The influence of isotope substitution of neon atom on the integral cross sections of rotational excitation in NeNa2 collisionsZang, Hua-Ping; Li, Wen-Feng; Linghu, Rong-Feng; Cheng, Xin-Lu; Yang, Xiang-Dong
doi: 10.1088/1674-1056/20/2/020301pmid: N/A
This paper applies the multiple ellipsoid model to the 16Ne (20Ne, 28Ne, 34Ne)-Na2 collision systems, and calculates integral cross sections for rotational excitation at the incident energy of 190 meV. It can be seen that the accuracy of the integral cross sections can be improved by increasing the number of equipotential ellipsoid surfaces. Moreover, by analysing the differences of these integral cross sections, it obtains the change rules of the integral cross sections with the increase of rotational angular quantum number J, and with the change of the mass of isotope substitution neon atom. Finally, the contribution of different regions of the potential to inelastic cross sections for 20Ne-Na2 collision system is investigated at relative incident energy of 190 meV.
Reduced Dirac equation and Lamb shift as off-mass-shell effect in quantum electrodynamicsNi, Guang-Jiong; Xu, Jian-Jun; Lou, Sen-Yue
doi: 10.1088/1674-1056/20/2/020302pmid: N/A
Based on the accurate experimental data of energy-level differences in hydrogen-like atoms, especially the 1S2S transitions of hydrogen and deuterium, the necessity of introducing a reduced Dirac equation with reduced mass as the substitution of original electron mass is stressed. Based on new cognition about the essence of special relativity, we provide a reasonable argument for the reduced Dirac equation to have two symmetries, the invariance under the (newly defined) space-time inversion and that under the pure space inversion, in a noninertial frame. By using the reduced Dirac equation and within the framework of quantum electrodynamics in covariant form, the Lamb shift can be evaluated (at one-loop level) as the radiative correction on a bound electron staying in an off-mass-shell state-a new approach eliminating the infrared divergence. Hence the whole calculation, though with limited accuracy, is simplified, getting rid of all divergences and free of ambiguity.
Dark states and AharonovBohm oscillations in multi-quantum-dot systemsWang, Qiong; Liu, Jun; Tang, Ning; Zeng, Hao-Sheng
doi: 10.1088/1674-1056/20/2/020303pmid: N/A
We study the formation of dark states and the AharonovBohm effect in symmetrically/asymmetrically coupled three- and four-quantum-dot systems. It is found that without a transverse magnetic field, destructive interference can trap an electron in a dark state. However, the introduction of a transverse magnetic field can disrupt the dark state, giving rise to oscillation in current. For symmetrically structured quantum-dot systems, the oscillation has a period of one flux quanta. But for asymmetrically structured dot systems, the period of oscillation is halved. In addition, the dephasing due to charge noise also blocks the formation of dark states, while it does not change the period of oscillation.
Distributed quantum computation with superconducting qubit via LC circuit using dressed statesWu, Chao; Fang, Mao-Fa; Xiao, Xing; Li, Yan-Ling; Cao, Shuai
doi: 10.1088/1674-1056/20/2/020305pmid: N/A
A scheme is proposed where two superconducting qubits driven by a classical field interacting separately with two distant LC circuits connected by another LC circuit through mutual inductance, are used for implementing quantum gates. By using dressed states, quantum state transfer and quantum entangling gate can be implemented. With the help of the time-dependent electromagnetic field, any two dressed qubits can be selectively coupled to the data bus (the last LC circuit), then quantum state can be transferred from one dressed qubit to another and multi-mode entangled state can also be formed. As a result, the promising perspectives for quantum information processing of mesoscopic superconducting qubits are obtained and the distributed and scalable quantum computation can be implemented in this scheme.
Nonlinear electrodynamics coupled to teleparallel theory of gravityNashed, Gamal G. L.
doi: 10.1088/1674-1056/20/2/020402pmid: N/A
Using nonlinear electrodynamics coupled to teleparallel theory of gravity, regular charged spherically symmetric solutions are obtained. The nonlinear theory is reduced to the Maxwell one in the weak limit and the solutions correspond to charged spacetimes. One of the obtained solutions contains an arbitrary function which we call general solution since we can generate from it the other solutions. The metric associated with these spacetimes is the same, i.e., regular charged static spherically symmetric black hole. In calculating the energy content of the general solution using the gravitational energymomentum within the framework of the teleparallel geometry, we find that the resulting form depends on the arbitrary function. Using the regularized expression of the gravitational energymomentum we obtain the value of energy.