Fistul M V, Wallraff A, Koval Y, Lukashenko A, Malomed B A, Ustinov A V
Physikalisches Institut III, Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany.
Phys Rev Lett. 2003 Dec 19;91(25):257004. doi: 10.1103/PhysRevLett.91.257004. Epub 2003 Dec 16.
The thermal and the quantum dissociation of a single vortex-antivortex (VAV) pair in an annular Josephson junction is experimentally observed and theoretically analyzed. In our experiments, the VAV pair is confined in a pinning potential controlled by external magnetic field and bias current. The dissociation of the pinned VAV pair manifests itself in a switching of the Josephson junction from the superconducting to the resistive state. The observed temperature and field dependence of the switching current distribution is in agreement with the analysis. The crossover from the thermal to the macroscopic quantum tunneling mechanism of dissociation occurs at a temperature of about 100 mK. We also predict the specific magnetic field dependence of the oscillatory energy levels of the pinned VAV state.
在环形约瑟夫森结中，单个涡旋 - 反涡旋（VAV）对的热解离和量子解离通过实验观测并进行了理论分析。在我们的实验中，VAV对被限制在由外部磁场和偏置电流控制的钉扎势中。被钉扎的VAV对的解离表现为约瑟夫森结从超导态到电阻态的转变。观测到的开关电流分布的温度和磁场依赖性与分析结果一致。解离机制从热机制到宏观量子隧穿机制的转变发生在约100 mK的温度下。我们还预测了被钉扎的VAV态的振荡能级的特定磁场依赖性。
