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arXiv · 1704.02395

Nambu identity and collective modes in superconductors and superfluid $^3$He

Gavriil Shchedrin·David M. Lee
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Abstract

Collective modes manifest themselves in a variety of different physical systems ranging from superconductors to superfluid $^{3}$He. The collective modes are generated via the Higgs-Anderson mechanism that is based on the symmetry breaking double well potential. Recently collective modes were explored in superconducting NbN and InO in the presence of a strong terahertz laser field. In both cases a single collective mode that oscillates with twice the frequency of the superconducting energy gap $Δ$ was discovered. Superfluid $^{3}$He is the host for a whole variety of collective modes. In particular, in the superfluid $^{3}$He B-phase, two massive collective modes were found with masses $\sqrt{{8}/{5}}Δ$ and $\sqrt{{12}/{5}}Δ$. We show that for both cases of the superconducting films and for the superfluid $^{3}$He B-phase, the collective modes satisfy the Nambu identity that relates the masses of different collective modes to the energy gap parameter $Δ$.

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Gavriil Shchedrin, David M. Lee. 2017-04-07. Nambu identity and collective modes in superconductors and superfluid $^3$He. https://doi.org/10.1088/0031-8949%2F91%2F1%2F013006

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