On Bosonic Magnetic Flux Operator and Bosonic Faraday Operator Formula

In the literature about mesoscopic Josephson devices the magnetic flux is considered as an operator, the fundamental commutative relation between the magnetic flux operator and the Cooper-pair charge operator is usually preengaged. In this paper we show that such a relation can be deduced from the basic Bose operators＇ commutative relation through the entangled state representation. The Faraday formula in bosonic form is then equivalent to the second Josephson equation. The current operator equation for LC mesoscopic circuit is also derived.     

Bosonic Operator Realization of Hamiltonian for a Superconducting Quantum Interference Device

Based on the appropriate bosonic phase operator diagonalized in the entangled state representation we construct the Hamiltonian operator model for a superconducting quantum interference device. The current operator and voltage operator equations are derived.     

Analogue Between Dynamic Hamiltonian-Operators of a Mesoscopic Ring Carrying Persistent Current and a Josephson Junction

By making the analogy between the operator Hamiltonians of a mesoscopic ring carrying the persistent current and a Josephson junction we have introduced a phase operator and entangled state representation to establish a theoretical formalism for the ring system.     

Analogue Between Dynamic Hamiltonian-Operators of a Mesoscopic Ring Carrying Persistent Current and a Josephson Junction

By making the analogy between the operator Hamiltonians of a mesoscopic ring carrying the persistent current and a Josephson junction we have introduced a phase operator and entangled state representation to establish a theoretical formalism for the ring system.     

Effects of Quantum Correction on Dynamical Phase Transition in a Single Species Bosonic Josephson Junction

In this paper,by employing Bogliubov backreaction method,we investigate quantum correction effects on dynamical phase transition in a single species bosonic Josephson junction induced by increasing nonlinear interaction.Compared with mean field theory results,we find that the transition point is shifted.The dynamical phase transition is accompanied by a change of the entanglement entropy,which is found to reach a maximum at the transition point of the mean field theory.     

Effects of Quantum Correction on Dynamical Phase Transition in a Single Species Bosonic Josephson Junction

In this paper, by employing Bogliubov backreaction method, we investigate quantum correction effects on dynamical phase transition in a single species bosonic Josephson junction induced by increasing nonlinear interaction. Compared with mean field theory results, we find that the transition point is shifted. The dynamical phase transition is accompanied by a change of the entanglement entropy, which is found to reach a maximum at the transition point of the mean field theory.     

On Harmonic Approximation for Large Josephson Junction Coupling Charge Qubits

We revisit the harmonic approximation (HA) for a large Josephson junction interacting with some charge qubits through the variational approach for the quantum dynamics of the junction-qubit coupling system. By making use of numerical calculation and analytical treatment, the conditions under which HA works well can be precisely presented to control the parameters implementing the two-qubit quantum logical gate through the couplings to the large junction with harmonic oscillator Hamiltonian.     

Characteristics of the Surface-Intrinsic Josephson Junction

During the fabrication of intrinsic Josephson junctions (IJJs) with Bi₂Sr₂CaCu₂O_8+δ (BSCCO) single crystals, the superconductivity of the surface Cu-O layer is degraded because of a deposited metal film on top of the stack. Thus, the characteristics of the surface junction consisting of the surface Cu-O double layers remarkably differ from those of the junctions deep in the stack, which will be referred to as ordinary IJJs. The electrical transport characteristics of the surface junction, such as I-V, I _c′-T, and R-T, show that the critical temperature T _c′ of the surface junction is always lower than that of ordinary IJJs, and that the change of its critical current I _c′ with temperature is different from that of ordinary IIJs. Furthermore, by shunting the surface junction resistively, we are able to observe the AC Josephson effect at 3-mm waveband. Translated from Chinese Journal of Low Temperature Physics, 2005, 27(2) (in Chinese)     

约瑟夫森结与阵列的非线性混沌行为及研究进展

约瑟夫森结是一种利用超导材料制备的新型量子电子器件,它的一个显著特性是具有高度的非线性,因而会出现明显的混沌行为。约瑟夫森结与阵列的混沌行为具有重要的研究和应用价值,受到了广泛的关注。文中对约瑟夫森结与阵列的非线性混沌行为及研究进展做一些介绍。     

On Mutual Transform Between Number-Difference State and Phase State Corresponding to Operational Phase Operator

In the mutual transform between the number-difference state and the phase state corresponding to the operational phase operator we find that there exists an end-point ambiguousness. This problem can be avoided by Lighthill＇s method.     

