Ishizu, HiroshiYamamori, HirotakeArisawa, ShunichiTokiwa, Kazuyasu...
6页查看更多>>摘要：Applying a radian phase shift other than 2 pi is a key issue for superconducting circuits, such as flux qubits. Magnetic flux is useful when generating a phase shift. However, to apply a quantized magnetic flux to a phase shifter, a fine geometrical design is required. The magnetic flux generated by an external field generates noise. In this study, we propose a compact phase bias system that does not require an external field during operation. We confirm the phase shift of a direct current superconducting interference device (SQUID) placed on an ultrathin superconducting Nb bilayer with a through-hole by cooling it to a temperature below the superconducting transition temperature with an external field. Although the cause of the phase shift in our system is unclear, we believe that it may be caused by a fractional quantum in the bilayer. When the SQUID is replaced by a qubit, the phase shift can be applied to a phase bias.
原文链接:
NSTL
Elsevier
Hu, RuiZou, ChunlongDu, ShuangsongDing, Kaizhong...
6页查看更多>>摘要：Effective thermal conductivity (ETC) is an important parameter for thermal analysis of superconducting coils. In this paper, the analytical expression of the ETC of the adiabatic and closely compacted superconducting magnet is given, which provides a convenient and accurate method for calculating this parameter. Based on the thermal resistance model, a unit cell of coil is selected as the research object to educe the expression. The calculated results are in good agreement with the experimental data in the literature, which shows the rationality of the analytical expression. This paper further discuss about the effects of some factors on ETC. The results suggest that the thermal conductivity of insulation has a linear effect on the radial and axial ETC, while the specific residual resistivity ratio (RRR) of the copper matrix is positively correlated with the circumferential ETC. The circum-ferential ETC increases rapidly with the increase of the Cu-to-NbTi ratio (Cu/NbTi). However, when Cu / NbTi ratio is greater than 10, the increase of circumferential ETC is very small.
原文链接:- NSTL
- Elsevier
Kuznetsov, V., ITrofimov, O., V
7页查看更多>>摘要：We measured the critical temperatures and critical switching and retrapping currents of wide and narrow thinfilm quasi-one-dimensional superconducting aluminum structures of the same thickness in zero magnetic field. For the first time, we found that the narrower the structure, the lower the critical temperature and critical current density in the structure. Probably, the influence of depairing centers that are on dirty longitudinal boundaries of the structure, is the stronger than the narrower the structure. It is found for the first time that, in most cases, the temperature-dependent switching critical current in both structures is approximated by two functions. At temperatures below the temperature corresponding to the bottom of the resistive N-S transition of structures, the switching critical current is described by the Kupriyanov-Lukichev theory. At temperatures close to the top of the N-S transition, the switching current is linear with temperature and coincides with the critical Josephson current. At these temperatures, Josephson SNS junctions are formed in structures.
原文链接:- NSTL
- Elsevier
