Plasma effects on Josephson phenomena in the Schwarzschild spacetime

Le résumé fourni par la source

We investigate an effective phenomenological scenario for gravitationally affected plasma modes in a localized superconducting junction in a static Schwarzschild spacetime. The analysis is formulated in the local inertial frame of a static observer, where the intrinsic Josephson effects are treated as unchanged to leading order, while the plasma modes are gravitationally dependent. To implement this framework, we assume that the electron subsystem behaves as a compressible degenerate Fermi gas in static equilibrium and follows a Tolman-type redshift relation for the chemical potential. This leads to an effective radial profile of the plasma frequency and, consequently, to a position-dependent proper collective-mode frequency. Within this framework, we derive an effective phase equation for the coupled Josephson–plasma dynamics and obtain the observable frequency measured by a distant observer as ω ∞ 2 ( r ) = α 2 ( r ) ω J 2 + α 1 / 2 ( r ) ω p , ∞ 2 , where α ( r ) = 1 − 2 G M / ( r c 2 ) is the Schwarzschild lapse function. The result reduces to the standard gravitational redshift in the Josephson-dominated regime, while in the plasma-dominated case it predicts a weaker suppression of the observed frequency. We further analyze the weak-field and near-horizon limits and present numerical illustrations of the modified scaling behavior. Our results may be interpreted as a proof-of-principle demonstration showing how a gravitationally sensitive plasma effect on the Josephson junction modifies the redshift of a collective superconducting mode, rather than as a universal prediction for an arbitrary rigid solid-state Josephson junction in curved spacetime.

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