Possible resonance effect of axionic dark matter in Josephson junctions

Area of Science:

• Theoretical physics
• Astrophysics
• Condensed matter physics

Background:

• Axions are hypothetical elementary particles proposed as a dark matter candidate.
• Josephson junctions are sensitive superconducting devices exhibiting quantum mechanical phenomena.

Purpose of the Study:

• To propose a theoretical framework for detecting dark-matter axions using resonant S/N/S Josephson junctions.
• To interpret a previously observed resonance signal as evidence for axionic dark matter.

Main Methods:

• Developing theoretical arguments based on gauge-invariant axion Josephson phase angles.
• Analyzing the interaction process between galactic axions and Josephson junctions.
• Comparing theoretical predictions with experimental observations of resonance signals.

Main Results:

• Theoretical prediction of a Shapiro steplike feature in Josephson junctions due to axion interaction.
• Consistency of the theory with a previously observed resonance signal (Hoffmann et al., 2004).
• Estimation of axion mass (m(a)c²=0.11 meV) and galactic axionic dark matter density (0.05 GeV/cm³).

Conclusions:

• The observed resonance signal can be interpreted as a signature of dark-matter axions.
• Future experiments are needed to experimentally verify the dark-matter nature of this signal.
• This work provides a novel avenue for detecting axionic dark matter.