Axion mass estimates from resonant Josephson junctions
Axion mass estimates from resonant Josephson junctions
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DOI：
10.1016/j.dark.2015.03.002
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发表时间：
2015-03-01
影响因子：
5.5
通讯作者：
Beck, Christian
中科院分区：
文献类型：
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作者：
Beck, Christian
最近有人提出，来自银晕的暗物质轴子可以在约瑟夫森结中产生一个小的夏皮罗阶跃信号，其约瑟夫森频率与轴子质量共振(Beck，2013)。在这里，我们证明了在电压驱动的约瑟夫森结环境中的轴子场方程组允许一个非平凡解，其中轴子感应电流表现为振荡超电流。与这一非平凡解相关的位相线性变化意味着，在结弱链区的微小表面积上存在一个大磁场，它使入射的轴子衰变为微波光子。我们推导了约瑟夫森结实验的设计条件，使它们可以作为最佳的轴子探测器。在此背景下讨论了最近的四个独立实验。观测到的夏皮罗阶跃异常始终指向(110+/-2)µeV的轴子质量。这个质量值与最近的BICEP2结果是一致的，并暗示Peccei-Quinn对称性破缺发生在暴涨之后。(C)2015年提交人。爱思唯尔出版公司(Elsevier B.V.)
Recently it has been proposed that dark matter axions from the galactic halo can produce a small Shapiro step-like signal in Josephson junctions whose Josephson frequency resonates with the axion mass (Beck, 2013). Here we show that the axion field equations in a voltage-driven Josephson junction environment allow for a nontrivial solution where the axion-induced electrical current manifests itself as an oscillating supercurrent. The linear change of phase associated with this nontrivial solution implies the formal existence of a large magnetic field in a tiny surface area of the weak link region of the junction which makes incoming axions decay into microwave photons. We derive a condition for the design of Josephson junction experiments so that they can act as optimum axion detectors. Four independent recent experiments are discussed in this context. The observed Shapiro step anomalies of consistently point towards an axion mass of (110 +/- 2) mu eV. This mass value is compatible with the recent BICEP2 results and implies that Peccei-Quinn symmetry breaking was taking place after inflation. (C) 2015 The Author. Published by Elsevier B.V.