【摘要】 利用周期瞬子方法从理论上研究了环状偏流约瑟夫森结中的单个涡旋隧穿特性.将涡旋在约瑟夫森结中的运动简化为一个粒子在特定势阱中的运动,由于涡旋可以从阱中逃逸,这就使得涡旋在阱中的能态是不稳定的.理论上指出,正是由于涡旋的隧穿,使得涡旋所处的能态是亚稳态,该能态是一个复数,其虚部正比于能态的衰变率.通过理论计算得出:在温度较高的情况下,涡旋进行的是热隧穿,在低温条件下,涡旋的逃逸只能通过量子隧穿的方式.还指出过程中系统随着温度的降低,通过二阶转变过程从热隧穿过渡到了量子隧穿.更多还原

【Abstract】 The quantum tunneling of a vortex in an annular Josephson junction is investigated by using the periodic instanton method.In the model,a single vortex behavior in an annular junction subject to an in-plane field as a particle in a tilted washboard potential is simplified.The total decay rate is obtained which is valid for the entire range of temperature and show how it reduces to the appropriate results for the classical thermal activation at high temperatures,the thermally assisted tunneling at intermediate temperatures,and the pure quantum tunneling at low temperature.The exact definition of the "crossover" temperature can even be given and experimental data can be found to support our theoretical analysis.更多还原