The Levitron(TM): An adiabatic trap for spins
The Levitron(TM): An adiabatic trap for spins
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DOI：
10.1098/rspa.1996.0062
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发表时间：
1996-05-08
影响因子：
3.5
通讯作者：
Berry, MV
中科院分区：
文献类型：
--
作者：
Berry, MV
陀螺形式的磁铁可以稳定地漂浮在排斥的磁性底座上方。稳定性的主要机制是保持势能 E 的静态平衡，该势能由自旋与基底磁场 B 的绝热耦合动态产生，并涉及该场的大小 B。 E 接近调和势，即拉普拉斯算子为零的势，恩肖定理将禁止稳定平衡。因此它的最小值很浅，需要巧妙地调整顶部的质量，使其悬挂在较小的高度范围内。通过由 B 的空间导数构建的有效“几何磁场”，顶部速度与 B 的后绝热动态耦合增加了稳定区间；陀螺旋转得越快，这种效应就越强。该装置类似于几个捕捉微观粒子的陷阱。
A magnet in the form of a spinning-top can float stably above a repelling magnetic base. The principal mechanism of stability is static equilibrium in a potential energy held E, arising dynamically from the adiabatic coupling of the spin with the magnetic field B of the base and involving the magnitude B of this field. E is close to a harmonic potential, that is, one whose Laplacian is zero, for which Earnshaw's theorem would forbid stable equilibrium. Therefore its minimum is very shallow, and requires the mass of the top to be adjusted delicately so that it hangs within a small interval of height. The stability interval is increased by a post-adiabatic dynamic coupling of the velocity of the top to B, through an effective 'geometric magnetic field' constructed from the spatial derivatives of B; this effect gets stronger as the top is spun faster. The device is analogous to several traps for microscopic particles.