On Mutual Transform Between Number-Difference State and Phase State Corresponding to Operational Phase Operator

In the mutual transform between the number-difference state and the phase state corresponding to the operational phase operator we find that there exists an end-point ambiguousness. This problem can be avoided by Lighthill‘s method.     

Fluctuation power spectrum of a Josephson junction

The fluctuation power spectrum of the Josephson junction has been evaluated in the limit of large energy barriers [(U _n ^max−U _n ^min)γ]≫1 and small currents [x≪x _e]. The result is valid for finite capacitance of the junction. The effect of the fluctuating Josephson current on the voltageV(t) across the junction has also been taken into account.     

On the classical model for microwave induced escape from a Josephson washboard potential

We revisit the interpretation of earlier low temperature experiments on Josephson junctions under the influence of applied microwaves. It was claimed that these experiments unambiguously established a quantum phenomenology with discrete levels in shallow wells of the washboard potential, and macroscopic quantum tunneling. We here apply the previously developed classical theory to a direct comparison with the original experimental observations, and we show that the experimental data can be accurately represented classically. Thus, our analysis questions the necessity of the earlier quantum mechanical interpretation.     

电阻电容分路的约瑟夫森结中阵发性混沌及混沌控制的计算机模拟

通过计算机模拟研究了电阻电容分路的约瑟夫森结中的混沌行为,给出了结电压随阻尼参数及偏置直流电流变化的分岔图,从而展示了混沌产生的方式及混沌出现的参数区间,并基于弱周期扰动理论提出了控制RCSJJ中混沌的方案,模拟结果证明了该方案的有效性.     

Developing Josephson junction array chips for microvolt applications

Josephson junction array chips for microvolt applications have been designed and fabricated. A voltage step as small as 1 μV has been observed for a single junction in the array when it is driven by 483.59 MHz microwave. By selecting different parts of the array, it can output a voltage from 1 μV to 256 μV. The flat region of the voltage steps is over 200 μA.This kind of array is useful for potential microvolt applications.     

Anisotropy of p-wave Josephson junction

<正>The anisotropy of the dc Josephson current in the superconducting junctions of the p-wave equal spin pairing symmetry is theoretically investigated by the Furusaki-Tsukada-like formula.The current phase relations exhibit different oscillation periods and different phase shifts for the current along different directions,respectively.     

超导Josephson结直流I-V特性的数值计算

为了研究超导Josephson结的性质,选用四阶龙格-库塔法对RSJ模型下单个Josephson结及其阵列以及微波辐照下Josephson结的直流I-V特性进行了数值计算,并将模拟结果与实验结果进行了比较.     

Ac Josephson effect in Corbino-geometry Josephson junctions constructed on Bi2Te3 surface

Recently, a Corbino-geometry type of Josephson junction constructed on the surface of topological insulators has been proposed for hosting and braiding Majorana zero modes. As a first step to test this proposal, we successfully fabricated Corbino-geometry Josephson junctions (JJs) on the surface of Bi₂Te₃ flakes. Ac Josephson effect with fractional Shapiro steps was observed in the Corbino-geometry JJs while the flux in the junction area was quantized. By analyzing the experimental data using the resistively shunted Josephson junction model, we found that the Corbino-geometry JJs exhibit a skewed current—phase relation due to its high transparency. The results suggest that Corbino-geometry JJs constructed on the surface of topological insulators may provide a promising platform for studying Majorana-related physics.     

微波场中Josephson结的微波发射与吸收研究

采用数值仿真方法,研究微波场中约瑟夫森结微波感应台阶处的功率特性。发现微波场中约瑟夫森结不止吸收辐射,也发射辐射的情况。得到微波辐照和结电阻对功率吸收和发射的影响规律。结果表明,处于发射功率的状态对应的偏置电流范围占整个台阶总电流范围的比例可以趋于50%。这一发现对约瑟夫森结理论和应用研究具有重要的意义。     

Anomalous Transport Characteristics of High Temperature Superconductors and Josephson Currents

The transport characteristics of high temperature superconductor current and Josephson current is inves-tigated in the framework of the modified time-dependent Ginzburg-Landau model and the Lawrence-Doniach model.We evaluated the vortex equation and found that the signs of the high temperature superconductor current and theJosephson current can reverse. Some explicit expressions for different cases are derived, which accord with experimentaldata.