Interaction of gravitational waves with superconductors

Abstract

Applying the Helmholtz Decomposition theorem to linearized General Relativity leads to a gauge‐invariant formulation where the transverse‐traceless part of the metric perturbation describes gravitational waves in matter. Gravitational waves incident on a superconductor can be described by a linear London‐like constituent equation characterized by a “gravitational shear modulus” and a corresponding plasma frequency and penetration depth. Electric‐like and magnetic‐like gravitational tensor fields are defined in terms of the strain field of a gravitational wave. It is shown that in the DC limit, the magnetic‐like tensor field is expelled from the superconductor in a gravitational Meissner‐like effect. The Cooper pair density is described by the Ginzburg‐Landau theory embedded in curved space‐time. The ionic lattice is modeled by quantum harmonic oscillators coupled to gravitational waves and characterized by quasi‐energy eigenvalues for the phonon modes. The formulation predicts the possibility of a dynamical Casimir effect since the zero‐point energy of the ionic lattice phonons is found to be modulated by the gravitational wave, in a quantum analog of a “Weber‐bar effect.” Applying periodic thermodynamics and the Debye model in the low‐temperature limit leads to a free energy density for the ionic lattice. Lastly, we relate the gravitational strain of space to the strain of matter to show that the response to a gravitational wave is far less for the Cooper pair density than for the ionic lattice. This predicts a charge separation effect in the superconductor as a result of the gravitational wave.