Low Temperature Laboratory, School of Science, Aalto University, Finland.
Phys Rev Lett. 2012 Apr 6;108(14):145303. doi: 10.1103/PhysRevLett.108.145303. Epub 2012 Apr 3.
Long-lived coherent spin precession of (3)He-B at low temperatures around 0.2T(c) is a manifestation of Bose-Einstein condensation of spin-wave excitations or magnons in a magnetic trap which is formed by the order-parameter texture and can be manipulated experimentally. When the number of magnons increases, the orbital texture reorients under the influence of the spin-orbit interaction and the profile of the trap gradually changes from harmonic to a square well, with walls almost impenetrable to magnons. This is the first experimental example of Bose condensation in a box. By selective rf pumping the trap can be populated with a ground-state condensate or one at any of the excited energy levels. In the latter case the ground state is simultaneously populated by relaxation from the exited level, forming a system of two coexisting condensates.
在接近 0.2Tc 的低温下，（3）He-B 的长寿命相干自旋进动是磁场陷阱中自旋波激发或磁子玻色-爱因斯坦凝聚的一种表现，这种磁场陷阱由有序参数织构形成，并可以通过实验进行操控。当磁子数量增加时，轨道织构在自旋轨道相互作用的影响下重新取向，并且陷阱的轮廓逐渐从调和变化到方阱，阱壁对磁子几乎是不可穿透的。这是玻色-爱因斯坦凝聚在盒子中的第一个实验例子。通过选择性射频泵浦，陷阱可以填充基态凝聚体或任何激发能级上的凝聚体。在后一种情况下，基态同时通过从激发态的弛豫填充，形成两个共存凝聚体的系统。
