Optical spin transport theory of spin-1/2 topological Fermi superfluids

Abstract

We theoretically investigate optical (frequency-dependent) bulk spin transport properties in a spin-1/2 topological Fermi superfluid. We specifically consider a one-dimensional system with an interspin {\it p}-wave interaction, which can be realized in ultracold atom experiments. Developing the BCS-Leggett theory to describe the Bardeen-Cooper-Schrieffer (BCS) to Bose-Einstein condensate (BEC) evolution and the ${\mathbb{Z}}_2$ topological phase transition in this system, we show how the spin transport reflects these many-body aspects. We find that the optical spin conductivity, which is a small AC response of a spin current, shows the spin gapped spectrum in the wide parameter region and the gap closes at ${\mathbb{Z}}_2$ topological phase transition point. Moreover, the validity of the low-energy effective model of the Majorana zero mode is discussed along the BCS-BEC evolution in connection with the scale invariance at {\it p}-wave unitarity.

10 pages, 5 figures, accepted version for publication in Phys. Rev. B

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Cited by in corpus (6)

• Intersections of ultracold atomic polarons and nuclear clusters: How is a chart of nuclides modified in dilute neutron matter?
• Non-Hermitian topological Fermi superfluid near the $p$-wave unitary limit
• Stability against three-body clustering in one-dimensional spinless p-wave fermions
• Optical spin conductivity in ultracold quantum gases
• Spin conductivity spectrum and spin superfluidity in a binary Bose mixture
• Non-Hermitian $p$-wave superfluid and effects of the inelastic three-body loss in a one-dimensional spin-polarized Fermi gas