量和自旋超流量电流的循环。 Here we discuss possible soliton-vortex structures based on the symmetry and topology arguments and focus on the three structures observed in experiments: solitons bounded by spin-mass vortices in the B phase, solitons bounded by half-quantum vortices in the polar and polar-distorted A phases, and the composite defect formed by a half-quantum vortex, soliton and the Kibble-Lazarides-Shafi wall in极延伸的B相。该观察结果基于核磁共振（NMR）技术，分为三种类型：首先，孤子可以在捕获的旋转波中形成一个潜在的孔，在移动频率下以NMR频谱中的额外峰观察到了潜在的孔；其次，它们可以提高NMR自旋进动的放松率。最后，孤子可以散装各向异性轴的边界条件，从而修改散装NMR信号。由于孤子的显着NMR签名以及使用外部磁场来操纵其结构的能力，Soliton已成为探测和控制Superfluid $^3 $ He的结构和动力学的重要工具，特别是半量子涡流的核心涡流。
The different superfluid phases of $^3$He are described by $p$-wave order parameters that include anisotropy axes both in the orbital and spin spaces. The anisotropy axes characterize the broken symmetries in these macroscopically coherent quantum many-body systems. The systems' free energy has several degenerate minima for certain orientations of the anisotropy axes. As a result, spatial variation of the order parameter between two such regions, settled in different energy minima, forms a topological soliton. Such solitons can terminate in the bulk liquid, where the termination line forms a vortex with trapped circulation of mass and spin superfluid currents. Here we discuss possible soliton-vortex structures based on the symmetry and topology arguments and focus on the three structures observed in experiments: solitons bounded by spin-mass vortices in the B phase, solitons bounded by half-quantum vortices in the polar and polar-distorted A phases, and the composite defect formed by a half-quantum vortex, soliton and the Kibble-Lazarides-Shafi wall in the polar-distorted B phase. The observations are based on nuclear magnetic resonance (NMR) techniques and are of three types: first, solitons can form a potential well for trapped spin waves, observed as an extra peak in the NMR spectrum at shifted frequency; second, they can increase the relaxation rate of the NMR spin precession; lastly, the soliton can present the boundary conditions for the anisotropy axes in bulk, modifying the bulk NMR signal. Owing to solitons' prominent NMR signatures and the ability to manipulate their structure with external magnetic field, solitons have become an important tool for probing and controlling the structure and dynamics of superfluid $^3$He, in particular half-quantum vortices with core-bound Majorana modes.
