Josephson effect at the neutron-condensate interface

Establish the conditions under which the Josephson effect operates at the $^1S_0$--$^3P_2$ neutron-superfluid interface and quantify its contribution to late-time neutron-star heating relative to other dissipation channels.

Background

The proposed interface Josephson mechanism assumes a sufficiently sharp transition between singlet and triplet pairing and co-motion of proton flux tubes with neutron vortices. The review states that neither assumption has been justified from first principles.

References

Neither assumption has been rigorously justified from first principles. Establishing the conditions under which the Josephson effect operates, and quantifying its contribution to late-time neutron-star heating relative to other dissipation channels, are important open problems.

— Superfluidity and Vortex Dynamics in Neutron Stars  (2609.01022 - Link et al., 1 Sep 2026) in Section “Open questions and perspectives” under “Type-I superconductivity”